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Caroline

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The Canadian Nature Photographer - What is an F-stop and why is it important in photography

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The most frequent question I get from new photographers is what is an F-stop? These numbers seem to confuse people and it's not surprising as the F-stop number gets bigger e.g. F11, F16, F22 - the diameter of the lens opening gets smaller.

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Patrick

http://www.stsite.com/camera/cam04.php

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different f-stops differentiate the hole of the lens that allows the light to come in

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different f-stops differentiate the hole of the lens that allows the light to come in

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Aung

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Patrick

http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

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Patrick

https://photographylife.com/what-is-aperture-in-photography

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Khoung Maw aung

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Caroline

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Depth of field refers to the range of distance that appears acceptably sharp. It varies depending on camera type, aperture and focusing distance, although print size and viewing distance can also influence our perception of depth of field. This tutorial is designed to give a better intuitive and technical understanding for photography, and provides a depth of field calculator to show how it varies with your camera settings.

The depth of field does not abruptly change from sharp to unsharp, but instead occurs as a gradual transition. In fact, everything immediately in front of or in back of the focusing distance begins to lose sharpness - even if this is not perceived by our eyes or by the resolution of the camera.

CIRCLE OF CONFUSION

Since there is no critical point of transition, a more rigorous term called the " circle of confusion" is used to define how much a point needs to be blurred in order to be perceived as unsharp. When the circle of confusion becomes perceptible to our eyes, this region is said to be outside the depth of field and thus no longer "acceptably sharp." The circle of confusion above has been exaggerated for clarity; in reality this would be only a tiny fraction of the camera sensor's area.

When does the circle of confusion become perceptible to our eyes? An acceptably sharp circle of confusion is loosely defined as one which would go unnoticed when enlarged to a standard 8x10 inch print, and observed from a standard viewing distance of about 1 foot.

At this viewing distance and print size, camera manufacturers assume a circle of confusion is negligible if no larger than 0.01 inches (when enlarged). As a result, camera manufacturers use the 0.01 inch standard when providing lens depth of field markers (shown below for f/22 on a 50mm lens). In reality, a person with 20/20 vision or better can distinguish features 1/3 this size, and so the circle of confusion has to be even smaller than this to achieve acceptable sharpness throughout.

A different maximum circle of confusion also applies for each print size and viewing distance combination. In the earlier example of blurred dots, the circle of confusion is actually smaller than the resolution of your screen for the two dots on either side of the focal point, and so these are considered within the depth of field. Alternatively, the depth of field can be based on when the circle of confusion becomes larger than the size of your digital camera's pixels.

Note that depth of field only sets a maximum value for the circle of confusion, and does not describe what happens to regions once they become out of focus. These regions are also called "bokeh," from Japanese (pronounced bo-ké). Two images with identical depth of field may have significantly different bokeh, as this depends on the shape of the lens diaphragm. In reality, the circle of confusion is usually not actually a circle, but is only approximated as such when it is very small. When it becomes large, most lenses will render it as a polygonal shape with 5-8 sides.

CONTROLLING DEPTH OF FIELD

Although print size and viewing distance influence how large the circle of confusion appears to our eyes, aperture and focusing distance are the two main factors that determine how big the circle of confusion will be on your camera's sensor. Larger apertures (smaller F-stop number) and closer focusing distances produce a shallower depth of field. The following test maintains the same focus distance, but changes the aperture setting:

note: images taken with a 200 mm lens (320 mm field of view on a 35 mm camera)

CLARIFICATION: FOCAL LENGTH AND DEPTH OF FIELD

Note that focal length has not been listed as influencing depth of field, contrary to popular belief. Even though telephoto lenses appear to create a much shallower depth of field, this is mainly because they are often used to magnify the subject when one is unable to get closer. If the subject occupies the same fraction of the image (constant magnification) for both a telephoto and a wide angle lens, the total depth of field is virtually* constant with focal length! This would of course require you to either get much closer with a wide angle lens or much farther with a telephoto lens, as demonstrated in the following chart:

Focal Length (mm)

Focus Distance (m)

Depth of Field (m)

Note: Depth of field calculations are at f/4.0 on a camera with a 1.6X crop factor,
using a circle of confusion of 0.0206 mm.

Note how there is indeed a subtle change for the smallest focal lengths. This is a real effect, but is negligible compared to both aperture and focusing distance. Even though the total depth of field is virtually constant, the fraction of the depth of field which is in front of and behind the focus distance does change with focal length, as demonstrated below:

This exposes a limitation of the traditional DoF concept: it only accounts for the total DoF and not its distribution around the focal plane, even though both may contribute to the perception of sharpness. Note how a wide angle lens provides a more gradually fading DoF behind the focal plane than in front, which is important for traditional landscape photographs.

Longer focal lengths may also appear to have a shallower depth of field because they enlarge the background relative to the foreground (due to their narrower angle of view). This can make an out of focus background look even more out of focus because its blur has become enlarged. However, this is another concept entirely, since depth of field only describes the sharp region of a photo - not the blurred regions.

On the other hand, when standing in the same place and focusing on a subject at the same distance, a longer focal length lens will have a shallower depth of field (even though the pictures will frame the subject entirely differently). This is more representative of everyday use, but is an effect due to higher magnification, not focal length.

Depth of field also appears shallower for SLR cameras than for compact digital cameras, because SLR cameras require a longer focal length to achieve the same field of view (see the tutorial on digital camera sensor sizes for more on this topic).

* Technical Note: We describe depth of field as being virtually constant because there are limiting cases where this does not hold true. For focal distances resulting in high magnification, or very near the hyperfocal distance, wide angle lenses may provide a greater DoF than telephoto lenses. On the other hand, at high magnification the traditional DoF calculation becomes inaccurate due to another factor: pupil magnification. This reduces the DoF advantage for most wide angle lenses, and increases it for telephoto and macro lenses. At the other limiting case, near the hyperfocal distance, the increase in DoF arises because the wide angle lens has a greater rear DoF, and can thus more easily attain critical sharpness at infinity.

CALCULATING DEPTH OF FIELD

In order to calculate the depth of field, one needs to first decide on an appropriate value for the maximum allowable circle of confusion. This is based on both the camera type (sensor or film size), and on the viewing distance / print size combination. Needless to say, knowing what this will be ahead of time often isn't straightforward. Try out the depth of field calculator tool to help you find this for your specific situation.

DEPTH OF FOCUS & APERTURE VISUALIZATION

Another implication of the circle of confusion is the concept of depth of focus (also called the "focus spread"). It differs from depth of field because it describes the distance over which light is focused at the camera's sensor, as opposed to the subject:

Diagram depicting depth of focus versus camera aperture. The purple lines comprising the edge of each shaded region represent the extreme angles at which light could potentially enter the aperture. The interior of the purple shaded regions represents all other possible angles.

The key concept is this: when an object is in focus, light rays originating from that point converge at a point on the camera's sensor. If the light rays hit the sensor at slightly different locations (arriving at a disc instead of a point), then this object will be rendered as out of focus - and increasingly so depending on how far apart the light rays are.

OTHER NOTES

Why not just use the smallest aperture (largest number) to achieve the best possible depth of field? Other than the fact that this may require prohibitively long shutter speeds without a camera tripod, too small of an aperture softens the image by creating a larger circle of confusion (or " Airy disk") due to an effect called diffraction - even within the plane of focus. Diffraction quickly becomes more of a limiting factor than depth of field as the aperture gets smaller. Despite their extreme depth of field, this is also why "pinhole cameras" have limited resolution.

For macro photography (high magnification), the depth of field is actually influenced by another factor: pupil magnification. This is equal to one for lenses which are internally symmetric, although for wide angle and telephoto lenses this is greater or less than one, respectively. A greater depth of field is achieved (than would be ordinarily calculated) for a pupil magnification less than one, whereas the pupil magnification does not change the calculation when it is equal to one. The problem is that the pupil magnification is usually not provided by lens manufacturers, and one can only roughly estimate it visually.

OTHER WEBSITES & FURTHER READING

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Understanding Depth of Field in Photography

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Depth of field refers to the range of distance that appears acceptably sharp. It varies depending on camera type, aperture and focusing distance, although print size and viewing distance can also influence our perception of depth of field.

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Caroline

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-Shwun

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Aperture is one of the three pillars of photography (the other two being Shutter Speed and ISO, which are two other chapters in our Photography Basics guide). Of the three, aperture is certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

What is Aperture?

Aperture can be defined as the opening in a lens through which light passes to enter the camera. It is an easy concept to understand if you just think about how your eyes work. As you move between bright and dark environments, the iris in your eyes either expands or shrinks, controlling the size of your pupil.

In photography, the "pupil" of your lens is called aperture. You can shrink or enlarge the size of the aperture to allow more or less light to reach your camera sensor. The image below shows an aperture in a lens:

Aperture can add dimension to your photos by controlling depth of field. At one extreme, aperture gives you a blurred background with a beautiful shallow focus effect. This is very popular for portrait photography.

At the other extreme, it will give you sharp photos from the nearby foreground to the distant horizon. Landscape photographers use this effect a lot.

On top of that, the aperture you choose also alters the exposure of your images by making them brighter or darker.

Aperture Explained in Video

If you prefer to understand how aperture works visually, we put together a video for you that goes through most of the basics. In the video, we go through what aperture is, how it works, and every effect that aperture has in photography. (These points are also covered further down in this article.)

How Aperture Affects Exposure

Aperture has several effects on your photographs. Perhaps the most obvious is the brightness, or exposure, of your images. As aperture changes in size, it alters the overall amount of light that reaches your camera sensor - and therefore the brightness of your image.

A large aperture (a wide opening) will pass a lot of light, resulting in a brighter photograph. A small aperture does just the opposite, making a photo darker. Take a look at the illustration below to see how it affects exposure:

In a dark environment - such as indoors or at night - you will probably want to select a large aperture to capture as much light as possible. This is the same reason why people's pupils dilate when it starts to get dark; pupils are the aperture of our eyes.

How Aperture Affects Depth of Field

The other critical effect of aperture is depth of field. Depth of field is the amount of your photograph that appears sharp from front to back. Some images have a "thin" or "shallow" depth of field, where the background is completely out of focus. Other images have a "large" or "high" depth of field, where both the foreground and background are sharp.

For example, here is an image with a shallow depth of field:

In the image above, you can see that the girl is in focus and appears sharp, while the background is completely out of focus. My choice of aperture played a big role here. I specifically used a large aperture in order to create a shallow focus effect (yes, the larger your aperture, the bigger this effect). This helped me bring the attention of the viewer to the subject, rather than busy background. Had I used a narrower aperture, the subject would not be separated from the background as effectively.

One trick to remember this relationship: a large aperture results in a large amount of both foreground and background blur. This is often desirable for portraits, or general photos of objects where you want to isolate the subject. Sometimes you can frame your subject with foreground objects, which will also look blurred relative to the subject, as shown in the example below:

Quick Note: The appearance of the out-of-focus areas (AKA whether it looks good or not) is often referred to as " bokeh". Bokeh is the property of the lens, and some lenses have better bokeh than others. This article explains how to get better bokeh as a photographer. Even though some lenses are better than others, almost all lenses are capable of a nice shallow focus effect if you use a large aperture and get close enough to your subject.

On the other hand, a small aperture results in a small amount of background blur, which is typically ideal for some types of photography such as landscape and architecture. In the landscape photo below, I used a small aperture to ensure that both my foreground and background were as sharp as possible from front to back:

Here is a quick comparison that shows the difference between using a large vs a small aperture and what it does to your depth of field:

As you can see, in the photograph on the left, only the head of the lizard appears in focus and sharp, while the background and foreground are both transitioning into blur. Meanwhile, the photo on the right has everything from front to back appearing in focus. This is what using large vs small aperture does to photographs.

What Are F-Stop and F-Number?

So far, we have only discussed aperture in general terms like large and small. However, it can also be expressed as a number known as "f-number" or " f-stop ", with the letter "f" appearing before the number, such as f/8.

Most likely, you have noticed aperture written this way on your camera before. On your LCD screen or viewfinder, your aperture will usually look something like this: f/2, f/3.5, f/8, and so on. Some cameras omit the slash and write f-stops like this: f2, f3.5, f8, and so on. For example, the Nikon camera below is set to an aperture of f/8:

So, f-stops are a way of describing the size of the aperture for a particular photo. If you want to find out more about this subject, we have a comprehensive article on f-stop that explains why it's written that way and is worth checking out.

Large vs Small Aperture

There's a catch - one important part of aperture that confuses beginning photographers more than anything else. This is something you really need to pay attention to and get correct: Small numbers represent large apertures, and large numbers represent small apertures!

That's not a typo. For example, f/2.8 is larger than f/4 and much larger than f/11. Most people find this awkward, since it goes against our basic intuition. Nevertheless, this is a fact of photography. Take a look at this chart:

This causes a huge amount of confusion among photographers, because it's completely the reverse of what you would expect at first. However, there is a reasonable and simple explanation that should make it much clearer to you: Aperture is a fraction.

When you are dealing with an f-stop of f/16, for example, you can think of it like the fraction 1/16th. Hopefully, you already know that a fraction like 1/16 is clearly much smaller than the fraction 1/4. For this exact reason, an aperture of f/16 is smaller than f/4. Looking at the front of your camera lens, this is what you'd see:

So, if photographers recommend a large aperture for a particular type of photography, they're telling you to use something like f/1.4, f/2, or f/2.8. And if they suggest a small aperture for one of your photos, they're recommending that you use something like f/8, f/11, or f/16.

How to Pick the Right Aperture

Now that you're familiar with large vs small apertures, how do you know what aperture to use for your photos? Let's revisit two of the most important effects of aperture: exposure and depth of field. First, here is a quick diagram to refresh your memory on how aperture affects the exposure of an image:

If you've read the prior chapter in our Photography Basics guide covering shutter speed, you already know that aperture isn't the only way to change how bright a photo is. Nevertheless, it plays an important role. In the graphic above, if I didn't allow myself to change any other camera settings like shutter speed or ISO, the optimal aperture would be f/5.6.

In a darker environment, where you aren't capturing enough light, the optimal aperture would change. For example, you may want to use a large aperture like f/2.8 at night, just like how our eye's pupils dilate to capture every last bit of light:

As for depth of field, recall that a large aperture value like f/2.8 will result in a large amount of background blur (ideal for shallow focus portraits), while values like f/8, f/11, or f/16 will give you a lot more depth of field (ideal for landscapes and architectural photography).

In fact, depth of field is the part of aperture that I recommend thinking about the most. My process for almost every photo I take goes like this:

Ask myself how much depth of field I want

Set an aperture that achieves it

Set a shutter speed that makes my photo the proper brightness

If that shutter speed leads to unsharp photos thanks to too much motion blur, dial back the shutter speed and raise my ISO instead

Win photo contest :)

Here is a quick chart that lays out everything we've covered so far:

Setting Aperture in Your Camera

If you haven't guessed it already, we highly recommend selecting your aperture manually as a photographer. If you allow the camera to set it automatically, you are likely to end up with the completely wrong depth of field in your image.

There are two modes in photography which allow you to select the aperture manually. These are aperture-priority mode and manual mode. Aperture-priority mode is written as "A" or "Av" on most cameras, while manual is written as "M." Usually, you can find these on the top dial of your camera (read more also in our article on camera modes):

In aperture-priority mode, you select the desired aperture, and the camera automatically selects your shutter speed. You can select ISO manually or automatically. Aperture priority mode is great for everyday photography, where you rarely need to worry about any camera settings other than aperture. It's what I use 95% of the time even for professional landscape and portrait photography.

In manual mode, you select both aperture and shutter speed manually. (ISO can again be manual or auto.) Manual mode takes more time and usually gives you the same results as aperture priority anyway. It's only needed in special situations where you need a consistent exposure from shot to shot, or when the camera's meter is messing up. I use it for Milky Way photography and for portraiture with flash.

Minimum and Maximum Aperture of Lenses

Every lens has a limit on how large or how small the aperture can get. If you take a look at the specifications of your lens, it should say what the maximum and minimum apertures are. For almost everyone, the maximum aperture will be more important, because it tells you how much light the lens can gather at its maximum (basically, how dark of an environment you can take photos - and how much of a shallow focus effect you can achieve).

A lens that has a maximum aperture of f/1.4 or f/1.8 is considered to be a "fast" lens, because it can pass through more light than, for example, a lens with a "slow" maximum aperture of f/4.0. That's why lenses with large apertures usually cost more.

By comparison, the minimum aperture is not that important, because almost all modern lenses can provide at least f/16 at the minimum. You will rarely need anything smaller than that for day-to-day photography.

With some zoom lenses, the maximum aperture will change as you zoom in and out. For example, with the Nikon 18-55mm f/3.5-5.6 AF-P lens, the largest aperture shifts gradually from f/3.5 at the wide end to just f/5.6 at the longer focal lengths. More expensive zooms tend to maintain a constant maximum aperture throughout their zoom range, like the Nikon 24-70mm f/2.8. Prime lenses also tend to have larger maximum apertures than zoom lenses, which is one of their major benefits.

The maximum aperture of a lens is so important that it's included in the name of the lens itself. Sometimes, it will be written with a colon rather than a slash, but it means the same thing (like the Nikon 50mm 1:1.4G below).

Examples of Which Aperture to Use

Now that we have gone through a thorough explanation of how aperture works and how it affects your images, let's take a look at the situations where you'd want to use various f-stops.

f/0.95 - f/1.4 - Such "fast" maximum apertures are only available on premium prime lenses, allowing them to gather as much light as possible. This makes them ideal for any kind of low-light photography (such as photographing the night sky, wedding receptions, portraits in dimly-lit rooms, corporate events, etc). With such wide f-stops, you will get very shallow depth of field at close distances, where the subject will appear separated from the background.

f/1.8 - f/2.0 - Some enthusiast-grade prime lenses are limited to f/1.8, which still has very good low-light capabilities. Also, if your purpose is to yield aesthetically-pleasing images with shallow focus, these lenses be of tremendous value. Shooting between f/1.8 and f/2 typically turns your backgrounds nice and creamy for portraiture and other similar types of photography.

f/2.8 - f/4 - Most zoom lenses are limited to a maximum aperture of f/2.8 to f/4 at best. While they are not as capable as f/1.4 lenses in terms of light-gathering capabilities, they are still enough to shoot in reasonably low light conditions, especially if the lens or camera has image stabilization. You'll get some subject separation at these apertures, but usually not enough to make the background completely fuzzy. Such apertures are great for travel, sports, and wildlife photography.

f/5.6 - f/8 - This is the right starting point for most landscape and architectural photography. It's also ideal for documentary and portrait photography where you don't want a blurry background. Also, most lenses are sharpest around f/5.6, which doesn't matter as much as getting the right depth of field, but is still nice.

f/11 - f/16 - Typically used for photographing scenes where as much depth of field as possible is needed, like macro photography or landscape photography with a nearby foreground. Even though these apertures offer more depth of field, they do lose some low-level sharpness due to the effect of lens diffraction.

f/22 and smaller - Only shoot at such small apertures if you know what you are doing. Sharpness suffers greatly at f/22 and smaller apertures because of diffraction, so you should avoid using them when possible. If you need to get more depth of field, it is usually best to move away from your subject or use a focus stacking technique instead.

You've made it this far, but are you willing to learn more about aperture? So far we have only touched the basics, but aperture does so much more to your photographs. Let's take a closer look.

Everything Aperture Does to Your Photos

Ever wondered how else aperture affects your photographs aside from brightness and depth of field? In this part of the article, we will go through all other ways aperture impacts your images, from sharpness to sunstars, and tell you exactly why each matters.

Before diving into too many specifics, here's a quick list of everything aperture affects in photography:

The brightness / exposure of your photos and depth of field, as discussed so far

Sharpness loss due to diffraction

Sharpness loss due to lens quality

Starburst effects on bright lights

Visibility of camera sensor dust specks

The quality of background highlights (bokeh)

Focus shift on some lenses

Ability to focus in low light (under some conditions)

Controlling the amount of light from the flash

1. The Negative Effect of Diffraction

So, if you're a landscape photographer who wants everything as sharp as possible, you should use your lens's smallest aperture, like f/22 or f/32 to get maximum depth of field, right?

No!

If we go back and take a close look at the photo of the lizard from earlier in this article, where I used apertures of f/4 and f/32, you can see how diffraction is making the second shot less sharp. Here are the images when zoomed in to 100% view:

Here, you're seeing an effect called diffraction. Physics majors will know what I'm talking about, but diffraction is a foreign concept to most people. So, what is it?

Diffraction is actually quite simple. When you use a tiny aperture like f/32, you literally squeeze the light that passes through your lens. It ends up interfering with itself, growing blurrier, and resulting in photos that are noticeably less sharp.

At what aperture does diffraction start to become an issue? It depends upon a number of factors, including the size of your camera sensor and the size of your final print. Personally, on my full-frame camera, I see hints of diffraction at f/8, but it's not enough to bother me. I actually use even smaller apertures like f/11 and f/16 all the time when I have a close foreground in landscape photography. However, I try to avoid f/22 or smaller, since I lose too much detail at that point.

Diffraction isn't necessarily a huge problem, but it exists. Don't be afraid to take pictures at f/11 or f/16 just because you lose a little bit of sharpness. In many cases, the added depth of field is worth the tradeoff.

In macro photography, diffraction can be a bit more of a problem close-focusing actually makes your effective aperture a lot smaller than it really is. Although the math behind that gets a bit complicated, basically, shooting at f/11 at macro distances will show diffraction a lot more compared to if you're shooting a landscape at f/11. In other words, keep an eye out for diffraction when shooting macro.

Side Note

If your camera has a smaller sensor or a very high pixel density, you'll see diffraction sooner. On APS-C sensors (like on Nikon D3x00 series, Nikon D5x00 series, Fuji X-series, Sony A6x00 series, and many others), divide all these numbers by 1.5. On Micro Four-Thirds cameras (like those from Olympus and Panasonic), divide all these numbers by 2. In other words, I don't recommend using f/11 with a micro four-thirds camera, since it's equivalent to f/22 with a full-frame camera.

2. Lens Aberrations

Here's a fun one. For some reason, everyone wants to take sharp photos! One of the ways to do so is to minimize the visibility of lens aberrations. So, what are lens aberrations? Quite simply, they are image quality problems with a photo, caused by your lens.

Although most problems in photography are because of user error - things like missed focus, poor exposure, or a distracting composition - lens aberrations are entirely due to your equipment. They are fundamental, optical problems that you'll notice with any lens if you look too closely, although some lenses are better than others. For example, consider the image below:

What's going on here? In this crop, most of the lights look smeared rather than perfectly round. On top of that, the crop just isn't very sharp. That's lens aberration at work! The lights didn't look this blurry in the real world. My lens added this problem.

It's likely that your lenses are blurrier at certain apertures than others, and it's almost always blurrier in the corner of the image than the center. That's due to lens aberrations.

Aberrations can appear in several different forms. This article would be way too long if I explained every possible aberration in detail: vignetting, spherical aberration, field curvature, coma, distortion, color fringing, and more. Instead, it's more important to know why aberrations occur, including how your aperture setting can reduce them.

It starts with a simple fact: designing lenses is difficult. When the manufacturer fixes one problem, another tends to appear. It's no surprise that modern lens designs are extremely complex.

Unfortunately, even today's lenses aren't perfect. They tend to work fine in the center of an image, but everything gets worse near the edges. That's because lenses are especially difficult to design around the corners.

Here's a diagram that explains what I mean:

And that brings us to aperture.

Many people don't realize a simple fact about aperture: it literally blocks the light transmitted by the edges of your lens. (This doesn't lead to black corners in your photos, because the center regions of a lens can still transmit light to the edges of your camera sensor.)

As your aperture closes, more and more light from the sides of your lens will be blocked, never making it to your camera sensor. Only the light from the center area will pass through and form your photo! As the diagram above shows, this central area is far easier for camera manufacturers to design. The end result is that your photos will have fewer aberrations at smaller and smaller apertures.

How does this look in practice? See the photos below (heavy crops from the top-left corner):

What you're seeing above may look like an increase in sharpness, but it's really a decrease in aberrations. The end result? At f/5.6 on this particular lens, my photo is much sharper than at f/1.4.

Here's a key question: How does this balance out with diffraction, which harms sharpness increasingly more as your aperture gets narrower and narrower?

In practice, the answer is that most lenses end up sharpest around f/4, f/5.6, or f/8. Those "medium" apertures are small enough to block light from the edges of a lens, but they aren't so small that diffraction is a significant problem. However, you'll want to test this on your own equipment.

Of course, you can still take good photos at large apertures like f/1.4 or f/2. As I mentioned earlier, portrait photographers sometimes pay thousands of dollars to get a lens exactly for that purpose! So, don't lock your lens to f/5.6 just because it gives you a tad more corner sharpness up close. It's better to choose an aperture that gives you the right artistic look to the image.

Side Note

Some types of aberrations don't change much as you stop down, or they may even get slightly worse. Axial chromatic aberration, for example - color fringes near the edges of your frame - often work that way. This is normal. It happens because a small aperture doesn't inherently reduce aberrations; it simply blocks light that has passed through the edges of your lens. So, naturally, if the edges aren't the source of your problem, you won't see an improvement by stopping down.

3. Starburst and Sunstar Effects

Starbursts, also called sunstars, are beautiful elements that you'll find in certain photographs. Despite the odd names - one a type of candy; the other a type of starfish - I always try to capture them in my landscape photos. Here's an example:

How does this work? Essentially, for every aperture blade in your lens, you'll end up with a sunbeam. This only happens if you photograph a small, bright point of light, such as the sun when it is partly blocked. This is fairly common in landscape photography. If you want the strongest possible starburst, use a small aperture. Whenever the sun is in my photo, I almost always set f/16 purely to capture this effect.

Also, the starburst effect looks different from lens to lens. It all depends upon your aperture blades. If your lens has six aperture blades, you'll get six sunbeams. If your lens has eight aperture blades, you'll get eight sunbeams. And, if your lens has nine aperture blades, you'll get eighteen sunbeams.

Wait, what?

That's no typo. You always end up with an even number of sunbeams. If your lens has an odd number of aperture blades, you'll get double the number of sunbeams.

It sounds strange, but the reason is actually quite simple. In lenses with an even number of aperture blades (and a fully symmetrical design), half of the sunbeams will overlap the other half. So, you don't see all of them in your final photo.

Here's a diagram to show what I mean:

Most Nikon lenses have seven or nine aperture blades, resulting in 14 and 18 sunbeams respectively. Most Canon lenses have eight aperture blades, resulting in eight sunbeams. I took the photo above using the Nikon 20mm f/1.8G lens, which has 7 aperture blades. That's why the image has 14 sunbeams.

It's not just the number of blades that matters, though - their shape is also important. Some aperture blades are rounded (which results in a more pleasant out-of-focus background blur), and others are straight. If your goal is to capture good starbursts, straight aperture blades typically produce more defined rays of light.

Again, some lenses are better than others in this regard. For the best results, find a lens that's known to have good starbursts, and then set it to a small aperture like f/16. That's going to give you the strongest definition in your starbursts.

Finally, there's one last related effect that I wanted to mention briefly. When you shoot into the sun, you might end up with flare in your photographs, as shown below. Depending upon your chosen aperture, the size and shape of this lens flare may change slightly. This isn't a big deal, but it still exists.

4. Small Aperture and Unwanted Elements

When you shoot through things such as fences, dirty windows, plants, and even water droplets on your lens, you'll probably be disappointed by photos taken with a small aperture.

Small apertures like f/11 and f/16 give you such a large depth of field that you may accidentally include elements that you don't want to be in focus! For example, if you're shooting at a waterfall or by the ocean, an aperture of f/16 could render a tiny water droplet on your lens into a distinct, ugly blob:

In cases like that, it's better just to use a wider aperture - something like f/5.6, perhaps - in order to capture the water droplet so out-of-focus that it doesn't even appear in your image. In this particular case, you could simply wipe the droplet off, but that's not possible if you're shooting through something like a dirty window.

Side Note

You might have realized that this section is really just an extension of depth of field, and that's true! However, it's a bit of a special case, so I decided to mention it specifically.

Another example of shooting through things is when a piece of dust lands on your camera sensor. Unfortunately, as you change lenses, this is very common. Dust specks on your camera sensor will show up very clearly at small apertures like f/16, even if they're invisible at something larger, like f/4.

Luckily, they are very easy to remove in post-production software like Photoshop or Lightroom, though it can be annoying if you have to remove dozens of them from a single photo. That's why you should always keep your camera sensor clean.

5. Changes to Your Bokeh

What is bokeh? It's simply the quality of your background blur. If you take a lot of portraits, macro photos, or wildlife photos, you'll end up with out-of-focus backgrounds in most of your images. Naturally, you want them to look as good as possible! Different aperture settings will change the shape of your background blur.

Why is that? It's because the background blur of your photographs always takes on the shape of your aperture blades. So, if your aperture blades are shaped like a heart, you'll end up with heart-shaped background blur. Most of the time, that would qualify as distracting bokeh, although it's kind of cute in this photo of two fake tortoises:

On some lenses, aperture blades change shape a bit as they open and close. Large aperture settings (such as f/1.8) often have rounder background blur compared to smaller aperture settings. You'll also get more background blur at large apertures, since your depth of field is thinner.

If bokeh is something that matters to you, you'll want to test this on your particular lenses. Take some out-of-focus photos of a busy scene, each using a different aperture setting, and see which one looks the best. Most of the time, it will be the lens's widest aperture, but not always.

6. Focus Shift Issues

With certain lenses - even if you're in manual focus, and you don't move your focus ring - your point of focus may shift as you use smaller and smaller apertures.

Obviously, this isn't ideal. How do you tell if your lens has problematic focus shift? It's pretty easy. Here are the steps:

Put your camera on a tripod, and set your lens to manual focus.

Find an object with small details that extends backwards, and focus at the center of it. A table with a tablecloth works well.

Double check: When take a test photo and magnify it, you should see pixel-level details, as well as portions of the photo that are clearly out of focus.

Take a photo at your lens's widest aperture, and then at progressively smaller apertures. Be sure not to move your focus ring, and double check that you are using manual focus.

On your computer, zoom into 100% on these photos and see if the sharpest point of focus moves continuously farther back as you stop down. The more it moves, the worse your focus shift issue is.

You're done!

If your lens has extreme levels of focus shift, you'll want to compensate for it:

With your widest aperture, just focus like normal.

As you stop down the aperture, make sure to set your aperture first, then focus second (rather than focusing first). On DSLRs, we recommend focusing in live view at these apertures, because the viewfinder always focuses at the widest aperture. Mirrorless camera users don't need to worry about that.

With small apertures like f/8 and beyond, your depth of field will be large enough to hide any focus shift problems, so just focus like normal.

Side Note

When it comes down to it, focus shift is just another type of lens aberration. The edges of your lens may not focus light the same as the center, so, by stopping down - again, blocking light from the edges - your focus point changes slightly. That's the underlying reason for this effect.

7. Ease of Focusing

The autofocus system on your camera doesn't work well unless it receives plenty of light.

So, if you're shooting with a cheaper lens like a 70-300mm f/4.5-5.6, the largest aperture isn't bright enough to gather a lot of light. Focusing in dark conditions may be impacted. This is part of why a lot of pro photographers will use a more expensive lens like a 70-200mm f/2.8 instead.

You'll also enjoy a brighter viewfinder (on a DSLR) or a less noisy viewfinder (on a mirrorless camera) if your lens has a large maximum aperture. If you shoot a lot in low light, this can make it much easier to focus and compose your images.

8. Flash Exposure

When using speedlights or any kind of strobes, it is important to remember that aperture takes on a whole different role of controlling flash exposure. While shutter speed's role becomes controlling ambient light, aperture has an outsized impact on how much light from your flash is captured. Even though it's just a subset of exposure, we wanted to include it in this section, since flash is tightly correlated to lens aperture.

A Chart of Everything Aperture Does

Once you understand the information above, you will know everything aperture does to your photos. However, it may take a few re-reads of this article before it's all completely clear.

Practice is your best friend. Go outside, take some photos, and get a feel for aperture yourself.

If it helps, I compiled the main information in this article into a chart. This chart covers the most important effects of aperture in photography, as well as common terms that photographers use to describe their settings.

Note that to make this diagram easier to see, I did not darken or lighten any of the sample illustrations (as would occur in the real world). Instead, I simply wrote "brightest" through "darkest":

Although this chart is intentionally simplified, it covers all the basics that you need to know. Feel free to download and print this chart if you find it useful. Just right-click on the image, then select "save as," and pick the location where you want to store it.

Aperture FAQ

We put together some of the most frequently-asked questions related to aperture below.
How Does Aperture Affect Bokeh?
Bokeh refers to the quality of out-of-focus highlights of the image rendered by the camera lens. Using the maximum aperture of the lens will typically yield circular background highlights of large size, whereas stopping down the lens will typically result in highlights looking smaller and taking different shapes such as heptagon. These shapes depend on the number of aperture blades and their roundness. Here is an image of a 50mm f/1.4 prime lens stopped down to f/2.8 and f/4 apertures:

How Does Aperture Affect Sharpness?
Aperture is clearly a crucial setting in photography and it is possibly the single most important setting of all. Aperture affects several different parts of your photo, but you'll get the hang of everything fairly quickly. For a quick summary, a narrow aperture...

Makes your photos darker

Gives you more depth of field

Increases blur from diffraction

Decreases blur from most lens aberrations

Makes sensor dust more visible

Heightens the intensity of starbursts

...whereas a wide aperture does the opposite.

Soon, this won't be something that you even need to think about; you'll remember it all naturally. Personally, if I want a starburst effect in my photos, I immediately know to use an aperture of f/16. When I need as much light as possible, I set a larger aperture like f/2.8 or f/2 without a second thought. It doesn't take too much practice to get to that point.

With how important aperture is, it shouldn't be a surprise that, at Photography Life, we shoot in aperture-priority or manual mode all of the time. We simply never want the camera to select the aperture for us. It's just too important, and it is one of those basic settings that every beginner or advanced photographer needs to know in order to take the best possible images.

As always, it's best if you learn all this for yourself. Find something spectacular to capture, and put your new knowledge into practice. The more photos you take, the more you'll learn. Aperture is no exception.

Below are some other related posts you might enjoy:

Hopefully, you found that this article explains the basics of aperture in a way that is understandable and straightforward.

If you are ready to move on, the next important camera setting to learn is ISO, which we explain in Chapter 5 of our Photography Basics guide.

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What is Aperture? Understanding Aperture in Photography

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Aperture is one of the three pillars of photography, and certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

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Aperture is one of the three pillars of photography (the other two being Shutter Speed and ISO, which are two other chapters in our Photography Basics guide). Of the three, aperture is certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

What is Aperture?

Aperture can be defined as the opening in a lens through which light passes to enter the camera. It is an easy concept to understand if you just think about how your eyes work. As you move between bright and dark environments, the iris in your eyes either expands or shrinks, controlling the size of your pupil.

In photography, the "pupil" of your lens is called aperture. You can shrink or enlarge the size of the aperture to allow more or less light to reach your camera sensor. The image below shows an aperture in a lens:

Aperture can add dimension to your photos by controlling depth of field. At one extreme, aperture gives you a blurred background with a beautiful shallow focus effect. This is very popular for portrait photography.

At the other extreme, it will give you sharp photos from the nearby foreground to the distant horizon. Landscape photographers use this effect a lot.

On top of that, the aperture you choose also alters the exposure of your images by making them brighter or darker.

Aperture Explained in Video

If you prefer to understand how aperture works visually, we put together a video for you that goes through most of the basics. In the video, we go through what aperture is, how it works, and every effect that aperture has in photography. (These points are also covered further down in this article.)

How Aperture Affects Exposure

Aperture has several effects on your photographs. Perhaps the most obvious is the brightness, or exposure, of your images. As aperture changes in size, it alters the overall amount of light that reaches your camera sensor - and therefore the brightness of your image.

A large aperture (a wide opening) will pass a lot of light, resulting in a brighter photograph. A small aperture does just the opposite, making a photo darker. Take a look at the illustration below to see how it affects exposure:

In a dark environment - such as indoors or at night - you will probably want to select a large aperture to capture as much light as possible. This is the same reason why people's pupils dilate when it starts to get dark; pupils are the aperture of our eyes.

How Aperture Affects Depth of Field

The other critical effect of aperture is depth of field. Depth of field is the amount of your photograph that appears sharp from front to back. Some images have a "thin" or "shallow" depth of field, where the background is completely out of focus. Other images have a "large" or "high" depth of field, where both the foreground and background are sharp.

For example, here is an image with a shallow depth of field:

In the image above, you can see that the girl is in focus and appears sharp, while the background is completely out of focus. My choice of aperture played a big role here. I specifically used a large aperture in order to create a shallow focus effect (yes, the larger your aperture, the bigger this effect). This helped me bring the attention of the viewer to the subject, rather than busy background. Had I used a narrower aperture, the subject would not be separated from the background as effectively.

One trick to remember this relationship: a large aperture results in a large amount of both foreground and background blur. This is often desirable for portraits, or general photos of objects where you want to isolate the subject. Sometimes you can frame your subject with foreground objects, which will also look blurred relative to the subject, as shown in the example below:

Quick Note: The appearance of the out-of-focus areas (AKA whether it looks good or not) is often referred to as " bokeh". Bokeh is the property of the lens, and some lenses have better bokeh than others. This article explains how to get better bokeh as a photographer. Even though some lenses are better than others, almost all lenses are capable of a nice shallow focus effect if you use a large aperture and get close enough to your subject.

On the other hand, a small aperture results in a small amount of background blur, which is typically ideal for some types of photography such as landscape and architecture. In the landscape photo below, I used a small aperture to ensure that both my foreground and background were as sharp as possible from front to back:

Here is a quick comparison that shows the difference between using a large vs a small aperture and what it does to your depth of field:

As you can see, in the photograph on the left, only the head of the lizard appears in focus and sharp, while the background and foreground are both transitioning into blur. Meanwhile, the photo on the right has everything from front to back appearing in focus. This is what using large vs small aperture does to photographs.

What Are F-Stop and F-Number?

So far, we have only discussed aperture in general terms like large and small. However, it can also be expressed as a number known as "f-number" or " f-stop ", with the letter "f" appearing before the number, such as f/8.

Most likely, you have noticed aperture written this way on your camera before. On your LCD screen or viewfinder, your aperture will usually look something like this: f/2, f/3.5, f/8, and so on. Some cameras omit the slash and write f-stops like this: f2, f3.5, f8, and so on. For example, the Nikon camera below is set to an aperture of f/8:

So, f-stops are a way of describing the size of the aperture for a particular photo. If you want to find out more about this subject, we have a comprehensive article on f-stop that explains why it's written that way and is worth checking out.

Large vs Small Aperture

There's a catch - one important part of aperture that confuses beginning photographers more than anything else. This is something you really need to pay attention to and get correct: Small numbers represent large apertures, and large numbers represent small apertures!

That's not a typo. For example, f/2.8 is larger than f/4 and much larger than f/11. Most people find this awkward, since it goes against our basic intuition. Nevertheless, this is a fact of photography. Take a look at this chart:

This causes a huge amount of confusion among photographers, because it's completely the reverse of what you would expect at first. However, there is a reasonable and simple explanation that should make it much clearer to you: Aperture is a fraction.

When you are dealing with an f-stop of f/16, for example, you can think of it like the fraction 1/16th. Hopefully, you already know that a fraction like 1/16 is clearly much smaller than the fraction 1/4. For this exact reason, an aperture of f/16 is smaller than f/4. Looking at the front of your camera lens, this is what you'd see:

So, if photographers recommend a large aperture for a particular type of photography, they're telling you to use something like f/1.4, f/2, or f/2.8. And if they suggest a small aperture for one of your photos, they're recommending that you use something like f/8, f/11, or f/16.

How to Pick the Right Aperture

Now that you're familiar with large vs small apertures, how do you know what aperture to use for your photos? Let's revisit two of the most important effects of aperture: exposure and depth of field. First, here is a quick diagram to refresh your memory on how aperture affects the exposure of an image:

If you've read the prior chapter in our Photography Basics guide covering shutter speed, you already know that aperture isn't the only way to change how bright a photo is. Nevertheless, it plays an important role. In the graphic above, if I didn't allow myself to change any other camera settings like shutter speed or ISO, the optimal aperture would be f/5.6.

In a darker environment, where you aren't capturing enough light, the optimal aperture would change. For example, you may want to use a large aperture like f/2.8 at night, just like how our eye's pupils dilate to capture every last bit of light:

As for depth of field, recall that a large aperture value like f/2.8 will result in a large amount of background blur (ideal for shallow focus portraits), while values like f/8, f/11, or f/16 will give you a lot more depth of field (ideal for landscapes and architectural photography).

In fact, depth of field is the part of aperture that I recommend thinking about the most. My process for almost every photo I take goes like this:

Ask myself how much depth of field I want

Set an aperture that achieves it

Set a shutter speed that makes my photo the proper brightness

If that shutter speed leads to unsharp photos thanks to too much motion blur, dial back the shutter speed and raise my ISO instead

Win photo contest :)

Here is a quick chart that lays out everything we've covered so far:

Setting Aperture in Your Camera

If you haven't guessed it already, we highly recommend selecting your aperture manually as a photographer. If you allow the camera to set it automatically, you are likely to end up with the completely wrong depth of field in your image.

There are two modes in photography which allow you to select the aperture manually. These are aperture-priority mode and manual mode. Aperture-priority mode is written as "A" or "Av" on most cameras, while manual is written as "M." Usually, you can find these on the top dial of your camera (read more also in our article on camera modes):

In aperture-priority mode, you select the desired aperture, and the camera automatically selects your shutter speed. You can select ISO manually or automatically. Aperture priority mode is great for everyday photography, where you rarely need to worry about any camera settings other than aperture. It's what I use 95% of the time even for professional landscape and portrait photography.

In manual mode, you select both aperture and shutter speed manually. (ISO can again be manual or auto.) Manual mode takes more time and usually gives you the same results as aperture priority anyway. It's only needed in special situations where you need a consistent exposure from shot to shot, or when the camera's meter is messing up. I use it for Milky Way photography and for portraiture with flash.

Minimum and Maximum Aperture of Lenses

Every lens has a limit on how large or how small the aperture can get. If you take a look at the specifications of your lens, it should say what the maximum and minimum apertures are. For almost everyone, the maximum aperture will be more important, because it tells you how much light the lens can gather at its maximum (basically, how dark of an environment you can take photos - and how much of a shallow focus effect you can achieve).

A lens that has a maximum aperture of f/1.4 or f/1.8 is considered to be a "fast" lens, because it can pass through more light than, for example, a lens with a "slow" maximum aperture of f/4.0. That's why lenses with large apertures usually cost more.

By comparison, the minimum aperture is not that important, because almost all modern lenses can provide at least f/16 at the minimum. You will rarely need anything smaller than that for day-to-day photography.

With some zoom lenses, the maximum aperture will change as you zoom in and out. For example, with the Nikon 18-55mm f/3.5-5.6 AF-P lens, the largest aperture shifts gradually from f/3.5 at the wide end to just f/5.6 at the longer focal lengths. More expensive zooms tend to maintain a constant maximum aperture throughout their zoom range, like the Nikon 24-70mm f/2.8. Prime lenses also tend to have larger maximum apertures than zoom lenses, which is one of their major benefits.

The maximum aperture of a lens is so important that it's included in the name of the lens itself. Sometimes, it will be written with a colon rather than a slash, but it means the same thing (like the Nikon 50mm 1:1.4G below).

Examples of Which Aperture to Use

Now that we have gone through a thorough explanation of how aperture works and how it affects your images, let's take a look at the situations where you'd want to use various f-stops.

f/0.95 - f/1.4 - Such "fast" maximum apertures are only available on premium prime lenses, allowing them to gather as much light as possible. This makes them ideal for any kind of low-light photography (such as photographing the night sky, wedding receptions, portraits in dimly-lit rooms, corporate events, etc). With such wide f-stops, you will get very shallow depth of field at close distances, where the subject will appear separated from the background.

f/1.8 - f/2.0 - Some enthusiast-grade prime lenses are limited to f/1.8, which still has very good low-light capabilities. Also, if your purpose is to yield aesthetically-pleasing images with shallow focus, these lenses be of tremendous value. Shooting between f/1.8 and f/2 typically turns your backgrounds nice and creamy for portraiture and other similar types of photography.

f/2.8 - f/4 - Most zoom lenses are limited to a maximum aperture of f/2.8 to f/4 at best. While they are not as capable as f/1.4 lenses in terms of light-gathering capabilities, they are still enough to shoot in reasonably low light conditions, especially if the lens or camera has image stabilization. You'll get some subject separation at these apertures, but usually not enough to make the background completely fuzzy. Such apertures are great for travel, sports, and wildlife photography.

f/5.6 - f/8 - This is the right starting point for most landscape and architectural photography. It's also ideal for documentary and portrait photography where you don't want a blurry background. Also, most lenses are sharpest around f/5.6, which doesn't matter as much as getting the right depth of field, but is still nice.

f/11 - f/16 - Typically used for photographing scenes where as much depth of field as possible is needed, like macro photography or landscape photography with a nearby foreground. Even though these apertures offer more depth of field, they do lose some low-level sharpness due to the effect of lens diffraction.

f/22 and smaller - Only shoot at such small apertures if you know what you are doing. Sharpness suffers greatly at f/22 and smaller apertures because of diffraction, so you should avoid using them when possible. If you need to get more depth of field, it is usually best to move away from your subject or use a focus stacking technique instead.

You've made it this far, but are you willing to learn more about aperture? So far we have only touched the basics, but aperture does so much more to your photographs. Let's take a closer look.

Everything Aperture Does to Your Photos

Ever wondered how else aperture affects your photographs aside from brightness and depth of field? In this part of the article, we will go through all other ways aperture impacts your images, from sharpness to sunstars, and tell you exactly why each matters.

Before diving into too many specifics, here's a quick list of everything aperture affects in photography:

The brightness / exposure of your photos and depth of field, as discussed so far

Sharpness loss due to diffraction

Sharpness loss due to lens quality

Starburst effects on bright lights

Visibility of camera sensor dust specks

The quality of background highlights (bokeh)

Focus shift on some lenses

Ability to focus in low light (under some conditions)

Controlling the amount of light from the flash

1. The Negative Effect of Diffraction

So, if you're a landscape photographer who wants everything as sharp as possible, you should use your lens's smallest aperture, like f/22 or f/32 to get maximum depth of field, right?

No!

If we go back and take a close look at the photo of the lizard from earlier in this article, where I used apertures of f/4 and f/32, you can see how diffraction is making the second shot less sharp. Here are the images when zoomed in to 100% view:

Here, you're seeing an effect called diffraction. Physics majors will know what I'm talking about, but diffraction is a foreign concept to most people. So, what is it?

Diffraction is actually quite simple. When you use a tiny aperture like f/32, you literally squeeze the light that passes through your lens. It ends up interfering with itself, growing blurrier, and resulting in photos that are noticeably less sharp.

At what aperture does diffraction start to become an issue? It depends upon a number of factors, including the size of your camera sensor and the size of your final print. Personally, on my full-frame camera, I see hints of diffraction at f/8, but it's not enough to bother me. I actually use even smaller apertures like f/11 and f/16 all the time when I have a close foreground in landscape photography. However, I try to avoid f/22 or smaller, since I lose too much detail at that point.

Diffraction isn't necessarily a huge problem, but it exists. Don't be afraid to take pictures at f/11 or f/16 just because you lose a little bit of sharpness. In many cases, the added depth of field is worth the tradeoff.

In macro photography, diffraction can be a bit more of a problem close-focusing actually makes your effective aperture a lot smaller than it really is. Although the math behind that gets a bit complicated, basically, shooting at f/11 at macro distances will show diffraction a lot more compared to if you're shooting a landscape at f/11. In other words, keep an eye out for diffraction when shooting macro.

Side Note

If your camera has a smaller sensor or a very high pixel density, you'll see diffraction sooner. On APS-C sensors (like on Nikon D3x00 series, Nikon D5x00 series, Fuji X-series, Sony A6x00 series, and many others), divide all these numbers by 1.5. On Micro Four-Thirds cameras (like those from Olympus and Panasonic), divide all these numbers by 2. In other words, I don't recommend using f/11 with a micro four-thirds camera, since it's equivalent to f/22 with a full-frame camera.

2. Lens Aberrations

Here's a fun one. For some reason, everyone wants to take sharp photos! One of the ways to do so is to minimize the visibility of lens aberrations. So, what are lens aberrations? Quite simply, they are image quality problems with a photo, caused by your lens.

Although most problems in photography are because of user error - things like missed focus, poor exposure, or a distracting composition - lens aberrations are entirely due to your equipment. They are fundamental, optical problems that you'll notice with any lens if you look too closely, although some lenses are better than others. For example, consider the image below:

What's going on here? In this crop, most of the lights look smeared rather than perfectly round. On top of that, the crop just isn't very sharp. That's lens aberration at work! The lights didn't look this blurry in the real world. My lens added this problem.

It's likely that your lenses are blurrier at certain apertures than others, and it's almost always blurrier in the corner of the image than the center. That's due to lens aberrations.

Aberrations can appear in several different forms. This article would be way too long if I explained every possible aberration in detail: vignetting, spherical aberration, field curvature, coma, distortion, color fringing, and more. Instead, it's more important to know why aberrations occur, including how your aperture setting can reduce them.

It starts with a simple fact: designing lenses is difficult. When the manufacturer fixes one problem, another tends to appear. It's no surprise that modern lens designs are extremely complex.

Unfortunately, even today's lenses aren't perfect. They tend to work fine in the center of an image, but everything gets worse near the edges. That's because lenses are especially difficult to design around the corners.

Here's a diagram that explains what I mean:

And that brings us to aperture.

Many people don't realize a simple fact about aperture: it literally blocks the light transmitted by the edges of your lens. (This doesn't lead to black corners in your photos, because the center regions of a lens can still transmit light to the edges of your camera sensor.)

As your aperture closes, more and more light from the sides of your lens will be blocked, never making it to your camera sensor. Only the light from the center area will pass through and form your photo! As the diagram above shows, this central area is far easier for camera manufacturers to design. The end result is that your photos will have fewer aberrations at smaller and smaller apertures.

How does this look in practice? See the photos below (heavy crops from the top-left corner):

What you're seeing above may look like an increase in sharpness, but it's really a decrease in aberrations. The end result? At f/5.6 on this particular lens, my photo is much sharper than at f/1.4.

Here's a key question: How does this balance out with diffraction, which harms sharpness increasingly more as your aperture gets narrower and narrower?

In practice, the answer is that most lenses end up sharpest around f/4, f/5.6, or f/8. Those "medium" apertures are small enough to block light from the edges of a lens, but they aren't so small that diffraction is a significant problem. However, you'll want to test this on your own equipment.

Of course, you can still take good photos at large apertures like f/1.4 or f/2. As I mentioned earlier, portrait photographers sometimes pay thousands of dollars to get a lens exactly for that purpose! So, don't lock your lens to f/5.6 just because it gives you a tad more corner sharpness up close. It's better to choose an aperture that gives you the right artistic look to the image.

Side Note

Some types of aberrations don't change much as you stop down, or they may even get slightly worse. Axial chromatic aberration, for example - color fringes near the edges of your frame - often work that way. This is normal. It happens because a small aperture doesn't inherently reduce aberrations; it simply blocks light that has passed through the edges of your lens. So, naturally, if the edges aren't the source of your problem, you won't see an improvement by stopping down.

3. Starburst and Sunstar Effects

Starbursts, also called sunstars, are beautiful elements that you'll find in certain photographs. Despite the odd names - one a type of candy; the other a type of starfish - I always try to capture them in my landscape photos. Here's an example:

How does this work? Essentially, for every aperture blade in your lens, you'll end up with a sunbeam. This only happens if you photograph a small, bright point of light, such as the sun when it is partly blocked. This is fairly common in landscape photography. If you want the strongest possible starburst, use a small aperture. Whenever the sun is in my photo, I almost always set f/16 purely to capture this effect.

Also, the starburst effect looks different from lens to lens. It all depends upon your aperture blades. If your lens has six aperture blades, you'll get six sunbeams. If your lens has eight aperture blades, you'll get eight sunbeams. And, if your lens has nine aperture blades, you'll get eighteen sunbeams.

Wait, what?

That's no typo. You always end up with an even number of sunbeams. If your lens has an odd number of aperture blades, you'll get double the number of sunbeams.

It sounds strange, but the reason is actually quite simple. In lenses with an even number of aperture blades (and a fully symmetrical design), half of the sunbeams will overlap the other half. So, you don't see all of them in your final photo.

Here's a diagram to show what I mean:

Most Nikon lenses have seven or nine aperture blades, resulting in 14 and 18 sunbeams respectively. Most Canon lenses have eight aperture blades, resulting in eight sunbeams. I took the photo above using the Nikon 20mm f/1.8G lens, which has 7 aperture blades. That's why the image has 14 sunbeams.

It's not just the number of blades that matters, though - their shape is also important. Some aperture blades are rounded (which results in a more pleasant out-of-focus background blur), and others are straight. If your goal is to capture good starbursts, straight aperture blades typically produce more defined rays of light.

Again, some lenses are better than others in this regard. For the best results, find a lens that's known to have good starbursts, and then set it to a small aperture like f/16. That's going to give you the strongest definition in your starbursts.

Finally, there's one last related effect that I wanted to mention briefly. When you shoot into the sun, you might end up with flare in your photographs, as shown below. Depending upon your chosen aperture, the size and shape of this lens flare may change slightly. This isn't a big deal, but it still exists.

4. Small Aperture and Unwanted Elements

When you shoot through things such as fences, dirty windows, plants, and even water droplets on your lens, you'll probably be disappointed by photos taken with a small aperture.

Small apertures like f/11 and f/16 give you such a large depth of field that you may accidentally include elements that you don't want to be in focus! For example, if you're shooting at a waterfall or by the ocean, an aperture of f/16 could render a tiny water droplet on your lens into a distinct, ugly blob:

In cases like that, it's better just to use a wider aperture - something like f/5.6, perhaps - in order to capture the water droplet so out-of-focus that it doesn't even appear in your image. In this particular case, you could simply wipe the droplet off, but that's not possible if you're shooting through something like a dirty window.

Side Note

You might have realized that this section is really just an extension of depth of field, and that's true! However, it's a bit of a special case, so I decided to mention it specifically.

Another example of shooting through things is when a piece of dust lands on your camera sensor. Unfortunately, as you change lenses, this is very common. Dust specks on your camera sensor will show up very clearly at small apertures like f/16, even if they're invisible at something larger, like f/4.

Luckily, they are very easy to remove in post-production software like Photoshop or Lightroom, though it can be annoying if you have to remove dozens of them from a single photo. That's why you should always keep your camera sensor clean.

5. Changes to Your Bokeh

What is bokeh? It's simply the quality of your background blur. If you take a lot of portraits, macro photos, or wildlife photos, you'll end up with out-of-focus backgrounds in most of your images. Naturally, you want them to look as good as possible! Different aperture settings will change the shape of your background blur.

Why is that? It's because the background blur of your photographs always takes on the shape of your aperture blades. So, if your aperture blades are shaped like a heart, you'll end up with heart-shaped background blur. Most of the time, that would qualify as distracting bokeh, although it's kind of cute in this photo of two fake tortoises:

On some lenses, aperture blades change shape a bit as they open and close. Large aperture settings (such as f/1.8) often have rounder background blur compared to smaller aperture settings. You'll also get more background blur at large apertures, since your depth of field is thinner.

If bokeh is something that matters to you, you'll want to test this on your particular lenses. Take some out-of-focus photos of a busy scene, each using a different aperture setting, and see which one looks the best. Most of the time, it will be the lens's widest aperture, but not always.

6. Focus Shift Issues

With certain lenses - even if you're in manual focus, and you don't move your focus ring - your point of focus may shift as you use smaller and smaller apertures.

Obviously, this isn't ideal. How do you tell if your lens has problematic focus shift? It's pretty easy. Here are the steps:

Put your camera on a tripod, and set your lens to manual focus.

Find an object with small details that extends backwards, and focus at the center of it. A table with a tablecloth works well.

Double check: When take a test photo and magnify it, you should see pixel-level details, as well as portions of the photo that are clearly out of focus.

Take a photo at your lens's widest aperture, and then at progressively smaller apertures. Be sure not to move your focus ring, and double check that you are using manual focus.

On your computer, zoom into 100% on these photos and see if the sharpest point of focus moves continuously farther back as you stop down. The more it moves, the worse your focus shift issue is.

You're done!

If your lens has extreme levels of focus shift, you'll want to compensate for it:

With your widest aperture, just focus like normal.

As you stop down the aperture, make sure to set your aperture first, then focus second (rather than focusing first). On DSLRs, we recommend focusing in live view at these apertures, because the viewfinder always focuses at the widest aperture. Mirrorless camera users don't need to worry about that.

With small apertures like f/8 and beyond, your depth of field will be large enough to hide any focus shift problems, so just focus like normal.

Side Note

When it comes down to it, focus shift is just another type of lens aberration. The edges of your lens may not focus light the same as the center, so, by stopping down - again, blocking light from the edges - your focus point changes slightly. That's the underlying reason for this effect.

7. Ease of Focusing

The autofocus system on your camera doesn't work well unless it receives plenty of light.

So, if you're shooting with a cheaper lens like a 70-300mm f/4.5-5.6, the largest aperture isn't bright enough to gather a lot of light. Focusing in dark conditions may be impacted. This is part of why a lot of pro photographers will use a more expensive lens like a 70-200mm f/2.8 instead.

You'll also enjoy a brighter viewfinder (on a DSLR) or a less noisy viewfinder (on a mirrorless camera) if your lens has a large maximum aperture. If you shoot a lot in low light, this can make it much easier to focus and compose your images.

8. Flash Exposure

When using speedlights or any kind of strobes, it is important to remember that aperture takes on a whole different role of controlling flash exposure. While shutter speed's role becomes controlling ambient light, aperture has an outsized impact on how much light from your flash is captured. Even though it's just a subset of exposure, we wanted to include it in this section, since flash is tightly correlated to lens aperture.

A Chart of Everything Aperture Does

Once you understand the information above, you will know everything aperture does to your photos. However, it may take a few re-reads of this article before it's all completely clear.

Practice is your best friend. Go outside, take some photos, and get a feel for aperture yourself.

If it helps, I compiled the main information in this article into a chart. This chart covers the most important effects of aperture in photography, as well as common terms that photographers use to describe their settings.

Note that to make this diagram easier to see, I did not darken or lighten any of the sample illustrations (as would occur in the real world). Instead, I simply wrote "brightest" through "darkest":

Although this chart is intentionally simplified, it covers all the basics that you need to know. Feel free to download and print this chart if you find it useful. Just right-click on the image, then select "save as," and pick the location where you want to store it.

Aperture FAQ

We put together some of the most frequently-asked questions related to aperture below.
How Does Aperture Affect Bokeh?
Bokeh refers to the quality of out-of-focus highlights of the image rendered by the camera lens. Using the maximum aperture of the lens will typically yield circular background highlights of large size, whereas stopping down the lens will typically result in highlights looking smaller and taking different shapes such as heptagon. These shapes depend on the number of aperture blades and their roundness. Here is an image of a 50mm f/1.4 prime lens stopped down to f/2.8 and f/4 apertures:

How Does Aperture Affect Sharpness?
Aperture is clearly a crucial setting in photography and it is possibly the single most important setting of all. Aperture affects several different parts of your photo, but you'll get the hang of everything fairly quickly. For a quick summary, a narrow aperture...

Makes your photos darker

Gives you more depth of field

Increases blur from diffraction

Decreases blur from most lens aberrations

Makes sensor dust more visible

Heightens the intensity of starbursts

...whereas a wide aperture does the opposite.

Soon, this won't be something that you even need to think about; you'll remember it all naturally. Personally, if I want a starburst effect in my photos, I immediately know to use an aperture of f/16. When I need as much light as possible, I set a larger aperture like f/2.8 or f/2 without a second thought. It doesn't take too much practice to get to that point.

With how important aperture is, it shouldn't be a surprise that, at Photography Life, we shoot in aperture-priority or manual mode all of the time. We simply never want the camera to select the aperture for us. It's just too important, and it is one of those basic settings that every beginner or advanced photographer needs to know in order to take the best possible images.

As always, it's best if you learn all this for yourself. Find something spectacular to capture, and put your new knowledge into practice. The more photos you take, the more you'll learn. Aperture is no exception.

Below are some other related posts you might enjoy:

Hopefully, you found that this article explains the basics of aperture in a way that is understandable and straightforward.

If you are ready to move on, the next important camera setting to learn is ISO, which we explain in Chapter 5 of our Photography Basics guide.

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What is Aperture? Understanding Aperture in Photography

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Aperture is one of the three pillars of photography, and certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

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Understanding Aperture – A Beginner’s Guide

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Understanding Aperture – A Beginner’s Guide

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- Valarie

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Aperture is one of the three pillars of photography (the other two being Shutter Speed and ISO, which are two other chapters in our Photography Basics guide). Of the three, aperture is certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

What is Aperture?

Aperture can be defined as the opening in a lens through which light passes to enter the camera. It is an easy concept to understand if you just think about how your eyes work. As you move between bright and dark environments, the iris in your eyes either expands or shrinks, controlling the size of your pupil.

In photography, the "pupil" of your lens is called aperture. You can shrink or enlarge the size of the aperture to allow more or less light to reach your camera sensor. The image below shows an aperture in a lens:

Aperture can add dimension to your photos by controlling depth of field. At one extreme, aperture gives you a blurred background with a beautiful shallow focus effect. This is very popular for portrait photography.

At the other extreme, it will give you sharp photos from the nearby foreground to the distant horizon. Landscape photographers use this effect a lot.

On top of that, the aperture you choose also alters the exposure of your images by making them brighter or darker.

Aperture Explained in Video

If you prefer to understand how aperture works visually, we put together a video for you that goes through most of the basics. In the video, we go through what aperture is, how it works, and every effect that aperture has in photography. (These points are also covered further down in this article.)

How Aperture Affects Exposure

Aperture has several effects on your photographs. Perhaps the most obvious is the brightness, or exposure, of your images. As aperture changes in size, it alters the overall amount of light that reaches your camera sensor - and therefore the brightness of your image.

A large aperture (a wide opening) will pass a lot of light, resulting in a brighter photograph. A small aperture does just the opposite, making a photo darker. Take a look at the illustration below to see how it affects exposure:

In a dark environment - such as indoors or at night - you will probably want to select a large aperture to capture as much light as possible. This is the same reason why people's pupils dilate when it starts to get dark; pupils are the aperture of our eyes.

How Aperture Affects Depth of Field

The other critical effect of aperture is depth of field. Depth of field is the amount of your photograph that appears sharp from front to back. Some images have a "thin" or "shallow" depth of field, where the background is completely out of focus. Other images have a "large" or "high" depth of field, where both the foreground and background are sharp.

For example, here is an image with a shallow depth of field:

In the image above, you can see that the girl is in focus and appears sharp, while the background is completely out of focus. My choice of aperture played a big role here. I specifically used a large aperture in order to create a shallow focus effect (yes, the larger your aperture, the bigger this effect). This helped me bring the attention of the viewer to the subject, rather than busy background. Had I used a narrower aperture, the subject would not be separated from the background as effectively.

One trick to remember this relationship: a large aperture results in a large amount of both foreground and background blur. This is often desirable for portraits, or general photos of objects where you want to isolate the subject. Sometimes you can frame your subject with foreground objects, which will also look blurred relative to the subject, as shown in the example below:

Quick Note: The appearance of the out-of-focus areas (AKA whether it looks good or not) is often referred to as " bokeh". Bokeh is the property of the lens, and some lenses have better bokeh than others. This article explains how to get better bokeh as a photographer. Even though some lenses are better than others, almost all lenses are capable of a nice shallow focus effect if you use a large aperture and get close enough to your subject.

On the other hand, a small aperture results in a small amount of background blur, which is typically ideal for some types of photography such as landscape and architecture. In the landscape photo below, I used a small aperture to ensure that both my foreground and background were as sharp as possible from front to back:

Here is a quick comparison that shows the difference between using a large vs a small aperture and what it does to your depth of field:

As you can see, in the photograph on the left, only the head of the lizard appears in focus and sharp, while the background and foreground are both transitioning into blur. Meanwhile, the photo on the right has everything from front to back appearing in focus. This is what using large vs small aperture does to photographs.

What Are F-Stop and F-Number?

So far, we have only discussed aperture in general terms like large and small. However, it can also be expressed as a number known as "f-number" or " f-stop ", with the letter "f" appearing before the number, such as f/8.

Most likely, you have noticed aperture written this way on your camera before. On your LCD screen or viewfinder, your aperture will usually look something like this: f/2, f/3.5, f/8, and so on. Some cameras omit the slash and write f-stops like this: f2, f3.5, f8, and so on. For example, the Nikon camera below is set to an aperture of f/8:

So, f-stops are a way of describing the size of the aperture for a particular photo. If you want to find out more about this subject, we have a comprehensive article on f-stop that explains why it's written that way and is worth checking out.

Large vs Small Aperture

There's a catch - one important part of aperture that confuses beginning photographers more than anything else. This is something you really need to pay attention to and get correct: Small numbers represent large apertures, and large numbers represent small apertures!

That's not a typo. For example, f/2.8 is larger than f/4 and much larger than f/11. Most people find this awkward, since it goes against our basic intuition. Nevertheless, this is a fact of photography. Take a look at this chart:

This causes a huge amount of confusion among photographers, because it's completely the reverse of what you would expect at first. However, there is a reasonable and simple explanation that should make it much clearer to you: Aperture is a fraction.

When you are dealing with an f-stop of f/16, for example, you can think of it like the fraction 1/16th. Hopefully, you already know that a fraction like 1/16 is clearly much smaller than the fraction 1/4. For this exact reason, an aperture of f/16 is smaller than f/4. Looking at the front of your camera lens, this is what you'd see:

So, if photographers recommend a large aperture for a particular type of photography, they're telling you to use something like f/1.4, f/2, or f/2.8. And if they suggest a small aperture for one of your photos, they're recommending that you use something like f/8, f/11, or f/16.

How to Pick the Right Aperture

Now that you're familiar with large vs small apertures, how do you know what aperture to use for your photos? Let's revisit two of the most important effects of aperture: exposure and depth of field. First, here is a quick diagram to refresh your memory on how aperture affects the exposure of an image:

If you've read the prior chapter in our Photography Basics guide covering shutter speed, you already know that aperture isn't the only way to change how bright a photo is. Nevertheless, it plays an important role. In the graphic above, if I didn't allow myself to change any other camera settings like shutter speed or ISO, the optimal aperture would be f/5.6.

In a darker environment, where you aren't capturing enough light, the optimal aperture would change. For example, you may want to use a large aperture like f/2.8 at night, just like how our eye's pupils dilate to capture every last bit of light:

As for depth of field, recall that a large aperture value like f/2.8 will result in a large amount of background blur (ideal for shallow focus portraits), while values like f/8, f/11, or f/16 will give you a lot more depth of field (ideal for landscapes and architectural photography).

In fact, depth of field is the part of aperture that I recommend thinking about the most. My process for almost every photo I take goes like this:

Ask myself how much depth of field I want

Set an aperture that achieves it

Set a shutter speed that makes my photo the proper brightness

If that shutter speed leads to unsharp photos thanks to too much motion blur, dial back the shutter speed and raise my ISO instead

Win photo contest :)

Here is a quick chart that lays out everything we've covered so far:

Setting Aperture in Your Camera

If you haven't guessed it already, we highly recommend selecting your aperture manually as a photographer. If you allow the camera to set it automatically, you are likely to end up with the completely wrong depth of field in your image.

There are two modes in photography which allow you to select the aperture manually. These are aperture-priority mode and manual mode. Aperture-priority mode is written as "A" or "Av" on most cameras, while manual is written as "M." Usually, you can find these on the top dial of your camera (read more also in our article on camera modes):

In aperture-priority mode, you select the desired aperture, and the camera automatically selects your shutter speed. You can select ISO manually or automatically. Aperture priority mode is great for everyday photography, where you rarely need to worry about any camera settings other than aperture. It's what I use 95% of the time even for professional landscape and portrait photography.

In manual mode, you select both aperture and shutter speed manually. (ISO can again be manual or auto.) Manual mode takes more time and usually gives you the same results as aperture priority anyway. It's only needed in special situations where you need a consistent exposure from shot to shot, or when the camera's meter is messing up. I use it for Milky Way photography and for portraiture with flash.

Minimum and Maximum Aperture of Lenses

Every lens has a limit on how large or how small the aperture can get. If you take a look at the specifications of your lens, it should say what the maximum and minimum apertures are. For almost everyone, the maximum aperture will be more important, because it tells you how much light the lens can gather at its maximum (basically, how dark of an environment you can take photos - and how much of a shallow focus effect you can achieve).

A lens that has a maximum aperture of f/1.4 or f/1.8 is considered to be a "fast" lens, because it can pass through more light than, for example, a lens with a "slow" maximum aperture of f/4.0. That's why lenses with large apertures usually cost more.

By comparison, the minimum aperture is not that important, because almost all modern lenses can provide at least f/16 at the minimum. You will rarely need anything smaller than that for day-to-day photography.

With some zoom lenses, the maximum aperture will change as you zoom in and out. For example, with the Nikon 18-55mm f/3.5-5.6 AF-P lens, the largest aperture shifts gradually from f/3.5 at the wide end to just f/5.6 at the longer focal lengths. More expensive zooms tend to maintain a constant maximum aperture throughout their zoom range, like the Nikon 24-70mm f/2.8. Prime lenses also tend to have larger maximum apertures than zoom lenses, which is one of their major benefits.

The maximum aperture of a lens is so important that it's included in the name of the lens itself. Sometimes, it will be written with a colon rather than a slash, but it means the same thing (like the Nikon 50mm 1:1.4G below).

Examples of Which Aperture to Use

Now that we have gone through a thorough explanation of how aperture works and how it affects your images, let's take a look at the situations where you'd want to use various f-stops.

f/0.95 - f/1.4 - Such "fast" maximum apertures are only available on premium prime lenses, allowing them to gather as much light as possible. This makes them ideal for any kind of low-light photography (such as photographing the night sky, wedding receptions, portraits in dimly-lit rooms, corporate events, etc). With such wide f-stops, you will get very shallow depth of field at close distances, where the subject will appear separated from the background.

f/1.8 - f/2.0 - Some enthusiast-grade prime lenses are limited to f/1.8, which still has very good low-light capabilities. Also, if your purpose is to yield aesthetically-pleasing images with shallow focus, these lenses be of tremendous value. Shooting between f/1.8 and f/2 typically turns your backgrounds nice and creamy for portraiture and other similar types of photography.

f/2.8 - f/4 - Most zoom lenses are limited to a maximum aperture of f/2.8 to f/4 at best. While they are not as capable as f/1.4 lenses in terms of light-gathering capabilities, they are still enough to shoot in reasonably low light conditions, especially if the lens or camera has image stabilization. You'll get some subject separation at these apertures, but usually not enough to make the background completely fuzzy. Such apertures are great for travel, sports, and wildlife photography.

f/5.6 - f/8 - This is the right starting point for most landscape and architectural photography. It's also ideal for documentary and portrait photography where you don't want a blurry background. Also, most lenses are sharpest around f/5.6, which doesn't matter as much as getting the right depth of field, but is still nice.

f/11 - f/16 - Typically used for photographing scenes where as much depth of field as possible is needed, like macro photography or landscape photography with a nearby foreground. Even though these apertures offer more depth of field, they do lose some low-level sharpness due to the effect of lens diffraction.

f/22 and smaller - Only shoot at such small apertures if you know what you are doing. Sharpness suffers greatly at f/22 and smaller apertures because of diffraction, so you should avoid using them when possible. If you need to get more depth of field, it is usually best to move away from your subject or use a focus stacking technique instead.

You've made it this far, but are you willing to learn more about aperture? So far we have only touched the basics, but aperture does so much more to your photographs. Let's take a closer look.

Everything Aperture Does to Your Photos

Ever wondered how else aperture affects your photographs aside from brightness and depth of field? In this part of the article, we will go through all other ways aperture impacts your images, from sharpness to sunstars, and tell you exactly why each matters.

Before diving into too many specifics, here's a quick list of everything aperture affects in photography:

The brightness / exposure of your photos and depth of field, as discussed so far

Sharpness loss due to diffraction

Sharpness loss due to lens quality

Starburst effects on bright lights

Visibility of camera sensor dust specks

The quality of background highlights (bokeh)

Focus shift on some lenses

Ability to focus in low light (under some conditions)

Controlling the amount of light from the flash

1. The Negative Effect of Diffraction

So, if you're a landscape photographer who wants everything as sharp as possible, you should use your lens's smallest aperture, like f/22 or f/32 to get maximum depth of field, right?

No!

If we go back and take a close look at the photo of the lizard from earlier in this article, where I used apertures of f/4 and f/32, you can see how diffraction is making the second shot less sharp. Here are the images when zoomed in to 100% view:

Here, you're seeing an effect called diffraction. Physics majors will know what I'm talking about, but diffraction is a foreign concept to most people. So, what is it?

Diffraction is actually quite simple. When you use a tiny aperture like f/32, you literally squeeze the light that passes through your lens. It ends up interfering with itself, growing blurrier, and resulting in photos that are noticeably less sharp.

At what aperture does diffraction start to become an issue? It depends upon a number of factors, including the size of your camera sensor and the size of your final print. Personally, on my full-frame camera, I see hints of diffraction at f/8, but it's not enough to bother me. I actually use even smaller apertures like f/11 and f/16 all the time when I have a close foreground in landscape photography. However, I try to avoid f/22 or smaller, since I lose too much detail at that point.

Diffraction isn't necessarily a huge problem, but it exists. Don't be afraid to take pictures at f/11 or f/16 just because you lose a little bit of sharpness. In many cases, the added depth of field is worth the tradeoff.

In macro photography, diffraction can be a bit more of a problem close-focusing actually makes your effective aperture a lot smaller than it really is. Although the math behind that gets a bit complicated, basically, shooting at f/11 at macro distances will show diffraction a lot more compared to if you're shooting a landscape at f/11. In other words, keep an eye out for diffraction when shooting macro.

Side Note

If your camera has a smaller sensor or a very high pixel density, you'll see diffraction sooner. On APS-C sensors (like on Nikon D3x00 series, Nikon D5x00 series, Fuji X-series, Sony A6x00 series, and many others), divide all these numbers by 1.5. On Micro Four-Thirds cameras (like those from Olympus and Panasonic), divide all these numbers by 2. In other words, I don't recommend using f/11 with a micro four-thirds camera, since it's equivalent to f/22 with a full-frame camera.

2. Lens Aberrations

Here's a fun one. For some reason, everyone wants to take sharp photos! One of the ways to do so is to minimize the visibility of lens aberrations. So, what are lens aberrations? Quite simply, they are image quality problems with a photo, caused by your lens.

Although most problems in photography are because of user error - things like missed focus, poor exposure, or a distracting composition - lens aberrations are entirely due to your equipment. They are fundamental, optical problems that you'll notice with any lens if you look too closely, although some lenses are better than others. For example, consider the image below:

What's going on here? In this crop, most of the lights look smeared rather than perfectly round. On top of that, the crop just isn't very sharp. That's lens aberration at work! The lights didn't look this blurry in the real world. My lens added this problem.

It's likely that your lenses are blurrier at certain apertures than others, and it's almost always blurrier in the corner of the image than the center. That's due to lens aberrations.

Aberrations can appear in several different forms. This article would be way too long if I explained every possible aberration in detail: vignetting, spherical aberration, field curvature, coma, distortion, color fringing, and more. Instead, it's more important to know why aberrations occur, including how your aperture setting can reduce them.

It starts with a simple fact: designing lenses is difficult. When the manufacturer fixes one problem, another tends to appear. It's no surprise that modern lens designs are extremely complex.

Unfortunately, even today's lenses aren't perfect. They tend to work fine in the center of an image, but everything gets worse near the edges. That's because lenses are especially difficult to design around the corners.

Here's a diagram that explains what I mean:

And that brings us to aperture.

Many people don't realize a simple fact about aperture: it literally blocks the light transmitted by the edges of your lens. (This doesn't lead to black corners in your photos, because the center regions of a lens can still transmit light to the edges of your camera sensor.)

As your aperture closes, more and more light from the sides of your lens will be blocked, never making it to your camera sensor. Only the light from the center area will pass through and form your photo! As the diagram above shows, this central area is far easier for camera manufacturers to design. The end result is that your photos will have fewer aberrations at smaller and smaller apertures.

How does this look in practice? See the photos below (heavy crops from the top-left corner):

What you're seeing above may look like an increase in sharpness, but it's really a decrease in aberrations. The end result? At f/5.6 on this particular lens, my photo is much sharper than at f/1.4.

Here's a key question: How does this balance out with diffraction, which harms sharpness increasingly more as your aperture gets narrower and narrower?

In practice, the answer is that most lenses end up sharpest around f/4, f/5.6, or f/8. Those "medium" apertures are small enough to block light from the edges of a lens, but they aren't so small that diffraction is a significant problem. However, you'll want to test this on your own equipment.

Of course, you can still take good photos at large apertures like f/1.4 or f/2. As I mentioned earlier, portrait photographers sometimes pay thousands of dollars to get a lens exactly for that purpose! So, don't lock your lens to f/5.6 just because it gives you a tad more corner sharpness up close. It's better to choose an aperture that gives you the right artistic look to the image.

Side Note

Some types of aberrations don't change much as you stop down, or they may even get slightly worse. Axial chromatic aberration, for example - color fringes near the edges of your frame - often work that way. This is normal. It happens because a small aperture doesn't inherently reduce aberrations; it simply blocks light that has passed through the edges of your lens. So, naturally, if the edges aren't the source of your problem, you won't see an improvement by stopping down.

3. Starburst and Sunstar Effects

Starbursts, also called sunstars, are beautiful elements that you'll find in certain photographs. Despite the odd names - one a type of candy; the other a type of starfish - I always try to capture them in my landscape photos. Here's an example:

How does this work? Essentially, for every aperture blade in your lens, you'll end up with a sunbeam. This only happens if you photograph a small, bright point of light, such as the sun when it is partly blocked. This is fairly common in landscape photography. If you want the strongest possible starburst, use a small aperture. Whenever the sun is in my photo, I almost always set f/16 purely to capture this effect.

Also, the starburst effect looks different from lens to lens. It all depends upon your aperture blades. If your lens has six aperture blades, you'll get six sunbeams. If your lens has eight aperture blades, you'll get eight sunbeams. And, if your lens has nine aperture blades, you'll get eighteen sunbeams.

Wait, what?

That's no typo. You always end up with an even number of sunbeams. If your lens has an odd number of aperture blades, you'll get double the number of sunbeams.

It sounds strange, but the reason is actually quite simple. In lenses with an even number of aperture blades (and a fully symmetrical design), half of the sunbeams will overlap the other half. So, you don't see all of them in your final photo.

Here's a diagram to show what I mean:

Most Nikon lenses have seven or nine aperture blades, resulting in 14 and 18 sunbeams respectively. Most Canon lenses have eight aperture blades, resulting in eight sunbeams. I took the photo above using the Nikon 20mm f/1.8G lens, which has 7 aperture blades. That's why the image has 14 sunbeams.

It's not just the number of blades that matters, though - their shape is also important. Some aperture blades are rounded (which results in a more pleasant out-of-focus background blur), and others are straight. If your goal is to capture good starbursts, straight aperture blades typically produce more defined rays of light.

Again, some lenses are better than others in this regard. For the best results, find a lens that's known to have good starbursts, and then set it to a small aperture like f/16. That's going to give you the strongest definition in your starbursts.

Finally, there's one last related effect that I wanted to mention briefly. When you shoot into the sun, you might end up with flare in your photographs, as shown below. Depending upon your chosen aperture, the size and shape of this lens flare may change slightly. This isn't a big deal, but it still exists.

4. Small Aperture and Unwanted Elements

When you shoot through things such as fences, dirty windows, plants, and even water droplets on your lens, you'll probably be disappointed by photos taken with a small aperture.

Small apertures like f/11 and f/16 give you such a large depth of field that you may accidentally include elements that you don't want to be in focus! For example, if you're shooting at a waterfall or by the ocean, an aperture of f/16 could render a tiny water droplet on your lens into a distinct, ugly blob:

In cases like that, it's better just to use a wider aperture - something like f/5.6, perhaps - in order to capture the water droplet so out-of-focus that it doesn't even appear in your image. In this particular case, you could simply wipe the droplet off, but that's not possible if you're shooting through something like a dirty window.

Side Note

You might have realized that this section is really just an extension of depth of field, and that's true! However, it's a bit of a special case, so I decided to mention it specifically.

Another example of shooting through things is when a piece of dust lands on your camera sensor. Unfortunately, as you change lenses, this is very common. Dust specks on your camera sensor will show up very clearly at small apertures like f/16, even if they're invisible at something larger, like f/4.

Luckily, they are very easy to remove in post-production software like Photoshop or Lightroom, though it can be annoying if you have to remove dozens of them from a single photo. That's why you should always keep your camera sensor clean.

5. Changes to Your Bokeh

What is bokeh? It's simply the quality of your background blur. If you take a lot of portraits, macro photos, or wildlife photos, you'll end up with out-of-focus backgrounds in most of your images. Naturally, you want them to look as good as possible! Different aperture settings will change the shape of your background blur.

Why is that? It's because the background blur of your photographs always takes on the shape of your aperture blades. So, if your aperture blades are shaped like a heart, you'll end up with heart-shaped background blur. Most of the time, that would qualify as distracting bokeh, although it's kind of cute in this photo of two fake tortoises:

On some lenses, aperture blades change shape a bit as they open and close. Large aperture settings (such as f/1.8) often have rounder background blur compared to smaller aperture settings. You'll also get more background blur at large apertures, since your depth of field is thinner.

If bokeh is something that matters to you, you'll want to test this on your particular lenses. Take some out-of-focus photos of a busy scene, each using a different aperture setting, and see which one looks the best. Most of the time, it will be the lens's widest aperture, but not always.

6. Focus Shift Issues

With certain lenses - even if you're in manual focus, and you don't move your focus ring - your point of focus may shift as you use smaller and smaller apertures.

Obviously, this isn't ideal. How do you tell if your lens has problematic focus shift? It's pretty easy. Here are the steps:

Put your camera on a tripod, and set your lens to manual focus.

Find an object with small details that extends backwards, and focus at the center of it. A table with a tablecloth works well.

Double check: When take a test photo and magnify it, you should see pixel-level details, as well as portions of the photo that are clearly out of focus.

Take a photo at your lens's widest aperture, and then at progressively smaller apertures. Be sure not to move your focus ring, and double check that you are using manual focus.

On your computer, zoom into 100% on these photos and see if the sharpest point of focus moves continuously farther back as you stop down. The more it moves, the worse your focus shift issue is.

You're done!

If your lens has extreme levels of focus shift, you'll want to compensate for it:

With your widest aperture, just focus like normal.

As you stop down the aperture, make sure to set your aperture first, then focus second (rather than focusing first). On DSLRs, we recommend focusing in live view at these apertures, because the viewfinder always focuses at the widest aperture. Mirrorless camera users don't need to worry about that.

With small apertures like f/8 and beyond, your depth of field will be large enough to hide any focus shift problems, so just focus like normal.

Side Note

When it comes down to it, focus shift is just another type of lens aberration. The edges of your lens may not focus light the same as the center, so, by stopping down - again, blocking light from the edges - your focus point changes slightly. That's the underlying reason for this effect.

7. Ease of Focusing

The autofocus system on your camera doesn't work well unless it receives plenty of light.

So, if you're shooting with a cheaper lens like a 70-300mm f/4.5-5.6, the largest aperture isn't bright enough to gather a lot of light. Focusing in dark conditions may be impacted. This is part of why a lot of pro photographers will use a more expensive lens like a 70-200mm f/2.8 instead.

You'll also enjoy a brighter viewfinder (on a DSLR) or a less noisy viewfinder (on a mirrorless camera) if your lens has a large maximum aperture. If you shoot a lot in low light, this can make it much easier to focus and compose your images.

8. Flash Exposure

When using speedlights or any kind of strobes, it is important to remember that aperture takes on a whole different role of controlling flash exposure. While shutter speed's role becomes controlling ambient light, aperture has an outsized impact on how much light from your flash is captured. Even though it's just a subset of exposure, we wanted to include it in this section, since flash is tightly correlated to lens aperture.

A Chart of Everything Aperture Does

Once you understand the information above, you will know everything aperture does to your photos. However, it may take a few re-reads of this article before it's all completely clear.

Practice is your best friend. Go outside, take some photos, and get a feel for aperture yourself.

If it helps, I compiled the main information in this article into a chart. This chart covers the most important effects of aperture in photography, as well as common terms that photographers use to describe their settings.

Note that to make this diagram easier to see, I did not darken or lighten any of the sample illustrations (as would occur in the real world). Instead, I simply wrote "brightest" through "darkest":

Although this chart is intentionally simplified, it covers all the basics that you need to know. Feel free to download and print this chart if you find it useful. Just right-click on the image, then select "save as," and pick the location where you want to store it.

Aperture FAQ

We put together some of the most frequently-asked questions related to aperture below.
How Does Aperture Affect Bokeh?
Bokeh refers to the quality of out-of-focus highlights of the image rendered by the camera lens. Using the maximum aperture of the lens will typically yield circular background highlights of large size, whereas stopping down the lens will typically result in highlights looking smaller and taking different shapes such as heptagon. These shapes depend on the number of aperture blades and their roundness. Here is an image of a 50mm f/1.4 prime lens stopped down to f/2.8 and f/4 apertures:

How Does Aperture Affect Sharpness?
Aperture is clearly a crucial setting in photography and it is possibly the single most important setting of all. Aperture affects several different parts of your photo, but you'll get the hang of everything fairly quickly. For a quick summary, a narrow aperture...

Makes your photos darker

Gives you more depth of field

Increases blur from diffraction

Decreases blur from most lens aberrations

Makes sensor dust more visible

Heightens the intensity of starbursts

...whereas a wide aperture does the opposite.

Soon, this won't be something that you even need to think about; you'll remember it all naturally. Personally, if I want a starburst effect in my photos, I immediately know to use an aperture of f/16. When I need as much light as possible, I set a larger aperture like f/2.8 or f/2 without a second thought. It doesn't take too much practice to get to that point.

With how important aperture is, it shouldn't be a surprise that, at Photography Life, we shoot in aperture-priority or manual mode all of the time. We simply never want the camera to select the aperture for us. It's just too important, and it is one of those basic settings that every beginner or advanced photographer needs to know in order to take the best possible images.

As always, it's best if you learn all this for yourself. Find something spectacular to capture, and put your new knowledge into practice. The more photos you take, the more you'll learn. Aperture is no exception.

Below are some other related posts you might enjoy:

Hopefully, you found that this article explains the basics of aperture in a way that is understandable and straightforward.

If you are ready to move on, the next important camera setting to learn is ISO, which we explain in Chapter 5 of our Photography Basics guide.

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What is Aperture? Understanding Aperture in Photography

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Aperture is one of the three pillars of photography, and certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

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-Woo Jin

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Depth of Field

Depth of Field (DOF) is the front-to-back zone of a photograph in which the image is razor sharp.

As soon as an object (person, thing) falls out of this range, it begins to lose focus at an accelerating degree the farther out of the zone it falls; e.g. closer to the lens or deeper into the background. With any DOF zone, there is a Point of Optimum focus in which the object is most sharp.

There are two ways to describe the qualities of depth of field - shallow DOF or deep DOF. Shallow is when the included focus range is very narrow, a few inches to several feet. Deep is when the included range is a couple of yards to infinity. In both cases DOF is measured in front of the focus point and behind the focus point.

DOF is determined by three factors - aperture size, distance from the lens, and the focal length of the lens. Let's look at how each one works.

Aperture

The aperture is the opening at the rear of the lens that determines how much light travels through the lens and falls on the image sensor.

The size of the aperture's opening is measured in f-stops - one of two sets of numbers on the lens barrel (the other being the focusing distance). The f-stops work as inverse values, such that a small f/number (say f/2.8) corresponds to a larger or wider aperture size, which results in a shallow depth of field; conversely a large f/number (say f/16) results in a smaller or narrower aperture size and therefore a deeper depth of field.

Small vs Large Aperture

Manipulating the aperture is the easiest and most often utilized means to adjust Depth of Field.

To achieve a deep, rich and expansive DOF, you'll want to set the f-stop to around f/11 or higher. You may have seen this principle demonstrated when you look at photos taken outside during the brightest time of the day. In such a case, the camera is typically set at f/16 or higher (that Sunny 16 Rule) and the Depth of Field is quite deep - perhaps several yards in front of and nearly to infinity beyond the exact focus point.

Let's take a look at these two photos as examples. The left side of the photo has an expansive DOF, most likely shot around noon (notice the short, but strong shadows), with an f/22 aperture. The right side of the photo has an extremely shallow DOF; probably an f/2.8 aperture setting. However, to achieve an identical proper exposure, the shutter speed is probably closer to 1/1000th to compensate for the increased amount of light entering the lens at f/2.8.

Aperture Range

The aperture range identifies the widest to smallest range of lens openings, i.e. f/1.4 (on a super-fast lens) to f/32, with incremental "stops" in between (f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, and f/22).

Each f-number is represents one "stop" of light, a stop is a mathematical equation (which is the focal length of the lens divided by the diameter of the aperture opening) that determines how much light that enters the lens regardless of the length of the lens. Such that an f/4 on a 50mm has smaller opening than an f/4 on a 200mm, but an equivalent amount of light travels through both lenses to reach the image sensor thus providing the same exposure.

Each movement up the range (say f/2 to f.2.8) reduces the amount of light by one-half and each movement down the range (say f/11 to f/8) doubles the amount of light passing through the lens. It's important to understand this concept and how it affects exposure because it works in tandem with the shutter speed (we'll discuss this in another section) to establish a given exposure value.

Basically, when you change the aperture size one stop, you have to shift the shutter speed one stop in the opposite direction to maintain a consistent exposure... and this change in aperture alters the depth of field (DOF) accordingly.

Distance from the Lens

The last element affecting depth of field is the distance of the subject from the lens - you can adjust the DOF by changing that distance.

For example, the closer an object is to the lens (and the focus is set on that object) the shallower the DOF. Conversely, the reverse is true - the farther away an object is and focused on, the deeper the DOF. Changing the distance to subject is the least practical way to manipulate the depth of field, and by changing the distance from a subject to the lens, you immediately change your image's composition. To maintain the compositional integrity of the shot, but still have the change in DOF from a distance, you can change the focal length (either by changing lenses or zooming in).

Why does changing the focal length negate the effects on DOF? This is because the visual properties of a given lens either provide either greater DOF (shorter lenses) or shallower DOF (longer lenses). The physical properties of a lens at a given focal length also affect the depth of field. A shorter focal length lens (say 27mm) focused at 5 meters, set at f/4 has a deeper DOF (perhaps from 3 meters in front and 20 meters behind) than a longer focal length (say 300mm), also set at f/4 focused at 5 meters. The 300mm lens has a remarkably shallow depth of field.

Incidentally, to help you with this, every lens has a manual with a DOF chart for each f/stop and the major focusing distances. DOF is just a matter of physics, and it's important to grasp this concept.

Conclusion

Manipulation of depth of field is a good way to modify the characteristics of your photo, and manipulating the aperture is the ideal way to do this because it has little or no effect on composition.

You simply need to change the shutter speed (or change the light sensitivity - ISO) to compensate for the changes in the exposure from the adjustments to the f-number. Changes in distance and focal length also affect DOF, but these changes have trade-offs in terms of composition.

Therefore, changes to aperture are the best way to manipulate DOF without affecting a photo's composition.

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Focusing Basics | Aperture and Depth of Field

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Depth of Field (DOF) is the front-to-back zone of a photograph in which the image is razor sharp. As soon as an object (person, thing) falls out of this range, it begins to lose focus at an accelerating degree the farther out of the zone it falls; e.g.

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How different Aperture affects the picture

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How different Aperture affects the picture

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Image

-Kevin

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-Snow

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Understanding Depth of Field for Beginners

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Learn how depth of field (DoF), can enhance your photos and the three main factors that influence depth of field in photography.

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- Oscar

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Depth of field refers to the range of distance that appears acceptably sharp. It varies depending on camera type, aperture and focusing distance, although print size and viewing distance can also influence our perception of depth of field. This tutorial is designed to give a better intuitive and technical understanding for photography, and provides a depth of field calculator to show how it varies with your camera settings.

The depth of field does not abruptly change from sharp to unsharp, but instead occurs as a gradual transition. In fact, everything immediately in front of or in back of the focusing distance begins to lose sharpness - even if this is not perceived by our eyes or by the resolution of the camera.

CIRCLE OF CONFUSION

Since there is no critical point of transition, a more rigorous term called the " circle of confusion" is used to define how much a point needs to be blurred in order to be perceived as unsharp. When the circle of confusion becomes perceptible to our eyes, this region is said to be outside the depth of field and thus no longer "acceptably sharp." The circle of confusion above has been exaggerated for clarity; in reality this would be only a tiny fraction of the camera sensor's area.

When does the circle of confusion become perceptible to our eyes? An acceptably sharp circle of confusion is loosely defined as one which would go unnoticed when enlarged to a standard 8x10 inch print, and observed from a standard viewing distance of about 1 foot.

At this viewing distance and print size, camera manufacturers assume a circle of confusion is negligible if no larger than 0.01 inches (when enlarged). As a result, camera manufacturers use the 0.01 inch standard when providing lens depth of field markers (shown below for f/22 on a 50mm lens). In reality, a person with 20/20 vision or better can distinguish features 1/3 this size, and so the circle of confusion has to be even smaller than this to achieve acceptable sharpness throughout.

A different maximum circle of confusion also applies for each print size and viewing distance combination. In the earlier example of blurred dots, the circle of confusion is actually smaller than the resolution of your screen for the two dots on either side of the focal point, and so these are considered within the depth of field. Alternatively, the depth of field can be based on when the circle of confusion becomes larger than the size of your digital camera's pixels.

Note that depth of field only sets a maximum value for the circle of confusion, and does not describe what happens to regions once they become out of focus. These regions are also called "bokeh," from Japanese (pronounced bo-ké). Two images with identical depth of field may have significantly different bokeh, as this depends on the shape of the lens diaphragm. In reality, the circle of confusion is usually not actually a circle, but is only approximated as such when it is very small. When it becomes large, most lenses will render it as a polygonal shape with 5-8 sides.

CONTROLLING DEPTH OF FIELD

Although print size and viewing distance influence how large the circle of confusion appears to our eyes, aperture and focusing distance are the two main factors that determine how big the circle of confusion will be on your camera's sensor. Larger apertures (smaller F-stop number) and closer focusing distances produce a shallower depth of field. The following test maintains the same focus distance, but changes the aperture setting:

note: images taken with a 200 mm lens (320 mm field of view on a 35 mm camera)

CLARIFICATION: FOCAL LENGTH AND DEPTH OF FIELD

Note that focal length has not been listed as influencing depth of field, contrary to popular belief. Even though telephoto lenses appear to create a much shallower depth of field, this is mainly because they are often used to magnify the subject when one is unable to get closer. If the subject occupies the same fraction of the image (constant magnification) for both a telephoto and a wide angle lens, the total depth of field is virtually* constant with focal length! This would of course require you to either get much closer with a wide angle lens or much farther with a telephoto lens, as demonstrated in the following chart:

Focal Length (mm)

Focus Distance (m)

Depth of Field (m)

Note: Depth of field calculations are at f/4.0 on a camera with a 1.6X crop factor,
using a circle of confusion of 0.0206 mm.

Note how there is indeed a subtle change for the smallest focal lengths. This is a real effect, but is negligible compared to both aperture and focusing distance. Even though the total depth of field is virtually constant, the fraction of the depth of field which is in front of and behind the focus distance does change with focal length, as demonstrated below:

This exposes a limitation of the traditional DoF concept: it only accounts for the total DoF and not its distribution around the focal plane, even though both may contribute to the perception of sharpness. Note how a wide angle lens provides a more gradually fading DoF behind the focal plane than in front, which is important for traditional landscape photographs.

Longer focal lengths may also appear to have a shallower depth of field because they enlarge the background relative to the foreground (due to their narrower angle of view). This can make an out of focus background look even more out of focus because its blur has become enlarged. However, this is another concept entirely, since depth of field only describes the sharp region of a photo - not the blurred regions.

On the other hand, when standing in the same place and focusing on a subject at the same distance, a longer focal length lens will have a shallower depth of field (even though the pictures will frame the subject entirely differently). This is more representative of everyday use, but is an effect due to higher magnification, not focal length.

Depth of field also appears shallower for SLR cameras than for compact digital cameras, because SLR cameras require a longer focal length to achieve the same field of view (see the tutorial on digital camera sensor sizes for more on this topic).

* Technical Note: We describe depth of field as being virtually constant because there are limiting cases where this does not hold true. For focal distances resulting in high magnification, or very near the hyperfocal distance, wide angle lenses may provide a greater DoF than telephoto lenses. On the other hand, at high magnification the traditional DoF calculation becomes inaccurate due to another factor: pupil magnification. This reduces the DoF advantage for most wide angle lenses, and increases it for telephoto and macro lenses. At the other limiting case, near the hyperfocal distance, the increase in DoF arises because the wide angle lens has a greater rear DoF, and can thus more easily attain critical sharpness at infinity.

CALCULATING DEPTH OF FIELD

In order to calculate the depth of field, one needs to first decide on an appropriate value for the maximum allowable circle of confusion. This is based on both the camera type (sensor or film size), and on the viewing distance / print size combination. Needless to say, knowing what this will be ahead of time often isn't straightforward. Try out the depth of field calculator tool to help you find this for your specific situation.

DEPTH OF FOCUS & APERTURE VISUALIZATION

Another implication of the circle of confusion is the concept of depth of focus (also called the "focus spread"). It differs from depth of field because it describes the distance over which light is focused at the camera's sensor, as opposed to the subject:

Diagram depicting depth of focus versus camera aperture. The purple lines comprising the edge of each shaded region represent the extreme angles at which light could potentially enter the aperture. The interior of the purple shaded regions represents all other possible angles.

The key concept is this: when an object is in focus, light rays originating from that point converge at a point on the camera's sensor. If the light rays hit the sensor at slightly different locations (arriving at a disc instead of a point), then this object will be rendered as out of focus - and increasingly so depending on how far apart the light rays are.

OTHER NOTES

Why not just use the smallest aperture (largest number) to achieve the best possible depth of field? Other than the fact that this may require prohibitively long shutter speeds without a camera tripod, too small of an aperture softens the image by creating a larger circle of confusion (or " Airy disk") due to an effect called diffraction - even within the plane of focus. Diffraction quickly becomes more of a limiting factor than depth of field as the aperture gets smaller. Despite their extreme depth of field, this is also why "pinhole cameras" have limited resolution.

For macro photography (high magnification), the depth of field is actually influenced by another factor: pupil magnification. This is equal to one for lenses which are internally symmetric, although for wide angle and telephoto lenses this is greater or less than one, respectively. A greater depth of field is achieved (than would be ordinarily calculated) for a pupil magnification less than one, whereas the pupil magnification does not change the calculation when it is equal to one. The problem is that the pupil magnification is usually not provided by lens manufacturers, and one can only roughly estimate it visually.

OTHER WEBSITES & FURTHER READING

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Understanding Depth of Field in Photography

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Depth of field refers to the range of distance that appears acceptably sharp. It varies depending on camera type, aperture and focusing distance, although print size and viewing distance can also influence our perception of depth of field.

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http://www.canadiannaturephotographer.com/fstop.html

- Su

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			Depth
			of Field: One
			of the most important elements in photography.
			

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			Depth
			of Field: One
			of the most important elements in photography.
			

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http://www.mir.com.my/rb/photography/fototech/htmls/depth.html

myat kaung khant

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efˌstäp/

noun a camera setting corresponding to a particular f-number.

The ratio of the lens's focal length to the diameter of the entrance pupil. It is a dimensionless number that is a quantitative measure of lens speed, and an important concept in photography.

-David

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What is it? - Thomas

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So what exactly is an f-stop? Well, to put it in the very simplest terms, it is the opening that lets light into your camera. And so the numbers on the f-stop relate to the size of the opening that is letting light into your camera. F-stops are measured by a scale, and this is known as the f-stop scale. If you are not familiar with a camera, the f-stop numbers can be very confusing, as they do not seem to make any sense. F-stops are actually a measurement of the diameter of the aperture. Logically, they should be expressed as a fraction and this number would tell you the diameter, in millimeters, as a fraction of the actual focal length of the lens. So if you had a zoom set at 40mm with an aperture of f/8, the diameter of the aperture opening is 5mm (40 divided by 8).

Adding to this confusion, the numbers that correspond to different f-stops seem backwards, because an aperture of f/8 is actually smaller than an aperture of f/4. So, the larger the number, the smaller the opening. And the smaller the number, the larger the opening.

And then you get into the fact that most f-stop numbers are not a full number. They are an f/5.6, or an f/19, or an f/6.3, or an f/1.4. If you are not familiar with f-stops and aperture openings, none of this makes any sense. These numbers depict half stops and third stops, as well as full f-stops.

The typical range for f-stops on a camera, progressing from a wide setting to a small setting is f/4, f/5.6, f/8, f/11, and f/16. Some lenses will have a wider range and may offer half stops and/or third stops.

Another funny thing about f-stops, is if you halve the number of the f-stop, the aperture lets in a quarter amount of light, because it is it two stop decrease. If you are thinking about it logically, you would naturally assume that if you took and halved your f-stop that you would be letting in half the light. But that is not true because with each f-stop decrease you are halving the amount of light, therefore with two f-stops, you would only have one quarter of the light.

If you take your f-stop scale, and add your half stops, the scale is f/4, f/4.8, and f/5.6. If you then do your third stop range. It would go f/4, f/4.5, f/4.8 (for your half), f/5 and f/5.6.

The key thing to remember about f-stops is that it is a measure of the amount of light that is being let in through your lens. You can think of it as having a paper towel roll, and looking through the roll at the light. If you took a piece of tinfoil and put it over the end of the paper towel roll and poked a pinhole in it, you would have a high f-stop or small aperture opening. The bigger you made the hole, the smaller your f-stop number would become and the more light you would be letting in. Using your aperture control with your shutter control on your camera will give you the proper exposure. The best way to figure out what is happening with the different settings, is just to play with it. Especially if you have a digital camera, you can just delete whatever doesn't turn out well.

Don't worry if you don't know what all the controls on your camera mean. You can learn as little or as much as you want. After all, you can always just set it on auto and your camera will take the picture for you, and chances are it will turn out great. The manual controls are for those shots your camera has a hard time taking, or just for some creative control. Maybe you don't want your shot to look like reality. I post information that you may find helpful in learning how to use your camera. And if it is time for you to buy a new camera, I can help with that too.

Sites Listed by the Author
http://qualitydigitalcameras.net/
http://ratedigitalcameras.net/

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So what exactly is an f-stop? Well, to put it in the very simplest terms, it is the opening that lets light into your camera. And so the numbers on the f-stop relate to the size of the opening that is letting light into your camera.

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noun

is the amount of distance between the nearest and farthest objects that appear in acceptably sharp focus in a photograph. A preferred selection Depth of field ("DOF") in a focused subject in an image can be quite subjective.
-David

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http://www.picturecorrect.com/tips/what-is-an-f-stop/

-Woo Jin

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What is Depth of Field? How aperture, focal length and focus control sharpness

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What is Depth of Field? How aperture, focal length and focus control sharpness

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- Valarie

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Aperture is one of the three pillars of photography (the other two being Shutter Speed and ISO, which are two other chapters in our Photography Basics guide). Of the three, aperture is certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

What is Aperture?

Aperture can be defined as the opening in a lens through which light passes to enter the camera. It is an easy concept to understand if you just think about how your eyes work. As you move between bright and dark environments, the iris in your eyes either expands or shrinks, controlling the size of your pupil.

In photography, the "pupil" of your lens is called aperture. You can shrink or enlarge the size of the aperture to allow more or less light to reach your camera sensor. The image below shows an aperture in a lens:

Aperture can add dimension to your photos by controlling depth of field. At one extreme, aperture gives you a blurred background with a beautiful shallow focus effect. This is very popular for portrait photography.

At the other extreme, it will give you sharp photos from the nearby foreground to the distant horizon. Landscape photographers use this effect a lot.

On top of that, the aperture you choose also alters the exposure of your images by making them brighter or darker.

Aperture Explained in Video

If you prefer to understand how aperture works visually, we put together a video for you that goes through most of the basics. In the video, we go through what aperture is, how it works, and every effect that aperture has in photography. (These points are also covered further down in this article.)

How Aperture Affects Exposure

Aperture has several effects on your photographs. Perhaps the most obvious is the brightness, or exposure, of your images. As aperture changes in size, it alters the overall amount of light that reaches your camera sensor - and therefore the brightness of your image.

A large aperture (a wide opening) will pass a lot of light, resulting in a brighter photograph. A small aperture does just the opposite, making a photo darker. Take a look at the illustration below to see how it affects exposure:

In a dark environment - such as indoors or at night - you will probably want to select a large aperture to capture as much light as possible. This is the same reason why people's pupils dilate when it starts to get dark; pupils are the aperture of our eyes.

How Aperture Affects Depth of Field

The other critical effect of aperture is depth of field. Depth of field is the amount of your photograph that appears sharp from front to back. Some images have a "thin" or "shallow" depth of field, where the background is completely out of focus. Other images have a "large" or "high" depth of field, where both the foreground and background are sharp.

For example, here is an image with a shallow depth of field:

In the image above, you can see that the girl is in focus and appears sharp, while the background is completely out of focus. My choice of aperture played a big role here. I specifically used a large aperture in order to create a shallow focus effect (yes, the larger your aperture, the bigger this effect). This helped me bring the attention of the viewer to the subject, rather than busy background. Had I used a narrower aperture, the subject would not be separated from the background as effectively.

One trick to remember this relationship: a large aperture results in a large amount of both foreground and background blur. This is often desirable for portraits, or general photos of objects where you want to isolate the subject. Sometimes you can frame your subject with foreground objects, which will also look blurred relative to the subject, as shown in the example below:

Quick Note: The appearance of the out-of-focus areas (AKA whether it looks good or not) is often referred to as " bokeh". Bokeh is the property of the lens, and some lenses have better bokeh than others. This article explains how to get better bokeh as a photographer. Even though some lenses are better than others, almost all lenses are capable of a nice shallow focus effect if you use a large aperture and get close enough to your subject.

On the other hand, a small aperture results in a small amount of background blur, which is typically ideal for some types of photography such as landscape and architecture. In the landscape photo below, I used a small aperture to ensure that both my foreground and background were as sharp as possible from front to back:

Here is a quick comparison that shows the difference between using a large vs a small aperture and what it does to your depth of field:

As you can see, in the photograph on the left, only the head of the lizard appears in focus and sharp, while the background and foreground are both transitioning into blur. Meanwhile, the photo on the right has everything from front to back appearing in focus. This is what using large vs small aperture does to photographs.

What Are F-Stop and F-Number?

So far, we have only discussed aperture in general terms like large and small. However, it can also be expressed as a number known as "f-number" or " f-stop ", with the letter "f" appearing before the number, such as f/8.

Most likely, you have noticed aperture written this way on your camera before. On your LCD screen or viewfinder, your aperture will usually look something like this: f/2, f/3.5, f/8, and so on. Some cameras omit the slash and write f-stops like this: f2, f3.5, f8, and so on. For example, the Nikon camera below is set to an aperture of f/8:

So, f-stops are a way of describing the size of the aperture for a particular photo. If you want to find out more about this subject, we have a comprehensive article on f-stop that explains why it's written that way and is worth checking out.

Large vs Small Aperture

There's a catch - one important part of aperture that confuses beginning photographers more than anything else. This is something you really need to pay attention to and get correct: Small numbers represent large apertures, and large numbers represent small apertures!

That's not a typo. For example, f/2.8 is larger than f/4 and much larger than f/11. Most people find this awkward, since it goes against our basic intuition. Nevertheless, this is a fact of photography. Take a look at this chart:

This causes a huge amount of confusion among photographers, because it's completely the reverse of what you would expect at first. However, there is a reasonable and simple explanation that should make it much clearer to you: Aperture is a fraction.

When you are dealing with an f-stop of f/16, for example, you can think of it like the fraction 1/16th. Hopefully, you already know that a fraction like 1/16 is clearly much smaller than the fraction 1/4. For this exact reason, an aperture of f/16 is smaller than f/4. Looking at the front of your camera lens, this is what you'd see:

So, if photographers recommend a large aperture for a particular type of photography, they're telling you to use something like f/1.4, f/2, or f/2.8. And if they suggest a small aperture for one of your photos, they're recommending that you use something like f/8, f/11, or f/16.

How to Pick the Right Aperture

Now that you're familiar with large vs small apertures, how do you know what aperture to use for your photos? Let's revisit two of the most important effects of aperture: exposure and depth of field. First, here is a quick diagram to refresh your memory on how aperture affects the exposure of an image:

If you've read the prior chapter in our Photography Basics guide covering shutter speed, you already know that aperture isn't the only way to change how bright a photo is. Nevertheless, it plays an important role. In the graphic above, if I didn't allow myself to change any other camera settings like shutter speed or ISO, the optimal aperture would be f/5.6.

In a darker environment, where you aren't capturing enough light, the optimal aperture would change. For example, you may want to use a large aperture like f/2.8 at night, just like how our eye's pupils dilate to capture every last bit of light:

As for depth of field, recall that a large aperture value like f/2.8 will result in a large amount of background blur (ideal for shallow focus portraits), while values like f/8, f/11, or f/16 will give you a lot more depth of field (ideal for landscapes and architectural photography).

In fact, depth of field is the part of aperture that I recommend thinking about the most. My process for almost every photo I take goes like this:

Ask myself how much depth of field I want

Set an aperture that achieves it

Set a shutter speed that makes my photo the proper brightness

If that shutter speed leads to unsharp photos thanks to too much motion blur, dial back the shutter speed and raise my ISO instead

Win photo contest :)

Here is a quick chart that lays out everything we've covered so far:

Setting Aperture in Your Camera

If you haven't guessed it already, we highly recommend selecting your aperture manually as a photographer. If you allow the camera to set it automatically, you are likely to end up with the completely wrong depth of field in your image.

There are two modes in photography which allow you to select the aperture manually. These are aperture-priority mode and manual mode. Aperture-priority mode is written as "A" or "Av" on most cameras, while manual is written as "M." Usually, you can find these on the top dial of your camera (read more also in our article on camera modes):

In aperture-priority mode, you select the desired aperture, and the camera automatically selects your shutter speed. You can select ISO manually or automatically. Aperture priority mode is great for everyday photography, where you rarely need to worry about any camera settings other than aperture. It's what I use 95% of the time even for professional landscape and portrait photography.

In manual mode, you select both aperture and shutter speed manually. (ISO can again be manual or auto.) Manual mode takes more time and usually gives you the same results as aperture priority anyway. It's only needed in special situations where you need a consistent exposure from shot to shot, or when the camera's meter is messing up. I use it for Milky Way photography and for portraiture with flash.

Minimum and Maximum Aperture of Lenses

Every lens has a limit on how large or how small the aperture can get. If you take a look at the specifications of your lens, it should say what the maximum and minimum apertures are. For almost everyone, the maximum aperture will be more important, because it tells you how much light the lens can gather at its maximum (basically, how dark of an environment you can take photos - and how much of a shallow focus effect you can achieve).

A lens that has a maximum aperture of f/1.4 or f/1.8 is considered to be a "fast" lens, because it can pass through more light than, for example, a lens with a "slow" maximum aperture of f/4.0. That's why lenses with large apertures usually cost more.

By comparison, the minimum aperture is not that important, because almost all modern lenses can provide at least f/16 at the minimum. You will rarely need anything smaller than that for day-to-day photography.

With some zoom lenses, the maximum aperture will change as you zoom in and out. For example, with the Nikon 18-55mm f/3.5-5.6 AF-P lens, the largest aperture shifts gradually from f/3.5 at the wide end to just f/5.6 at the longer focal lengths. More expensive zooms tend to maintain a constant maximum aperture throughout their zoom range, like the Nikon 24-70mm f/2.8. Prime lenses also tend to have larger maximum apertures than zoom lenses, which is one of their major benefits.

The maximum aperture of a lens is so important that it's included in the name of the lens itself. Sometimes, it will be written with a colon rather than a slash, but it means the same thing (like the Nikon 50mm 1:1.4G below).

Examples of Which Aperture to Use

Now that we have gone through a thorough explanation of how aperture works and how it affects your images, let's take a look at the situations where you'd want to use various f-stops.

f/0.95 - f/1.4 - Such "fast" maximum apertures are only available on premium prime lenses, allowing them to gather as much light as possible. This makes them ideal for any kind of low-light photography (such as photographing the night sky, wedding receptions, portraits in dimly-lit rooms, corporate events, etc). With such wide f-stops, you will get very shallow depth of field at close distances, where the subject will appear separated from the background.

f/1.8 - f/2.0 - Some enthusiast-grade prime lenses are limited to f/1.8, which still has very good low-light capabilities. Also, if your purpose is to yield aesthetically-pleasing images with shallow focus, these lenses be of tremendous value. Shooting between f/1.8 and f/2 typically turns your backgrounds nice and creamy for portraiture and other similar types of photography.

f/2.8 - f/4 - Most zoom lenses are limited to a maximum aperture of f/2.8 to f/4 at best. While they are not as capable as f/1.4 lenses in terms of light-gathering capabilities, they are still enough to shoot in reasonably low light conditions, especially if the lens or camera has image stabilization. You'll get some subject separation at these apertures, but usually not enough to make the background completely fuzzy. Such apertures are great for travel, sports, and wildlife photography.

f/5.6 - f/8 - This is the right starting point for most landscape and architectural photography. It's also ideal for documentary and portrait photography where you don't want a blurry background. Also, most lenses are sharpest around f/5.6, which doesn't matter as much as getting the right depth of field, but is still nice.

f/11 - f/16 - Typically used for photographing scenes where as much depth of field as possible is needed, like macro photography or landscape photography with a nearby foreground. Even though these apertures offer more depth of field, they do lose some low-level sharpness due to the effect of lens diffraction.

f/22 and smaller - Only shoot at such small apertures if you know what you are doing. Sharpness suffers greatly at f/22 and smaller apertures because of diffraction, so you should avoid using them when possible. If you need to get more depth of field, it is usually best to move away from your subject or use a focus stacking technique instead.

You've made it this far, but are you willing to learn more about aperture? So far we have only touched the basics, but aperture does so much more to your photographs. Let's take a closer look.

Everything Aperture Does to Your Photos

Ever wondered how else aperture affects your photographs aside from brightness and depth of field? In this part of the article, we will go through all other ways aperture impacts your images, from sharpness to sunstars, and tell you exactly why each matters.

Before diving into too many specifics, here's a quick list of everything aperture affects in photography:

The brightness / exposure of your photos and depth of field, as discussed so far

Sharpness loss due to diffraction

Sharpness loss due to lens quality

Starburst effects on bright lights

Visibility of camera sensor dust specks

The quality of background highlights (bokeh)

Focus shift on some lenses

Ability to focus in low light (under some conditions)

Controlling the amount of light from the flash

1. The Negative Effect of Diffraction

So, if you're a landscape photographer who wants everything as sharp as possible, you should use your lens's smallest aperture, like f/22 or f/32 to get maximum depth of field, right?

No!

If we go back and take a close look at the photo of the lizard from earlier in this article, where I used apertures of f/4 and f/32, you can see how diffraction is making the second shot less sharp. Here are the images when zoomed in to 100% view:

Here, you're seeing an effect called diffraction. Physics majors will know what I'm talking about, but diffraction is a foreign concept to most people. So, what is it?

Diffraction is actually quite simple. When you use a tiny aperture like f/32, you literally squeeze the light that passes through your lens. It ends up interfering with itself, growing blurrier, and resulting in photos that are noticeably less sharp.

At what aperture does diffraction start to become an issue? It depends upon a number of factors, including the size of your camera sensor and the size of your final print. Personally, on my full-frame camera, I see hints of diffraction at f/8, but it's not enough to bother me. I actually use even smaller apertures like f/11 and f/16 all the time when I have a close foreground in landscape photography. However, I try to avoid f/22 or smaller, since I lose too much detail at that point.

Diffraction isn't necessarily a huge problem, but it exists. Don't be afraid to take pictures at f/11 or f/16 just because you lose a little bit of sharpness. In many cases, the added depth of field is worth the tradeoff.

In macro photography, diffraction can be a bit more of a problem close-focusing actually makes your effective aperture a lot smaller than it really is. Although the math behind that gets a bit complicated, basically, shooting at f/11 at macro distances will show diffraction a lot more compared to if you're shooting a landscape at f/11. In other words, keep an eye out for diffraction when shooting macro.

Side Note

If your camera has a smaller sensor or a very high pixel density, you'll see diffraction sooner. On APS-C sensors (like on Nikon D3x00 series, Nikon D5x00 series, Fuji X-series, Sony A6x00 series, and many others), divide all these numbers by 1.5. On Micro Four-Thirds cameras (like those from Olympus and Panasonic), divide all these numbers by 2. In other words, I don't recommend using f/11 with a micro four-thirds camera, since it's equivalent to f/22 with a full-frame camera.

2. Lens Aberrations

Here's a fun one. For some reason, everyone wants to take sharp photos! One of the ways to do so is to minimize the visibility of lens aberrations. So, what are lens aberrations? Quite simply, they are image quality problems with a photo, caused by your lens.

Although most problems in photography are because of user error - things like missed focus, poor exposure, or a distracting composition - lens aberrations are entirely due to your equipment. They are fundamental, optical problems that you'll notice with any lens if you look too closely, although some lenses are better than others. For example, consider the image below:

What's going on here? In this crop, most of the lights look smeared rather than perfectly round. On top of that, the crop just isn't very sharp. That's lens aberration at work! The lights didn't look this blurry in the real world. My lens added this problem.

It's likely that your lenses are blurrier at certain apertures than others, and it's almost always blurrier in the corner of the image than the center. That's due to lens aberrations.

Aberrations can appear in several different forms. This article would be way too long if I explained every possible aberration in detail: vignetting, spherical aberration, field curvature, coma, distortion, color fringing, and more. Instead, it's more important to know why aberrations occur, including how your aperture setting can reduce them.

It starts with a simple fact: designing lenses is difficult. When the manufacturer fixes one problem, another tends to appear. It's no surprise that modern lens designs are extremely complex.

Unfortunately, even today's lenses aren't perfect. They tend to work fine in the center of an image, but everything gets worse near the edges. That's because lenses are especially difficult to design around the corners.

Here's a diagram that explains what I mean:

And that brings us to aperture.

Many people don't realize a simple fact about aperture: it literally blocks the light transmitted by the edges of your lens. (This doesn't lead to black corners in your photos, because the center regions of a lens can still transmit light to the edges of your camera sensor.)

As your aperture closes, more and more light from the sides of your lens will be blocked, never making it to your camera sensor. Only the light from the center area will pass through and form your photo! As the diagram above shows, this central area is far easier for camera manufacturers to design. The end result is that your photos will have fewer aberrations at smaller and smaller apertures.

How does this look in practice? See the photos below (heavy crops from the top-left corner):

What you're seeing above may look like an increase in sharpness, but it's really a decrease in aberrations. The end result? At f/5.6 on this particular lens, my photo is much sharper than at f/1.4.

Here's a key question: How does this balance out with diffraction, which harms sharpness increasingly more as your aperture gets narrower and narrower?

In practice, the answer is that most lenses end up sharpest around f/4, f/5.6, or f/8. Those "medium" apertures are small enough to block light from the edges of a lens, but they aren't so small that diffraction is a significant problem. However, you'll want to test this on your own equipment.

Of course, you can still take good photos at large apertures like f/1.4 or f/2. As I mentioned earlier, portrait photographers sometimes pay thousands of dollars to get a lens exactly for that purpose! So, don't lock your lens to f/5.6 just because it gives you a tad more corner sharpness up close. It's better to choose an aperture that gives you the right artistic look to the image.

Side Note

Some types of aberrations don't change much as you stop down, or they may even get slightly worse. Axial chromatic aberration, for example - color fringes near the edges of your frame - often work that way. This is normal. It happens because a small aperture doesn't inherently reduce aberrations; it simply blocks light that has passed through the edges of your lens. So, naturally, if the edges aren't the source of your problem, you won't see an improvement by stopping down.

3. Starburst and Sunstar Effects

Starbursts, also called sunstars, are beautiful elements that you'll find in certain photographs. Despite the odd names - one a type of candy; the other a type of starfish - I always try to capture them in my landscape photos. Here's an example:

How does this work? Essentially, for every aperture blade in your lens, you'll end up with a sunbeam. This only happens if you photograph a small, bright point of light, such as the sun when it is partly blocked. This is fairly common in landscape photography. If you want the strongest possible starburst, use a small aperture. Whenever the sun is in my photo, I almost always set f/16 purely to capture this effect.

Also, the starburst effect looks different from lens to lens. It all depends upon your aperture blades. If your lens has six aperture blades, you'll get six sunbeams. If your lens has eight aperture blades, you'll get eight sunbeams. And, if your lens has nine aperture blades, you'll get eighteen sunbeams.

Wait, what?

That's no typo. You always end up with an even number of sunbeams. If your lens has an odd number of aperture blades, you'll get double the number of sunbeams.

It sounds strange, but the reason is actually quite simple. In lenses with an even number of aperture blades (and a fully symmetrical design), half of the sunbeams will overlap the other half. So, you don't see all of them in your final photo.

Here's a diagram to show what I mean:

Most Nikon lenses have seven or nine aperture blades, resulting in 14 and 18 sunbeams respectively. Most Canon lenses have eight aperture blades, resulting in eight sunbeams. I took the photo above using the Nikon 20mm f/1.8G lens, which has 7 aperture blades. That's why the image has 14 sunbeams.

It's not just the number of blades that matters, though - their shape is also important. Some aperture blades are rounded (which results in a more pleasant out-of-focus background blur), and others are straight. If your goal is to capture good starbursts, straight aperture blades typically produce more defined rays of light.

Again, some lenses are better than others in this regard. For the best results, find a lens that's known to have good starbursts, and then set it to a small aperture like f/16. That's going to give you the strongest definition in your starbursts.

Finally, there's one last related effect that I wanted to mention briefly. When you shoot into the sun, you might end up with flare in your photographs, as shown below. Depending upon your chosen aperture, the size and shape of this lens flare may change slightly. This isn't a big deal, but it still exists.

4. Small Aperture and Unwanted Elements

When you shoot through things such as fences, dirty windows, plants, and even water droplets on your lens, you'll probably be disappointed by photos taken with a small aperture.

Small apertures like f/11 and f/16 give you such a large depth of field that you may accidentally include elements that you don't want to be in focus! For example, if you're shooting at a waterfall or by the ocean, an aperture of f/16 could render a tiny water droplet on your lens into a distinct, ugly blob:

In cases like that, it's better just to use a wider aperture - something like f/5.6, perhaps - in order to capture the water droplet so out-of-focus that it doesn't even appear in your image. In this particular case, you could simply wipe the droplet off, but that's not possible if you're shooting through something like a dirty window.

Side Note

You might have realized that this section is really just an extension of depth of field, and that's true! However, it's a bit of a special case, so I decided to mention it specifically.

Another example of shooting through things is when a piece of dust lands on your camera sensor. Unfortunately, as you change lenses, this is very common. Dust specks on your camera sensor will show up very clearly at small apertures like f/16, even if they're invisible at something larger, like f/4.

Luckily, they are very easy to remove in post-production software like Photoshop or Lightroom, though it can be annoying if you have to remove dozens of them from a single photo. That's why you should always keep your camera sensor clean.

5. Changes to Your Bokeh

What is bokeh? It's simply the quality of your background blur. If you take a lot of portraits, macro photos, or wildlife photos, you'll end up with out-of-focus backgrounds in most of your images. Naturally, you want them to look as good as possible! Different aperture settings will change the shape of your background blur.

Why is that? It's because the background blur of your photographs always takes on the shape of your aperture blades. So, if your aperture blades are shaped like a heart, you'll end up with heart-shaped background blur. Most of the time, that would qualify as distracting bokeh, although it's kind of cute in this photo of two fake tortoises:

On some lenses, aperture blades change shape a bit as they open and close. Large aperture settings (such as f/1.8) often have rounder background blur compared to smaller aperture settings. You'll also get more background blur at large apertures, since your depth of field is thinner.

If bokeh is something that matters to you, you'll want to test this on your particular lenses. Take some out-of-focus photos of a busy scene, each using a different aperture setting, and see which one looks the best. Most of the time, it will be the lens's widest aperture, but not always.

6. Focus Shift Issues

With certain lenses - even if you're in manual focus, and you don't move your focus ring - your point of focus may shift as you use smaller and smaller apertures.

Obviously, this isn't ideal. How do you tell if your lens has problematic focus shift? It's pretty easy. Here are the steps:

Put your camera on a tripod, and set your lens to manual focus.

Find an object with small details that extends backwards, and focus at the center of it. A table with a tablecloth works well.

Double check: When take a test photo and magnify it, you should see pixel-level details, as well as portions of the photo that are clearly out of focus.

Take a photo at your lens's widest aperture, and then at progressively smaller apertures. Be sure not to move your focus ring, and double check that you are using manual focus.

On your computer, zoom into 100% on these photos and see if the sharpest point of focus moves continuously farther back as you stop down. The more it moves, the worse your focus shift issue is.

You're done!

If your lens has extreme levels of focus shift, you'll want to compensate for it:

With your widest aperture, just focus like normal.

As you stop down the aperture, make sure to set your aperture first, then focus second (rather than focusing first). On DSLRs, we recommend focusing in live view at these apertures, because the viewfinder always focuses at the widest aperture. Mirrorless camera users don't need to worry about that.

With small apertures like f/8 and beyond, your depth of field will be large enough to hide any focus shift problems, so just focus like normal.

Side Note

When it comes down to it, focus shift is just another type of lens aberration. The edges of your lens may not focus light the same as the center, so, by stopping down - again, blocking light from the edges - your focus point changes slightly. That's the underlying reason for this effect.

7. Ease of Focusing

The autofocus system on your camera doesn't work well unless it receives plenty of light.

So, if you're shooting with a cheaper lens like a 70-300mm f/4.5-5.6, the largest aperture isn't bright enough to gather a lot of light. Focusing in dark conditions may be impacted. This is part of why a lot of pro photographers will use a more expensive lens like a 70-200mm f/2.8 instead.

You'll also enjoy a brighter viewfinder (on a DSLR) or a less noisy viewfinder (on a mirrorless camera) if your lens has a large maximum aperture. If you shoot a lot in low light, this can make it much easier to focus and compose your images.

8. Flash Exposure

When using speedlights or any kind of strobes, it is important to remember that aperture takes on a whole different role of controlling flash exposure. While shutter speed's role becomes controlling ambient light, aperture has an outsized impact on how much light from your flash is captured. Even though it's just a subset of exposure, we wanted to include it in this section, since flash is tightly correlated to lens aperture.

A Chart of Everything Aperture Does

Once you understand the information above, you will know everything aperture does to your photos. However, it may take a few re-reads of this article before it's all completely clear.

Practice is your best friend. Go outside, take some photos, and get a feel for aperture yourself.

If it helps, I compiled the main information in this article into a chart. This chart covers the most important effects of aperture in photography, as well as common terms that photographers use to describe their settings.

Note that to make this diagram easier to see, I did not darken or lighten any of the sample illustrations (as would occur in the real world). Instead, I simply wrote "brightest" through "darkest":

Although this chart is intentionally simplified, it covers all the basics that you need to know. Feel free to download and print this chart if you find it useful. Just right-click on the image, then select "save as," and pick the location where you want to store it.

Aperture FAQ

We put together some of the most frequently-asked questions related to aperture below.
How Does Aperture Affect Bokeh?
Bokeh refers to the quality of out-of-focus highlights of the image rendered by the camera lens. Using the maximum aperture of the lens will typically yield circular background highlights of large size, whereas stopping down the lens will typically result in highlights looking smaller and taking different shapes such as heptagon. These shapes depend on the number of aperture blades and their roundness. Here is an image of a 50mm f/1.4 prime lens stopped down to f/2.8 and f/4 apertures:

How Does Aperture Affect Sharpness?
Aperture is clearly a crucial setting in photography and it is possibly the single most important setting of all. Aperture affects several different parts of your photo, but you'll get the hang of everything fairly quickly. For a quick summary, a narrow aperture...

Makes your photos darker

Gives you more depth of field

Increases blur from diffraction

Decreases blur from most lens aberrations

Makes sensor dust more visible

Heightens the intensity of starbursts

...whereas a wide aperture does the opposite.

Soon, this won't be something that you even need to think about; you'll remember it all naturally. Personally, if I want a starburst effect in my photos, I immediately know to use an aperture of f/16. When I need as much light as possible, I set a larger aperture like f/2.8 or f/2 without a second thought. It doesn't take too much practice to get to that point.

With how important aperture is, it shouldn't be a surprise that, at Photography Life, we shoot in aperture-priority or manual mode all of the time. We simply never want the camera to select the aperture for us. It's just too important, and it is one of those basic settings that every beginner or advanced photographer needs to know in order to take the best possible images.

As always, it's best if you learn all this for yourself. Find something spectacular to capture, and put your new knowledge into practice. The more photos you take, the more you'll learn. Aperture is no exception.

Below are some other related posts you might enjoy:

Hopefully, you found that this article explains the basics of aperture in a way that is understandable and straightforward.

If you are ready to move on, the next important camera setting to learn is ISO, which we explain in Chapter 5 of our Photography Basics guide.

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What is Aperture? Understanding Aperture in Photography

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Aperture is one of the three pillars of photography, and certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

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Explanation of Depth of field

-Thomas

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Basics

When a lens focuses on a subject at a distance, all subjects at that distance are sharply focused. Subjects that are not at the same distance are out of focus and theoretically are not sharp. However, since human eyes cannot distinguish very small degree of unsharpness, some subjects that are in front of and behind the sharply focused subjects can still appear sharp. The zone of acceptable sharpness is referred to as the depth of field. Thus, increasing the depth of field increases the sharpness of an image. We can use smaller apertures for increasing the depth of field.

The following shows an example. The lens focuses at the middle between the 3 inch and 4 inch marks. Thus, the 3 inch and 4 inch marks are sharp in all images. The 5 inch mark is not very sharp at F3.2, and is improved as the lens closes down to F3.6. Then, it becomes sharp in all subsequent images. The 6 inch and 7 inch marks are not sharp until F5.0 and F6.4, respectively. The 8 inch mark becomes reasonably sharp when the lens closes down to F8.0. The 9 inch and 10 inch marks are not sharp in all images; but, they become sharper as the lens closes down. For the foreground, the 2 inch mark is acceptable at F3.2 and becomes "focused" at F4.0. The 1 inch mark is not sharp until F5.6, and the lead of the ruler becomes reasonably sharp at F7.1. As you can see, the range of sharpness ( i.e., depth of field) gets larger as the aperture gets smaller. Therefore, use a smaller aperture if a greater depth of field is needed. Please check theAperture-Priority Mode to know more about the use of aperture and its impact on depth of field.

F3.2

F3.6

F4.0

F4.5

F5.0

F5.6

F6.4

F7.1

F8.0

F9.0

Click on the image to see a larger one

Why?

Suppose the lens focuses on the yellow dot as shown in the figure below. This subject generates a yellow dot on the image plane. Once focused, all subjects that have the same subject-lens distance as that of the yellow dot will appear sharp. Now, consider a white dot that is behind the yellow dot ( i.e., with larger subject-lens distance). Since it is out of focus, it will not produce a sharp white dot image. Instead, its image is formed somewhere in front of the image plane. On the image plane, the image of this white dot is a circle as shown below. This circle is usually referred to as acircle of confusion. As the subject-lens distance increases, the size of this circle increases. The same holds true for a subject in front of the yellow dot ( e.g., the green dot in the following figure). Since these circles of confusion are actually out of focus images of subjects, if we can reduce the size of circle of confusion, we can increase the sharpness of the resulting image. But, how?

It turns out to be very simple. Since circles of confusion are formed by light rays passing through the lens tube, the size of a circle of confusion is proportional to the amount of light that can pass through the lens tube. This means smaller ( resp., larger) circles of confusion will be formed if less ( resp., more) light can pass through. Restricting how much light can pass through the lens is the function of the diaphragm in the lens tube that sets the aperture values. Therefore, a smaller aperture means a smaller diaphragm opening, which, in turn, means allowing less light to strike the film/CCD plane. Thus, we have smaller circles of confusion and, as a result, a sharper image!

Hyperfocal Distance

In addition to closing down the diaphragm ( i.e., smaller aperture), we can also focus at thehyperfocal distance. If a lens focuses at infinity, the depth of field starts at somewhere in front of the lens and extends to infinity. More precisely, from that point on, the scene appears sharp, and subjects between that point and the lens are out of focus. The distance from the lens to that point is referred to as thehyperfocal distance. In the figure below, the hyperfocal distance is marked with a thick red line.

After determining the hyperfocal distance, we can point the camera at this distance. The resulting depth of field starts from halfway of the hyperfocal distance and extends to infinity. This is, in fact, the maximum depth of field we can get. The concept is shown in the figure below.

Why is this hyperfocal distance important? When shooting a distant subject or scene, many people point the camera to that subject(s). The result may be satisfactory; however, in many cases the foreground looks out of focus. This is, of course, because of insufficient depth of field. Should this happen, the above technique becomes very useful: (1) focus at infinity;(2) determine the hyperfocal distance;(3) refocus at the hyperfocal distance; and(4) take a photo.

Please note that hyperfocal distance is a function of the aperture being used. More precisely, changing aperture changes hyperfocal distance.

Can We Use the Smallest Aperture to Yield Greater Depth of Field?

Unfortunately, the answer is "no." As the light rays passing the lens tube and the diaphragm, some may be diffracted as shown in the figures below. If the diaphragm is large ( i.e., a large aperture), because the proportion of the diffracted light and the non-diffracted light is so small and is negligible, diffraction does not contribute to the loss-of-quality very much. See the left figure below. However, when the diaphragm is small ( i.e., a small aperture), the amount of light that can pass through the diaphragm is reduced and hence the proportion of the diffracted and non-diffracted light becomes significant. As a result, the quality of the image is also reduced. See the right figure below. Therefore, closing the diaphragm ( i.e., using small apertures) all the way down to the smallest aperture may not increase the quality of an image. In general, the quality of a lens increases as diaphragm closes down. This improvement will reach certain point. After this, quality goes down because of the impact of diffraction.

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When a lens focuses on a subject at a distance, all subjects at that distance are sharply focused. Subjects that are not at the same distance are out of focus and theoretically are not sharp. However, since human eyes cannot distinguish very small degree of unsharpness, some subjects that are in front of and behind the sharply focused subjects can still appear sharp.

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-Shwun

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Photography deals with capturing light in a way that appeals to your artistic sensibilities, whether you prefer perfectly-lit, tack-sharp portraits worthy of presidential candidates or blurrier, artistic renderings of NASCAR competitors roaring by at 180 mph (290 kph). To consistently create the kinds of pictures that will make your creative spirit soar, you need a firm grasp of common camera settings such as shutter speed, ISO setting and f-stop (or focal stop).

F-stops in particular have a tremendous effect on image characteristics, some of which may not be obvious to amateur shooters. For the bulk of this article, we'll discuss and improve your grasp of the mysterious f-stop.

S hutter speed and ISO settings are also important concepts that will help you flesh out your understanding of how cameras work. For more information on these subjects, check out our articles " What is ISO speed?" and " 10 Important Photography Terms."

When you take pictures, you're using the interplay between shutter speed, ISO and f-stop settings to control exposure. F-stops especially seem to baffle many novice shooters, perhaps because of the weird alphanumeric symbols used to indicate these settings. Happily, figuring out f-stops is really pretty simple once you disassemble the term and break it up into understandable parts.

For starters, your camera has a mechanical aperture that controls how much light enters the camera. This aperture can change in size, and it works a lot like the pupil in your eye. In general, the brighter the scene, the more the pupil constricts; in low light, the pupil is larger, letting in as much light as possible. The same goes for your camera's aperture in most situations.

The f-stop number is determined by the focal length

of the lens divided by the diameter of the aperture. Focal length refers to a lens' field of view (sometimes called angle of view), which is the width and height of the area that a particular lens can capture. Focal length is often printed right on the camera lens.

A lens with a 100mm focal length set to an f-stop of f/10 has an aperture diameter of 10mm. Keep in mind that doubling the f-stop number halves the size of the aperture opening. So, moving from f/10 to f/20 decreases the size of the aperture from 10mm to 5mm. If you use an SLR (single-lens reflex) camera that lets you affix a range of lenses, the f-stop numbers will be different for each lens.

All technical details aside, you won't need to spend a lot of time sweating the finer points of f-stops. What you really need to know is how to adjust the aperture diameter to your advantage as you shoot. Keep reading to find out how aperture control affects the way your pictures look.

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Photography deals with capturing light in a way that appeals to your artistic sensibilities, whether you prefer perfectly-lit, tack-sharp portraits worthy of presidential candidates or blurrier, artistic renderings of NASCAR competitors roaring by at 180 mph (290 kph).

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http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

myat kaung khant

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-Oscar

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Aperture Foundation: Publisher and Center for the Photo Community

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Aperture, a not-for-profit foundation, connects the photo community with the most inspiring work, the sharpest ideas, and with each other-in print, in person, and online.

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ap·er·ture

ˈapərˌCHər,ˈapərˌCHo͝or/

a space through which light passes in an optical or photographic instrument, especially the variable opening by which light enters a camera. -David

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A guide to aperture - Thomas

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Understand what is Aperture in photographic basic

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Shutter speed, apertures and depth of field, three most important elements in photography. I have been through the early days of confusion, hope this will help. Photography in Malaysia: Malaysians photographers' online portfolios, Resourceful photographic tips & tricks

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Over the last couple of weeks I've been writing a series of posts on elements that digital photographers need to learn about in order to get out of Auto mode and learn how to manually set the exposure of their shots. I've largely focussed upon three elements of the ' exposure triangle' - ISO, Shutter Speed and . I've previously written about the first two and today would like to turn our attention to Aperture.

Before I start with the explanations let me say this. If you can master aperture you put into your grasp real creative control over your camera. In my opinion - aperture is where a lot of the magic happens in photography and as we'll see below, changes in it can mean the difference between one dimensional and multi dimensional shots.

What is Aperture?

Put most simply - Aperture is 'the opening in the lens.'

When you hit the shutter release button of your camera a hole opens up that allows your cameras image sensor to catch a glimpse of the scene you're wanting to capture. The aperture that you set impacts the size of that hole. The larger the hole the more light that gets in - the smaller the hole the less light.

Aperture is measured in 'f-stops'.

You'll often see them referred to here at Digital Photography School as f/number - for example f/2.8, f/4, f/5.6,f/8,f/22 etc. Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens (and the amount of light getting through). Keep in mind that a change in shutter speed from one stop to the next doubles or halves the amount of light that gets in also - this means if you increase one and decrease the other you let the same amount of light in - very handy to keep in mind).

One thing that causes a lot of new photographers confusion is that large apertures (where lots of light gets through) are given f/stop smaller numbers and smaller apertures (where less light gets through) have larger f-stop numbers. So f/2.8 is in fact a much larger aperture than f/22. It seems the wrong way around when you first hear it but you'll get the hang of it.

Depth of Field and Aperture

There are a number of results of changing the aperture of your shots that you'll want to keep in mind as you consider your setting but the most noticeable one will be the depth of field that your shot will have.

Depth of Field (DOF) is that amount of your shot that will be in focus. Large depth of field means that most of your image will be in focus whether it's close to your camera or far away. For example the landscape shot above has an aperture of f/16 and the result is that both the mountain in the background and the boats in the foreground remain in focus.

Small (or shallow) depth of field means that only part of the image will be in focus and the rest will be fuzzy (like in the portrait at the top of this post. You'll see in it that the subjects eyes are in focus but the background is blurred. Even her hair which is only a little behind her eyes is blurred. This is a very shallow depth of field and was taken with an aperture of f1.8).

Similarly this creative birth announcement image was shot at f1.8 and again you see the shallow depth of field with the ultrasound in focus but everything else blurred.

Here's one more example with an even wider aperture of f1.2 that leaves the guitar in focus but everything else blurred.

Aperture has a big impact upon depth of field. Large aperture (remember it's a smaller number) will decrease depth of field while small aperture (larger numbers) will give you larger depth of field.

It can be a little confusing at first but the way I remember it is that small numbers mean small DOF and large numbers mean large DOF.

Let me illustrate this with two pictures I took earlier this week in my garden of two flowers.

The first picture on the left was taken with an aperture of f/22 and the second one was taken with an aperture of f/2.8. The difference is quite obvious. The f/22 picture has both the flower and the bud in focus and you're able to make out the shape of the fence and leaves in the background.

The f/2.8 shot on the right has the left flower in focus (or parts of it) but the depth of field is very shallow and the background is thrown out of focus and the bud to the right of the flower is also less in focus due to it being slightly further away from the camera when the shot was taken.

The best way to get your head around aperture is to get your camera out and do some experimenting. Go outside and find a spot where you've got items close to you as well as far away and take a series of shots with different aperture settings from the smallest setting to the largest. You'll quickly see the impact that it can have and the usefulness of being able to control aperture.

Some styles of photography require large depths of field (and small Apertures)

For example in most landscape photography you'll see small aperture settings (large numbers) selected by photographers. This ensures that from the foreground to the horizon is relatively in focus.

On the other hand in portrait photography it can be very handy to have your subject perfectly in focus but to have a nice blurry background in order to ensure that your subject is the main focal point and that other elements in the shot are not distracting. In this case you'd choose a large aperture (small number) to ensure a shallow depth of field.

Macro photographers tend to be big users of large apertures to ensure that the element of their subject that they are focusing in on totally captures the attention of the viewer of their images while the rest of the image is completely thrown out of focus.

I hope that you found this introduction to Aperture in Digital Photography helpful. Be sure to also check out our introduction to Shutter Speed and introduction to ISO.

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Introduction to Aperture in Photography - dPS

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Over the last couple of weeks I've been writing a series of posts on elements that digital photographers need to learn about in order to get out of Auto mode and learn how to manually set the exposure of their shots. I've largely focussed upon three elements of the ' exposure triangle' - ISO, Shutter Speed and .

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http://www.mir.com.my/rb/photography/fototech/htmls/depth.html

- Su

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Depth of field is the amount of distance between the nearest and farthest objects that appear in acceptably sharp focus in a photograph. A preferred selection Depth of field ("DOF") in a focused subject in an image can be quite subjective. Remember this, adequate selection of DOF for one situation, application may be unacceptable for another photographer.

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http://www.exposureguide.com/focusing-basics.htm
-Snow

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Learn more about aperature with pictures

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Learn more about aperature with pictures

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-Sophie

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http://digital-photography-school.com/understanding-depth-field-beginners/

-Woo Jin

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				A Tedious Explanation of the f/stop
			
		
		
			by Matthew Cole

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				A Tedious Explanation of the f/stop
			
		
		
			by Matthew Cole

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http://www.uscoles.com/fstop.htm
myat kaung khant

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http://digital-photography-school.com/aperture/
-Snow

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http://www.digitalcameraworld.com/2013/07/17/what-is-depth-of-field-how-aperture-focal-length-and-focus-control-whats-sharp/

-Willie

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Aperture, Depth of Field, F Stop All in One

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Aperture, Depth of Field, F Stop All in One

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-Yauk

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Aperture is one of the three pillars of photography (the other two being Shutter Speed and ISO, which are two other chapters in our Photography Basics guide). Of the three, aperture is certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

What is Aperture?

Aperture can be defined as the opening in a lens through which light passes to enter the camera. It is an easy concept to understand if you just think about how your eyes work. As you move between bright and dark environments, the iris in your eyes either expands or shrinks, controlling the size of your pupil.

In photography, the "pupil" of your lens is called aperture. You can shrink or enlarge the size of the aperture to allow more or less light to reach your camera sensor. The image below shows an aperture in a lens:

Aperture can add dimension to your photos by controlling depth of field. At one extreme, aperture gives you a blurred background with a beautiful shallow focus effect. This is very popular for portrait photography.

At the other extreme, it will give you sharp photos from the nearby foreground to the distant horizon. Landscape photographers use this effect a lot.

On top of that, the aperture you choose also alters the exposure of your images by making them brighter or darker.

Aperture Explained in Video

If you prefer to understand how aperture works visually, we put together a video for you that goes through most of the basics. In the video, we go through what aperture is, how it works, and every effect that aperture has in photography. (These points are also covered further down in this article.)

How Aperture Affects Exposure

Aperture has several effects on your photographs. Perhaps the most obvious is the brightness, or exposure, of your images. As aperture changes in size, it alters the overall amount of light that reaches your camera sensor - and therefore the brightness of your image.

A large aperture (a wide opening) will pass a lot of light, resulting in a brighter photograph. A small aperture does just the opposite, making a photo darker. Take a look at the illustration below to see how it affects exposure:

In a dark environment - such as indoors or at night - you will probably want to select a large aperture to capture as much light as possible. This is the same reason why people's pupils dilate when it starts to get dark; pupils are the aperture of our eyes.

How Aperture Affects Depth of Field

The other critical effect of aperture is depth of field. Depth of field is the amount of your photograph that appears sharp from front to back. Some images have a "thin" or "shallow" depth of field, where the background is completely out of focus. Other images have a "large" or "high" depth of field, where both the foreground and background are sharp.

For example, here is an image with a shallow depth of field:

In the image above, you can see that the girl is in focus and appears sharp, while the background is completely out of focus. My choice of aperture played a big role here. I specifically used a large aperture in order to create a shallow focus effect (yes, the larger your aperture, the bigger this effect). This helped me bring the attention of the viewer to the subject, rather than busy background. Had I used a narrower aperture, the subject would not be separated from the background as effectively.

One trick to remember this relationship: a large aperture results in a large amount of both foreground and background blur. This is often desirable for portraits, or general photos of objects where you want to isolate the subject. Sometimes you can frame your subject with foreground objects, which will also look blurred relative to the subject, as shown in the example below:

Quick Note: The appearance of the out-of-focus areas (AKA whether it looks good or not) is often referred to as " bokeh". Bokeh is the property of the lens, and some lenses have better bokeh than others. This article explains how to get better bokeh as a photographer. Even though some lenses are better than others, almost all lenses are capable of a nice shallow focus effect if you use a large aperture and get close enough to your subject.

On the other hand, a small aperture results in a small amount of background blur, which is typically ideal for some types of photography such as landscape and architecture. In the landscape photo below, I used a small aperture to ensure that both my foreground and background were as sharp as possible from front to back:

Here is a quick comparison that shows the difference between using a large vs a small aperture and what it does to your depth of field:

As you can see, in the photograph on the left, only the head of the lizard appears in focus and sharp, while the background and foreground are both transitioning into blur. Meanwhile, the photo on the right has everything from front to back appearing in focus. This is what using large vs small aperture does to photographs.

What Are F-Stop and F-Number?

So far, we have only discussed aperture in general terms like large and small. However, it can also be expressed as a number known as "f-number" or " f-stop ", with the letter "f" appearing before the number, such as f/8.

Most likely, you have noticed aperture written this way on your camera before. On your LCD screen or viewfinder, your aperture will usually look something like this: f/2, f/3.5, f/8, and so on. Some cameras omit the slash and write f-stops like this: f2, f3.5, f8, and so on. For example, the Nikon camera below is set to an aperture of f/8:

So, f-stops are a way of describing the size of the aperture for a particular photo. If you want to find out more about this subject, we have a comprehensive article on f-stop that explains why it's written that way and is worth checking out.

Large vs Small Aperture

There's a catch - one important part of aperture that confuses beginning photographers more than anything else. This is something you really need to pay attention to and get correct: Small numbers represent large apertures, and large numbers represent small apertures!

That's not a typo. For example, f/2.8 is larger than f/4 and much larger than f/11. Most people find this awkward, since it goes against our basic intuition. Nevertheless, this is a fact of photography. Take a look at this chart:

This causes a huge amount of confusion among photographers, because it's completely the reverse of what you would expect at first. However, there is a reasonable and simple explanation that should make it much clearer to you: Aperture is a fraction.

When you are dealing with an f-stop of f/16, for example, you can think of it like the fraction 1/16th. Hopefully, you already know that a fraction like 1/16 is clearly much smaller than the fraction 1/4. For this exact reason, an aperture of f/16 is smaller than f/4. Looking at the front of your camera lens, this is what you'd see:

So, if photographers recommend a large aperture for a particular type of photography, they're telling you to use something like f/1.4, f/2, or f/2.8. And if they suggest a small aperture for one of your photos, they're recommending that you use something like f/8, f/11, or f/16.

How to Pick the Right Aperture

Now that you're familiar with large vs small apertures, how do you know what aperture to use for your photos? Let's revisit two of the most important effects of aperture: exposure and depth of field. First, here is a quick diagram to refresh your memory on how aperture affects the exposure of an image:

If you've read the prior chapter in our Photography Basics guide covering shutter speed, you already know that aperture isn't the only way to change how bright a photo is. Nevertheless, it plays an important role. In the graphic above, if I didn't allow myself to change any other camera settings like shutter speed or ISO, the optimal aperture would be f/5.6.

In a darker environment, where you aren't capturing enough light, the optimal aperture would change. For example, you may want to use a large aperture like f/2.8 at night, just like how our eye's pupils dilate to capture every last bit of light:

As for depth of field, recall that a large aperture value like f/2.8 will result in a large amount of background blur (ideal for shallow focus portraits), while values like f/8, f/11, or f/16 will give you a lot more depth of field (ideal for landscapes and architectural photography).

In fact, depth of field is the part of aperture that I recommend thinking about the most. My process for almost every photo I take goes like this:

Ask myself how much depth of field I want

Set an aperture that achieves it

Set a shutter speed that makes my photo the proper brightness

If that shutter speed leads to unsharp photos thanks to too much motion blur, dial back the shutter speed and raise my ISO instead

Win photo contest :)

Here is a quick chart that lays out everything we've covered so far:

Setting Aperture in Your Camera

If you haven't guessed it already, we highly recommend selecting your aperture manually as a photographer. If you allow the camera to set it automatically, you are likely to end up with the completely wrong depth of field in your image.

There are two modes in photography which allow you to select the aperture manually. These are aperture-priority mode and manual mode. Aperture-priority mode is written as "A" or "Av" on most cameras, while manual is written as "M." Usually, you can find these on the top dial of your camera (read more also in our article on camera modes):

In aperture-priority mode, you select the desired aperture, and the camera automatically selects your shutter speed. You can select ISO manually or automatically. Aperture priority mode is great for everyday photography, where you rarely need to worry about any camera settings other than aperture. It's what I use 95% of the time even for professional landscape and portrait photography.

In manual mode, you select both aperture and shutter speed manually. (ISO can again be manual or auto.) Manual mode takes more time and usually gives you the same results as aperture priority anyway. It's only needed in special situations where you need a consistent exposure from shot to shot, or when the camera's meter is messing up. I use it for Milky Way photography and for portraiture with flash.

Minimum and Maximum Aperture of Lenses

Every lens has a limit on how large or how small the aperture can get. If you take a look at the specifications of your lens, it should say what the maximum and minimum apertures are. For almost everyone, the maximum aperture will be more important, because it tells you how much light the lens can gather at its maximum (basically, how dark of an environment you can take photos - and how much of a shallow focus effect you can achieve).

A lens that has a maximum aperture of f/1.4 or f/1.8 is considered to be a "fast" lens, because it can pass through more light than, for example, a lens with a "slow" maximum aperture of f/4.0. That's why lenses with large apertures usually cost more.

By comparison, the minimum aperture is not that important, because almost all modern lenses can provide at least f/16 at the minimum. You will rarely need anything smaller than that for day-to-day photography.

With some zoom lenses, the maximum aperture will change as you zoom in and out. For example, with the Nikon 18-55mm f/3.5-5.6 AF-P lens, the largest aperture shifts gradually from f/3.5 at the wide end to just f/5.6 at the longer focal lengths. More expensive zooms tend to maintain a constant maximum aperture throughout their zoom range, like the Nikon 24-70mm f/2.8. Prime lenses also tend to have larger maximum apertures than zoom lenses, which is one of their major benefits.

The maximum aperture of a lens is so important that it's included in the name of the lens itself. Sometimes, it will be written with a colon rather than a slash, but it means the same thing (like the Nikon 50mm 1:1.4G below).

Examples of Which Aperture to Use

Now that we have gone through a thorough explanation of how aperture works and how it affects your images, let's take a look at the situations where you'd want to use various f-stops.

f/0.95 - f/1.4 - Such "fast" maximum apertures are only available on premium prime lenses, allowing them to gather as much light as possible. This makes them ideal for any kind of low-light photography (such as photographing the night sky, wedding receptions, portraits in dimly-lit rooms, corporate events, etc). With such wide f-stops, you will get very shallow depth of field at close distances, where the subject will appear separated from the background.

f/1.8 - f/2.0 - Some enthusiast-grade prime lenses are limited to f/1.8, which still has very good low-light capabilities. Also, if your purpose is to yield aesthetically-pleasing images with shallow focus, these lenses be of tremendous value. Shooting between f/1.8 and f/2 typically turns your backgrounds nice and creamy for portraiture and other similar types of photography.

f/2.8 - f/4 - Most zoom lenses are limited to a maximum aperture of f/2.8 to f/4 at best. While they are not as capable as f/1.4 lenses in terms of light-gathering capabilities, they are still enough to shoot in reasonably low light conditions, especially if the lens or camera has image stabilization. You'll get some subject separation at these apertures, but usually not enough to make the background completely fuzzy. Such apertures are great for travel, sports, and wildlife photography.

f/5.6 - f/8 - This is the right starting point for most landscape and architectural photography. It's also ideal for documentary and portrait photography where you don't want a blurry background. Also, most lenses are sharpest around f/5.6, which doesn't matter as much as getting the right depth of field, but is still nice.

f/11 - f/16 - Typically used for photographing scenes where as much depth of field as possible is needed, like macro photography or landscape photography with a nearby foreground. Even though these apertures offer more depth of field, they do lose some low-level sharpness due to the effect of lens diffraction.

f/22 and smaller - Only shoot at such small apertures if you know what you are doing. Sharpness suffers greatly at f/22 and smaller apertures because of diffraction, so you should avoid using them when possible. If you need to get more depth of field, it is usually best to move away from your subject or use a focus stacking technique instead.

You've made it this far, but are you willing to learn more about aperture? So far we have only touched the basics, but aperture does so much more to your photographs. Let's take a closer look.

Everything Aperture Does to Your Photos

Ever wondered how else aperture affects your photographs aside from brightness and depth of field? In this part of the article, we will go through all other ways aperture impacts your images, from sharpness to sunstars, and tell you exactly why each matters.

Before diving into too many specifics, here's a quick list of everything aperture affects in photography:

The brightness / exposure of your photos and depth of field, as discussed so far

Sharpness loss due to diffraction

Sharpness loss due to lens quality

Starburst effects on bright lights

Visibility of camera sensor dust specks

The quality of background highlights (bokeh)

Focus shift on some lenses

Ability to focus in low light (under some conditions)

Controlling the amount of light from the flash

1. The Negative Effect of Diffraction

So, if you're a landscape photographer who wants everything as sharp as possible, you should use your lens's smallest aperture, like f/22 or f/32 to get maximum depth of field, right?

No!

If we go back and take a close look at the photo of the lizard from earlier in this article, where I used apertures of f/4 and f/32, you can see how diffraction is making the second shot less sharp. Here are the images when zoomed in to 100% view:

Here, you're seeing an effect called diffraction. Physics majors will know what I'm talking about, but diffraction is a foreign concept to most people. So, what is it?

Diffraction is actually quite simple. When you use a tiny aperture like f/32, you literally squeeze the light that passes through your lens. It ends up interfering with itself, growing blurrier, and resulting in photos that are noticeably less sharp.

At what aperture does diffraction start to become an issue? It depends upon a number of factors, including the size of your camera sensor and the size of your final print. Personally, on my full-frame camera, I see hints of diffraction at f/8, but it's not enough to bother me. I actually use even smaller apertures like f/11 and f/16 all the time when I have a close foreground in landscape photography. However, I try to avoid f/22 or smaller, since I lose too much detail at that point.

Diffraction isn't necessarily a huge problem, but it exists. Don't be afraid to take pictures at f/11 or f/16 just because you lose a little bit of sharpness. In many cases, the added depth of field is worth the tradeoff.

In macro photography, diffraction can be a bit more of a problem close-focusing actually makes your effective aperture a lot smaller than it really is. Although the math behind that gets a bit complicated, basically, shooting at f/11 at macro distances will show diffraction a lot more compared to if you're shooting a landscape at f/11. In other words, keep an eye out for diffraction when shooting macro.

Side Note

If your camera has a smaller sensor or a very high pixel density, you'll see diffraction sooner. On APS-C sensors (like on Nikon D3x00 series, Nikon D5x00 series, Fuji X-series, Sony A6x00 series, and many others), divide all these numbers by 1.5. On Micro Four-Thirds cameras (like those from Olympus and Panasonic), divide all these numbers by 2. In other words, I don't recommend using f/11 with a micro four-thirds camera, since it's equivalent to f/22 with a full-frame camera.

2. Lens Aberrations

Here's a fun one. For some reason, everyone wants to take sharp photos! One of the ways to do so is to minimize the visibility of lens aberrations. So, what are lens aberrations? Quite simply, they are image quality problems with a photo, caused by your lens.

Although most problems in photography are because of user error - things like missed focus, poor exposure, or a distracting composition - lens aberrations are entirely due to your equipment. They are fundamental, optical problems that you'll notice with any lens if you look too closely, although some lenses are better than others. For example, consider the image below:

What's going on here? In this crop, most of the lights look smeared rather than perfectly round. On top of that, the crop just isn't very sharp. That's lens aberration at work! The lights didn't look this blurry in the real world. My lens added this problem.

It's likely that your lenses are blurrier at certain apertures than others, and it's almost always blurrier in the corner of the image than the center. That's due to lens aberrations.

Aberrations can appear in several different forms. This article would be way too long if I explained every possible aberration in detail: vignetting, spherical aberration, field curvature, coma, distortion, color fringing, and more. Instead, it's more important to know why aberrations occur, including how your aperture setting can reduce them.

It starts with a simple fact: designing lenses is difficult. When the manufacturer fixes one problem, another tends to appear. It's no surprise that modern lens designs are extremely complex.

Unfortunately, even today's lenses aren't perfect. They tend to work fine in the center of an image, but everything gets worse near the edges. That's because lenses are especially difficult to design around the corners.

Here's a diagram that explains what I mean:

And that brings us to aperture.

Many people don't realize a simple fact about aperture: it literally blocks the light transmitted by the edges of your lens. (This doesn't lead to black corners in your photos, because the center regions of a lens can still transmit light to the edges of your camera sensor.)

As your aperture closes, more and more light from the sides of your lens will be blocked, never making it to your camera sensor. Only the light from the center area will pass through and form your photo! As the diagram above shows, this central area is far easier for camera manufacturers to design. The end result is that your photos will have fewer aberrations at smaller and smaller apertures.

How does this look in practice? See the photos below (heavy crops from the top-left corner):

What you're seeing above may look like an increase in sharpness, but it's really a decrease in aberrations. The end result? At f/5.6 on this particular lens, my photo is much sharper than at f/1.4.

Here's a key question: How does this balance out with diffraction, which harms sharpness increasingly more as your aperture gets narrower and narrower?

In practice, the answer is that most lenses end up sharpest around f/4, f/5.6, or f/8. Those "medium" apertures are small enough to block light from the edges of a lens, but they aren't so small that diffraction is a significant problem. However, you'll want to test this on your own equipment.

Of course, you can still take good photos at large apertures like f/1.4 or f/2. As I mentioned earlier, portrait photographers sometimes pay thousands of dollars to get a lens exactly for that purpose! So, don't lock your lens to f/5.6 just because it gives you a tad more corner sharpness up close. It's better to choose an aperture that gives you the right artistic look to the image.

Side Note

Some types of aberrations don't change much as you stop down, or they may even get slightly worse. Axial chromatic aberration, for example - color fringes near the edges of your frame - often work that way. This is normal. It happens because a small aperture doesn't inherently reduce aberrations; it simply blocks light that has passed through the edges of your lens. So, naturally, if the edges aren't the source of your problem, you won't see an improvement by stopping down.

3. Starburst and Sunstar Effects

Starbursts, also called sunstars, are beautiful elements that you'll find in certain photographs. Despite the odd names - one a type of candy; the other a type of starfish - I always try to capture them in my landscape photos. Here's an example:

How does this work? Essentially, for every aperture blade in your lens, you'll end up with a sunbeam. This only happens if you photograph a small, bright point of light, such as the sun when it is partly blocked. This is fairly common in landscape photography. If you want the strongest possible starburst, use a small aperture. Whenever the sun is in my photo, I almost always set f/16 purely to capture this effect.

Also, the starburst effect looks different from lens to lens. It all depends upon your aperture blades. If your lens has six aperture blades, you'll get six sunbeams. If your lens has eight aperture blades, you'll get eight sunbeams. And, if your lens has nine aperture blades, you'll get eighteen sunbeams.

Wait, what?

That's no typo. You always end up with an even number of sunbeams. If your lens has an odd number of aperture blades, you'll get double the number of sunbeams.

It sounds strange, but the reason is actually quite simple. In lenses with an even number of aperture blades (and a fully symmetrical design), half of the sunbeams will overlap the other half. So, you don't see all of them in your final photo.

Here's a diagram to show what I mean:

Most Nikon lenses have seven or nine aperture blades, resulting in 14 and 18 sunbeams respectively. Most Canon lenses have eight aperture blades, resulting in eight sunbeams. I took the photo above using the Nikon 20mm f/1.8G lens, which has 7 aperture blades. That's why the image has 14 sunbeams.

It's not just the number of blades that matters, though - their shape is also important. Some aperture blades are rounded (which results in a more pleasant out-of-focus background blur), and others are straight. If your goal is to capture good starbursts, straight aperture blades typically produce more defined rays of light.

Again, some lenses are better than others in this regard. For the best results, find a lens that's known to have good starbursts, and then set it to a small aperture like f/16. That's going to give you the strongest definition in your starbursts.

Finally, there's one last related effect that I wanted to mention briefly. When you shoot into the sun, you might end up with flare in your photographs, as shown below. Depending upon your chosen aperture, the size and shape of this lens flare may change slightly. This isn't a big deal, but it still exists.

4. Small Aperture and Unwanted Elements

When you shoot through things such as fences, dirty windows, plants, and even water droplets on your lens, you'll probably be disappointed by photos taken with a small aperture.

Small apertures like f/11 and f/16 give you such a large depth of field that you may accidentally include elements that you don't want to be in focus! For example, if you're shooting at a waterfall or by the ocean, an aperture of f/16 could render a tiny water droplet on your lens into a distinct, ugly blob:

In cases like that, it's better just to use a wider aperture - something like f/5.6, perhaps - in order to capture the water droplet so out-of-focus that it doesn't even appear in your image. In this particular case, you could simply wipe the droplet off, but that's not possible if you're shooting through something like a dirty window.

Side Note

You might have realized that this section is really just an extension of depth of field, and that's true! However, it's a bit of a special case, so I decided to mention it specifically.

Another example of shooting through things is when a piece of dust lands on your camera sensor. Unfortunately, as you change lenses, this is very common. Dust specks on your camera sensor will show up very clearly at small apertures like f/16, even if they're invisible at something larger, like f/4.

Luckily, they are very easy to remove in post-production software like Photoshop or Lightroom, though it can be annoying if you have to remove dozens of them from a single photo. That's why you should always keep your camera sensor clean.

5. Changes to Your Bokeh

What is bokeh? It's simply the quality of your background blur. If you take a lot of portraits, macro photos, or wildlife photos, you'll end up with out-of-focus backgrounds in most of your images. Naturally, you want them to look as good as possible! Different aperture settings will change the shape of your background blur.

Why is that? It's because the background blur of your photographs always takes on the shape of your aperture blades. So, if your aperture blades are shaped like a heart, you'll end up with heart-shaped background blur. Most of the time, that would qualify as distracting bokeh, although it's kind of cute in this photo of two fake tortoises:

On some lenses, aperture blades change shape a bit as they open and close. Large aperture settings (such as f/1.8) often have rounder background blur compared to smaller aperture settings. You'll also get more background blur at large apertures, since your depth of field is thinner.

If bokeh is something that matters to you, you'll want to test this on your particular lenses. Take some out-of-focus photos of a busy scene, each using a different aperture setting, and see which one looks the best. Most of the time, it will be the lens's widest aperture, but not always.

6. Focus Shift Issues

With certain lenses - even if you're in manual focus, and you don't move your focus ring - your point of focus may shift as you use smaller and smaller apertures.

Obviously, this isn't ideal. How do you tell if your lens has problematic focus shift? It's pretty easy. Here are the steps:

Put your camera on a tripod, and set your lens to manual focus.

Find an object with small details that extends backwards, and focus at the center of it. A table with a tablecloth works well.

Double check: When take a test photo and magnify it, you should see pixel-level details, as well as portions of the photo that are clearly out of focus.

Take a photo at your lens's widest aperture, and then at progressively smaller apertures. Be sure not to move your focus ring, and double check that you are using manual focus.

On your computer, zoom into 100% on these photos and see if the sharpest point of focus moves continuously farther back as you stop down. The more it moves, the worse your focus shift issue is.

You're done!

If your lens has extreme levels of focus shift, you'll want to compensate for it:

With your widest aperture, just focus like normal.

As you stop down the aperture, make sure to set your aperture first, then focus second (rather than focusing first). On DSLRs, we recommend focusing in live view at these apertures, because the viewfinder always focuses at the widest aperture. Mirrorless camera users don't need to worry about that.

With small apertures like f/8 and beyond, your depth of field will be large enough to hide any focus shift problems, so just focus like normal.

Side Note

When it comes down to it, focus shift is just another type of lens aberration. The edges of your lens may not focus light the same as the center, so, by stopping down - again, blocking light from the edges - your focus point changes slightly. That's the underlying reason for this effect.

7. Ease of Focusing

The autofocus system on your camera doesn't work well unless it receives plenty of light.

So, if you're shooting with a cheaper lens like a 70-300mm f/4.5-5.6, the largest aperture isn't bright enough to gather a lot of light. Focusing in dark conditions may be impacted. This is part of why a lot of pro photographers will use a more expensive lens like a 70-200mm f/2.8 instead.

You'll also enjoy a brighter viewfinder (on a DSLR) or a less noisy viewfinder (on a mirrorless camera) if your lens has a large maximum aperture. If you shoot a lot in low light, this can make it much easier to focus and compose your images.

8. Flash Exposure

When using speedlights or any kind of strobes, it is important to remember that aperture takes on a whole different role of controlling flash exposure. While shutter speed's role becomes controlling ambient light, aperture has an outsized impact on how much light from your flash is captured. Even though it's just a subset of exposure, we wanted to include it in this section, since flash is tightly correlated to lens aperture.

A Chart of Everything Aperture Does

Once you understand the information above, you will know everything aperture does to your photos. However, it may take a few re-reads of this article before it's all completely clear.

Practice is your best friend. Go outside, take some photos, and get a feel for aperture yourself.

If it helps, I compiled the main information in this article into a chart. This chart covers the most important effects of aperture in photography, as well as common terms that photographers use to describe their settings.

Note that to make this diagram easier to see, I did not darken or lighten any of the sample illustrations (as would occur in the real world). Instead, I simply wrote "brightest" through "darkest":

Although this chart is intentionally simplified, it covers all the basics that you need to know. Feel free to download and print this chart if you find it useful. Just right-click on the image, then select "save as," and pick the location where you want to store it.

Aperture FAQ

We put together some of the most frequently-asked questions related to aperture below.
How Does Aperture Affect Bokeh?
Bokeh refers to the quality of out-of-focus highlights of the image rendered by the camera lens. Using the maximum aperture of the lens will typically yield circular background highlights of large size, whereas stopping down the lens will typically result in highlights looking smaller and taking different shapes such as heptagon. These shapes depend on the number of aperture blades and their roundness. Here is an image of a 50mm f/1.4 prime lens stopped down to f/2.8 and f/4 apertures:

How Does Aperture Affect Sharpness?
Aperture is clearly a crucial setting in photography and it is possibly the single most important setting of all. Aperture affects several different parts of your photo, but you'll get the hang of everything fairly quickly. For a quick summary, a narrow aperture...

Makes your photos darker

Gives you more depth of field

Increases blur from diffraction

Decreases blur from most lens aberrations

Makes sensor dust more visible

Heightens the intensity of starbursts

...whereas a wide aperture does the opposite.

Soon, this won't be something that you even need to think about; you'll remember it all naturally. Personally, if I want a starburst effect in my photos, I immediately know to use an aperture of f/16. When I need as much light as possible, I set a larger aperture like f/2.8 or f/2 without a second thought. It doesn't take too much practice to get to that point.

With how important aperture is, it shouldn't be a surprise that, at Photography Life, we shoot in aperture-priority or manual mode all of the time. We simply never want the camera to select the aperture for us. It's just too important, and it is one of those basic settings that every beginner or advanced photographer needs to know in order to take the best possible images.

As always, it's best if you learn all this for yourself. Find something spectacular to capture, and put your new knowledge into practice. The more photos you take, the more you'll learn. Aperture is no exception.

Below are some other related posts you might enjoy:

Hopefully, you found that this article explains the basics of aperture in a way that is understandable and straightforward.

If you are ready to move on, the next important camera setting to learn is ISO, which we explain in Chapter 5 of our Photography Basics guide.

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What is Aperture? Understanding Aperture in Photography

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Aperture is one of the three pillars of photography, and certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

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Aperture and its effect on the opening of the lens

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-Kevin

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http://www.nikonusa.com/en/Learn-And-Explore/Article/g3cu6o1r/understanding-maximum-aperture.html

-Woo Jin

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Easy guide to understanding aperture(f-stop

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Easy guide to understanding aperture(f-stop

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http://www.redbubble.com/people/peterh111/journal/5725038-the-easy-guide-to-understanding-aperture-f-stop

-Willie

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Have you ever asked yourself a question similar to one of these?

What's with all the f/2.8 and f/1.4 and f/22 stuff people use in their Descriptions? Are they just being numerically anal or are they telling us something useful?

What's the freakin' difference between a 50mm f/1.4 lens and a 50mm f/1.8 lens? Why is one way more expensive than the other?

What do people mean when they describe a particular lens as being "fast"? Where is it going?

What do lenses have to do with aperture and f stop? Isn't that what a camera does?

What does "stopping down" mean?

If I'm meant to "stop down" why are the f numbers higher? Shouldn't they be lower?

Is "aperture" the same thing as f stop?

How does changing aperture change my photograph?

I shoot in Auto mode. Why do I need to know about aperture?

If you have, they are all good questions and they are all answered in this Tutorial. Seriously technically-minded readers should, however, stop right now and go and do something else lest they get irate at my basic, and potentially overly-simplistic, explanations.

My aim is merely this: learning about aperture and f stop is like learning to drive a car. Once you "get it" you never forget it. All it takes is an understanding of a few basic principles, so in my book it doesn't matter how they are expressed.

And if you reach an understanding of aperture and how you can control it, it is my firm view you will take your photography to the next level.

By the way, aperture and f stop are indeed references to the same thing. Aperture is the mechanism and f stop is the measure of engagement of the mechanism.
Seeing the light
Photography is not about selecting buttons and switches on a highly sophisticated piece of electronic and optical equipment.

Photography is about light.

Without light, there is no photograph. End of story. Light controls what you see in a photograph and how you see it. And because natural light changes constantly, we need to be able to control its intensity as it passes through the lens and into the camera as we take a photograph.

That is what aperture is. It's one mechanism by which we control the amount of light hitting the camera's sensor (or film). Other mechanisms, and I think there are only 2, are filters and shutter speed. (Filters are advanced stuff (see for example this), but shutter speed is not, so I discuss also the relationship between speed and aperture in this Tutorial.)

Controlling the light is important because shooting with too much light and you have an over-exposed image, and not enough light gives you an under-exposed image. We've all taken those, haven't we!?

Of course, your modern DSLR or Point & Shoot or Digital Compact, being a sophisticated and precise piece of equipment, can compensate for light automatically, should you choose to let it. But here's the rub: the camera has the artistic intelligence level of a mud brick, so it will make compensation adjustments purely as a numerical function and without regard to composition or depth of field.

Case in point: True story. I once met a photographer (not my girlfriend) who shoots weddings as a sort of pro-hobby to help out her brother's wedding video business. With no prior experience, she was given a brand new (full-frame) Canon 5D DSLR with an EF 24-105mm f/4 lens and told to leave it on Auto and just concentrate on composition. This she duly did, and was generally taking ok shots. But she was also confused. Every time she focused on a bride's face in a group shot, the whole group came out focused instead of just the bride. She wasn't very happy with the equipment as a result, and thought her brother had wasted $5000. It took some patience and some explaining about the role of aperture and f stop in taking a photograph because the expectation held by this Y Gen lady was that today's technology should do all that stuff. But bottom line was that if she had shot in Manual mode and set the aperture to f/4 or had shot in AV mode with aperture set at f/4 she would have achieved her aim of selective focus. I demonstrate and explain this later in this Tutorial.
How does the aperture control light?
Ever seen a science fiction movie where the scene is inside some fantastic spacecraft? The actor walks through a circular doorway and hits a button on the doorway wall and these sliding steel blades suddenly come out from all around the inside of the rim of the doorway and curl inwards towards the centre of the doorway until the space is completely closed up? (with that lovely steel-grinding sound effect!)

Well, that ain't science fiction because such a scene replicates the aperture mechanism of a camera lens (without the noise), as can be seen from this cross-section of the aperture mechanism of a Canon EF 50mm f1.8 II lens:

Notice the blades in the centre circle? Count 'em, there are 5. And they are actually called "aperture blades". They move in sync in and out depending on the aperture being set (either by you or by the camera). Notice also that the inside edges of the blades are not round and that the space allowing the light to go through the lens is thus not circular but instead pentagonal. So, whilst the Canon EF 50mm f1.8 II lens will produce exceptionally sharp images at the right aperture, the effect of having 5 non-rounded aperture blades is poor quality bokeh for out of focus (OOF) areas of the image, ie points of light in OOF areas will be pentagonal in shape, not circular. But hey, I can buy this lens brand new for $135, so it doesn't really matter that much.

By comparison, you'd want a macro lens to give you better quality OOF results. This comes at a price. For example, the $1200 Canon EF 100mm f2.8L IS Macro Lens has 9 round aperture blades, thus ensuring perfectly round points of light. (Just something to look for when considering that new lens.)

Anyway, back to the photo of the aperture mechanism. Any ideas of what the aperture setting (f stop) is? I'd say it's reasonably wide open.

Compare it with this chart, which shows the relative width of aperture according to f stop number. It is the standard "full-stop" f-number scale:

The lower the f stop number, the wider, or bigger, the aperture. Not to scale Aperture and shutter speed
As you can see from the above, an f stop of f/1.4 is really wide. It is letting a lot more light into the lens and ultimately onto the sensor than, say, f/8. Thus:

So, if someone tells you to "stop down", they are referring to decreasing the size of the aperture, which is achieved by increasing the f stop number. If I could wave a wand and get everyone to remember just one thing from this Tutorial, that principle would be it. Remember it and you have 95% "got it".

Given a low f stop number means a wider aperture which in turn means more light being allowed through the lens, changing the aperture for a particular evenly-exposed shot means you need to shoot faster to compensate (or increase the ISO). This is because shooting faster reduces the amount of light going through the lens. This is the relationship between aperture and shutter speed. And because both are based on logarithms and standardised, there is a direct link to how much compensation is necessary.

For example, and ignoring ISO for the moment, if you have an evenly exposed photograph shot hand-held at f/8 and 1/30th of a second, you could instead re-shoot it at a faster speed to get better definition and focus by also changing the aperture to, say, f/5.6.
"The aperture is proportional to the square root of accepted light, and thus inversely proportional to the square root of required exposure time, such that an aperture of f/2 allows for exposure times one quarter that of f/4."
Most modern digital cameras use a one-third f-stop increment scale, ie
Maximum and minimum apertures
So, changing the aperture from f/8 to f/5.6 equates to 1 full stop, and thus you need to increase the shutter speed by the same increment to maintain the even exposure. The numeric expression of the relationship between aperture and shutter speed has been described elsewhere as

Whatever.

All lenses have a maximum and a minimum aperture at which they can be used. These limits are known and clearly communicated by the lens manufacturer because each lens is different and thus the aperture range does affect a buyer's choice.

So, if a lens has a stated aperture range of f/2.8 to f/22 it means the smallest aperture at which the lens can be shot is f/22 (the minimum) and the largest aperture is f/2.8 (the maximum). That's a fairly typical range, as is f/4 to f/32.

When you see someone describe their lens as, say, the Canon EF 50mm f/1.4, they are telling you the image was shot with a lens with a maximum possible aperture of f/1.4. It doesn't mean they shot the image at that aperture, but it is a way of specifying which particular lens was used.

But what about zoom lenses and this type of description? Canon EF 70-300mm f/4-5.6 Zoom Lens. What that means is that when shooting with this lens at a 70mm focal length, the maximum aperture possible is f/4, whereas at 300mm the maximum possible aperture is f/5.6. This compares with the Canon EF 24-70mm f/2.8L Zoom Lens, which means that the maximum possible aperture is f/2.8 regardless of the focal length.

As a general proposition, it is also possible that Auto Focus is more precise the larger the maximum aperture. Canon, for example, certainly make this claim in relation to their EF lenses.

It is generally accepted that an aperture of f/2.8 is pretty wide. Since the wider the aperture, the more light, and the more shutter speed required to compensate, a lens with a maximum aperture of f/2.8 or more is described as "fast".

Such lenses are desirable because:

Better "stop-action" is achieved with faster shutter speeds, especially hand-held shots.

Lowly or poorly lit shots are made easier to achieve without noise from ramping up the ISO to compensate, and/or without a flash, and/or without a tripod.

But wait, there's more
And those are two reasons why people drool and salivate over such lenses as the Canon EF 24mm f/1.4L II, the Canon EF 50mm f/1.2L and the Canon 85mm f/1.2L II lens. The fact that these particular lenses are way out of our price range is also why people look at alternatives, such as the Canon EF 50mm f/1.4 and, say, the Sigma 50mm f/1.4 - much cheaper yet still fast.

There is also the Canon 50mm f/1.0L lens which has attained mythical status because it is no longer sold new. It can be obtained from between $3000 and $4500 second-hand and was, until recently, the fastest interchangeable SLR lens in the universe. That status is now held by the Leica Noctilux 50mm f/0.95 lens - released in 2008 and a steal at $11,000.

There's one other reason why a "fast" lens is desirable. Bokeh. The wider the aperture, the narrower the depth of field.

This can be simply demonstrated by the following two photographs. The first was taken at f/32, the second at f/5.6:

You get the picture.

Varying your aperture can also be a very effective way of shooting portraits. For example, this is an image of my youngest son:

It was shot hand-held with a Canon EOS 5D Mark II and a Sigma 50mm f/1.4 EX DG HSM lens, using available light indoors. The aperture I used was f/1.4. For a portrait like this, such a wide aperture allows so much light in through the lens that perfect focus is only achieved for a very narrow vertical focal plane, in this case Dylan's nose, ie at the front of his face. Every other feature of his face is blurred because none of it was on the same vertical focal plane as his nose (thank goodness!). In hindsight, I should have tried harder to focus on his eyes, but I had only recently acquired the lens and was basically experimenting.

The next shot was taken with the same camera and lens, under similar lighting conditions, but with an aperture of f/1.8. It is a casual shot of Linda, who has been a very good friend of mine for 30 years. She has just retired from 35 years of primary school teaching. Notice how on this occasion, the vertical focal plane is not as narrower at f/1.8 as it was with Dylan at f/1.4. It's not much of a difference but it is enough of a difference to affect the outcome of a portrait shot.

Now compare those shots with the following portrait, Leila, shot by Tatiana with a Canon 5D and a Canon 85mm f/1.8 Lens at f/2:

Notice that Tatiana has been very selective in her use of a slightly wider aperture and the angle of the profile to get Leila's eye and cheek in focus.

All 3 of the above shots were taken in the Manual shooting mode. That is, the aperture was deliberately chosen. Would the camera have chosen the same apertures had we been shooting in Auto? Absolutely not. (See also the discussion below on shooting in Aperture Priority mode.)
Ducking Across The Yellow Brick Road Morning Dew Taj Mahal Bench
Aperture Priority
Canon 5D Mark II, Canon EF 24-105mm f/4 IS Lens at f/9 Group f/64
Conclusion
Canon 5D Mark II, Canon EF 180mm f/3.5 Macro Lens at f/3.5 Acknowledgments
History
Canon 5D, Canon EF 85mm f1.2L USM lens at f/1.2
All 3 were also all shot from roughly the same distance from the subjects, but you can (hopefully) imagine that the farther away the subject, the narrower the aperture needs to be. For example, the next shot was taken by my good friend Crispin with his new camera, the Canon 1D Mark IV, and a Canon EF 70-200mm f/2.8L IS Zoom Lens + 2.0 x converter, at a focal length of 400mm (!). He used an aperture of f/5.6 but even so, there is a drop-off of focus on Avril's face.

Crispin understands aperture very well. I know this because his photography stands out for his control of DOF through the aperture he selects and given the lens he selects for the shot. For example, he understands the creative effect a wide aperture can have on his DOF:

An interesting thing about that last shot, taken by Crispin at f/9, is the broad DOF. In fact, setting an aperture of smaller than f/9 on the 5D Mark II, ie f/11, f/16 and so on, will not achieve any greater DOF. This is due to the Diffraction Principle, which applies to DSLRs with a large amount of pixels available to the sensor. In the case of the full frame 5D Mark II, 21.6 megapixels are competing for the narrow light created by such small apertures, so much so that definition is not improved. And this is why I would only shoot at f/11 and down further when using my own 5D Mark II to prolong a long exposure. If that camera has a downside, the application of the Diffraction Principle is it.

I'm a strong advocate of not shooting in Auto mode (where the camera makes all the decisions on settings) unless circumstances dictate quick, responsive, shooting. I shoot almost exclusively in Manual mode (where I make all the decisions), but I also shoot in Aperture Priority mode when using my film SLR, the Canon EOS-3. What is Aperture Priority?

Turning your camera's Mode Dial to AV (which stands for Aperture value) means that you set the aperture you want and the camera compensates by making the decisions on shutter speed. This is a particularly good way of ensuring you achieve the DOF you want from your image. (Just remember that, as with Shutter Priority mode (TV) and Auto mode, the camera will compensate for even exposure, whereas in some cases you may not be looking for that level of light control. That's why I shoot in Manual.)

Related to this, many of the newer digital cameras now offer DOF preview, which means that once you have composed and focused your shot, you can press a button on the camera with a finger on your left hand, whilst scrolling through the various f stops with a finger on your right hand, and see the changes to DOF through the viewfinder as you scroll through the apertures. Cool.

This story would not be complete unless I quickly mention Group f/64. One hundred years ago, Pictorialist photography was the thing. Grainy, soft focus, dark-toned images, created in the darkroom by a variety of manual techniques, was the height of photographic fashion. Much like the opportunities provided by today's Photoshop with its textures and layers, back then such creativity boomed in the hands of the motivated. Another explanation I've heard of the birth of Pictorialism was that it was pursued to demonstrate the legitimacy of photography as a valid form of art, in part to overcome the overwhelming contemporary perceptions of photography stemming from Kodak enabling the masses to literally point and shoot with the mass-produced Box Brownie.

Group f/64 was a conclave of photographers who railed against pictorialism, among the founders being Ansel Adams and Edward Weston. Their aim was to promote the cause of photography as it was shot. And they shot as their eyes saw, with perfect focus throughout the frame - foreground, background, and everywhere in between. Their cameras were large format and f/64 was the smallest aperture possible to give that clarity, especially in landscapes. We digital camera users can do nought but dream about using f/64. Either that or dream about picking up a few long lost Ansel Adams negatives in a garage sale. Now wouldn't that make your day?

Well, I've looked at the questions at the start of the Tutorial and I think I've answered them. I hope the answers are able to facilitate anyone's understanding.

Cheers
Peter

The 2 flower images were taken by Fir0002 and are used with permission granted under the terms of the Wikipedia GNU Free Documentation License.

The image of the aperture mechanism of a Canon EF 50mm f1.8 II Lens was taken by Adam Wysocki and is used with permission granted under the terms of the Wikipedia GNU Free Documentation License.

The graphic of the relative f stop sizes was created by Chris Buckley and is used with permission granted under the terms of the Wikipedia GNU Free Documentation License.

The images taken by Tatiana and Crispin are used with their kind permission.

13 August 2010 - Tutorial published
20 August 2010 - Additional content on Aperture Priority added

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The Easy Guide To Understanding Aperture (f Stop) by Peter Hill

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Have you ever asked yourself a question similar to one of these? What's with all the f/2.8 and f/1.4 and f/22 stuff people use in their Descriptions? Are they just being numerically anal or are they telling us something useful? What's the freakin' difference between a 50mm f/1.4 lens and a 50mm f/1.8 lens?

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-Shwun

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Depth of field refers to the range of distance that appears acceptably sharp. It varies depending on camera type, aperture and focusing distance, although print size and viewing distance can also influence our perception of depth of field. This tutorial is designed to give a better intuitive and technical understanding for photography, and provides a depth of field calculator to show how it varies with your camera settings.

The depth of field does not abruptly change from sharp to unsharp, but instead occurs as a gradual transition. In fact, everything immediately in front of or in back of the focusing distance begins to lose sharpness - even if this is not perceived by our eyes or by the resolution of the camera.

CIRCLE OF CONFUSION

Since there is no critical point of transition, a more rigorous term called the " circle of confusion" is used to define how much a point needs to be blurred in order to be perceived as unsharp. When the circle of confusion becomes perceptible to our eyes, this region is said to be outside the depth of field and thus no longer "acceptably sharp." The circle of confusion above has been exaggerated for clarity; in reality this would be only a tiny fraction of the camera sensor's area.

When does the circle of confusion become perceptible to our eyes? An acceptably sharp circle of confusion is loosely defined as one which would go unnoticed when enlarged to a standard 8x10 inch print, and observed from a standard viewing distance of about 1 foot.

At this viewing distance and print size, camera manufacturers assume a circle of confusion is negligible if no larger than 0.01 inches (when enlarged). As a result, camera manufacturers use the 0.01 inch standard when providing lens depth of field markers (shown below for f/22 on a 50mm lens). In reality, a person with 20/20 vision or better can distinguish features 1/3 this size, and so the circle of confusion has to be even smaller than this to achieve acceptable sharpness throughout.

A different maximum circle of confusion also applies for each print size and viewing distance combination. In the earlier example of blurred dots, the circle of confusion is actually smaller than the resolution of your screen for the two dots on either side of the focal point, and so these are considered within the depth of field. Alternatively, the depth of field can be based on when the circle of confusion becomes larger than the size of your digital camera's pixels.

Note that depth of field only sets a maximum value for the circle of confusion, and does not describe what happens to regions once they become out of focus. These regions are also called "bokeh," from Japanese (pronounced bo-ké). Two images with identical depth of field may have significantly different bokeh, as this depends on the shape of the lens diaphragm. In reality, the circle of confusion is usually not actually a circle, but is only approximated as such when it is very small. When it becomes large, most lenses will render it as a polygonal shape with 5-8 sides.

CONTROLLING DEPTH OF FIELD

Although print size and viewing distance influence how large the circle of confusion appears to our eyes, aperture and focusing distance are the two main factors that determine how big the circle of confusion will be on your camera's sensor. Larger apertures (smaller F-stop number) and closer focusing distances produce a shallower depth of field. The following test maintains the same focus distance, but changes the aperture setting:

note: images taken with a 200 mm lens (320 mm field of view on a 35 mm camera)

CLARIFICATION: FOCAL LENGTH AND DEPTH OF FIELD

Note that focal length has not been listed as influencing depth of field, contrary to popular belief. Even though telephoto lenses appear to create a much shallower depth of field, this is mainly because they are often used to magnify the subject when one is unable to get closer. If the subject occupies the same fraction of the image (constant magnification) for both a telephoto and a wide angle lens, the total depth of field is virtually* constant with focal length! This would of course require you to either get much closer with a wide angle lens or much farther with a telephoto lens, as demonstrated in the following chart:

Focal Length (mm)

Focus Distance (m)

Depth of Field (m)

Note: Depth of field calculations are at f/4.0 on a camera with a 1.6X crop factor,
using a circle of confusion of 0.0206 mm.

Note how there is indeed a subtle change for the smallest focal lengths. This is a real effect, but is negligible compared to both aperture and focusing distance. Even though the total depth of field is virtually constant, the fraction of the depth of field which is in front of and behind the focus distance does change with focal length, as demonstrated below:

This exposes a limitation of the traditional DoF concept: it only accounts for the total DoF and not its distribution around the focal plane, even though both may contribute to the perception of sharpness. Note how a wide angle lens provides a more gradually fading DoF behind the focal plane than in front, which is important for traditional landscape photographs.

Longer focal lengths may also appear to have a shallower depth of field because they enlarge the background relative to the foreground (due to their narrower angle of view). This can make an out of focus background look even more out of focus because its blur has become enlarged. However, this is another concept entirely, since depth of field only describes the sharp region of a photo - not the blurred regions.

On the other hand, when standing in the same place and focusing on a subject at the same distance, a longer focal length lens will have a shallower depth of field (even though the pictures will frame the subject entirely differently). This is more representative of everyday use, but is an effect due to higher magnification, not focal length.

Depth of field also appears shallower for SLR cameras than for compact digital cameras, because SLR cameras require a longer focal length to achieve the same field of view (see the tutorial on digital camera sensor sizes for more on this topic).

* Technical Note: We describe depth of field as being virtually constant because there are limiting cases where this does not hold true. For focal distances resulting in high magnification, or very near the hyperfocal distance, wide angle lenses may provide a greater DoF than telephoto lenses. On the other hand, at high magnification the traditional DoF calculation becomes inaccurate due to another factor: pupil magnification. This reduces the DoF advantage for most wide angle lenses, and increases it for telephoto and macro lenses. At the other limiting case, near the hyperfocal distance, the increase in DoF arises because the wide angle lens has a greater rear DoF, and can thus more easily attain critical sharpness at infinity.

CALCULATING DEPTH OF FIELD

In order to calculate the depth of field, one needs to first decide on an appropriate value for the maximum allowable circle of confusion. This is based on both the camera type (sensor or film size), and on the viewing distance / print size combination. Needless to say, knowing what this will be ahead of time often isn't straightforward. Try out the depth of field calculator tool to help you find this for your specific situation.

DEPTH OF FOCUS & APERTURE VISUALIZATION

Another implication of the circle of confusion is the concept of depth of focus (also called the "focus spread"). It differs from depth of field because it describes the distance over which light is focused at the camera's sensor, as opposed to the subject:

Diagram depicting depth of focus versus camera aperture. The purple lines comprising the edge of each shaded region represent the extreme angles at which light could potentially enter the aperture. The interior of the purple shaded regions represents all other possible angles.

The key concept is this: when an object is in focus, light rays originating from that point converge at a point on the camera's sensor. If the light rays hit the sensor at slightly different locations (arriving at a disc instead of a point), then this object will be rendered as out of focus - and increasingly so depending on how far apart the light rays are.

OTHER NOTES

Why not just use the smallest aperture (largest number) to achieve the best possible depth of field? Other than the fact that this may require prohibitively long shutter speeds without a camera tripod, too small of an aperture softens the image by creating a larger circle of confusion (or " Airy disk") due to an effect called diffraction - even within the plane of focus. Diffraction quickly becomes more of a limiting factor than depth of field as the aperture gets smaller. Despite their extreme depth of field, this is also why "pinhole cameras" have limited resolution.

For macro photography (high magnification), the depth of field is actually influenced by another factor: pupil magnification. This is equal to one for lenses which are internally symmetric, although for wide angle and telephoto lenses this is greater or less than one, respectively. A greater depth of field is achieved (than would be ordinarily calculated) for a pupil magnification less than one, whereas the pupil magnification does not change the calculation when it is equal to one. The problem is that the pupil magnification is usually not provided by lens manufacturers, and one can only roughly estimate it visually.

OTHER WEBSITES & FURTHER READING

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Understanding Depth of Field in Photography

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Depth of field refers to the range of distance that appears acceptably sharp. It varies depending on camera type, aperture and focusing distance, although print size and viewing distance can also influence our perception of depth of field.

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http://digital-photography-school.com/aperture/

- Su

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Over the last couple of weeks I've been writing a series of posts on elements that digital photographers need to learn about in order to get out of Auto mode and learn how to manually set the exposure of their shots. I've largely focussed upon three elements of the ' exposure triangle' - ISO, Shutter Speed and . I've previously written about the first two and today would like to turn our attention to Aperture.

Before I start with the explanations let me say this. If you can master aperture you put into your grasp real creative control over your camera. In my opinion - aperture is where a lot of the magic happens in photography and as we'll see below, changes in it can mean the difference between one dimensional and multi dimensional shots.

What is Aperture?

Put most simply - Aperture is 'the opening in the lens.'

When you hit the shutter release button of your camera a hole opens up that allows your cameras image sensor to catch a glimpse of the scene you're wanting to capture. The aperture that you set impacts the size of that hole. The larger the hole the more light that gets in - the smaller the hole the less light.

Aperture is measured in 'f-stops'.

You'll often see them referred to here at Digital Photography School as f/number - for example f/2.8, f/4, f/5.6,f/8,f/22 etc. Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens (and the amount of light getting through). Keep in mind that a change in shutter speed from one stop to the next doubles or halves the amount of light that gets in also - this means if you increase one and decrease the other you let the same amount of light in - very handy to keep in mind).

One thing that causes a lot of new photographers confusion is that large apertures (where lots of light gets through) are given f/stop smaller numbers and smaller apertures (where less light gets through) have larger f-stop numbers. So f/2.8 is in fact a much larger aperture than f/22. It seems the wrong way around when you first hear it but you'll get the hang of it.

Depth of Field and Aperture

There are a number of results of changing the aperture of your shots that you'll want to keep in mind as you consider your setting but the most noticeable one will be the depth of field that your shot will have.

Depth of Field (DOF) is that amount of your shot that will be in focus. Large depth of field means that most of your image will be in focus whether it's close to your camera or far away. For example the landscape shot above has an aperture of f/16 and the result is that both the mountain in the background and the boats in the foreground remain in focus.

Small (or shallow) depth of field means that only part of the image will be in focus and the rest will be fuzzy (like in the portrait at the top of this post. You'll see in it that the subjects eyes are in focus but the background is blurred. Even her hair which is only a little behind her eyes is blurred. This is a very shallow depth of field and was taken with an aperture of f1.8).

Similarly this creative birth announcement image was shot at f1.8 and again you see the shallow depth of field with the ultrasound in focus but everything else blurred.

Here's one more example with an even wider aperture of f1.2 that leaves the guitar in focus but everything else blurred.

Aperture has a big impact upon depth of field. Large aperture (remember it's a smaller number) will decrease depth of field while small aperture (larger numbers) will give you larger depth of field.

It can be a little confusing at first but the way I remember it is that small numbers mean small DOF and large numbers mean large DOF.

Let me illustrate this with two pictures I took earlier this week in my garden of two flowers.

The first picture on the left was taken with an aperture of f/22 and the second one was taken with an aperture of f/2.8. The difference is quite obvious. The f/22 picture has both the flower and the bud in focus and you're able to make out the shape of the fence and leaves in the background.

The f/2.8 shot on the right has the left flower in focus (or parts of it) but the depth of field is very shallow and the background is thrown out of focus and the bud to the right of the flower is also less in focus due to it being slightly further away from the camera when the shot was taken.

The best way to get your head around aperture is to get your camera out and do some experimenting. Go outside and find a spot where you've got items close to you as well as far away and take a series of shots with different aperture settings from the smallest setting to the largest. You'll quickly see the impact that it can have and the usefulness of being able to control aperture.

Some styles of photography require large depths of field (and small Apertures)

For example in most landscape photography you'll see small aperture settings (large numbers) selected by photographers. This ensures that from the foreground to the horizon is relatively in focus.

On the other hand in portrait photography it can be very handy to have your subject perfectly in focus but to have a nice blurry background in order to ensure that your subject is the main focal point and that other elements in the shot are not distracting. In this case you'd choose a large aperture (small number) to ensure a shallow depth of field.

Macro photographers tend to be big users of large apertures to ensure that the element of their subject that they are focusing in on totally captures the attention of the viewer of their images while the rest of the image is completely thrown out of focus.

I hope that you found this introduction to Aperture in Digital Photography helpful. Be sure to also check out our introduction to Shutter Speed and introduction to ISO.

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Introduction to Aperture in Photography - dPS

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Over the last couple of weeks I've been writing a series of posts on elements that digital photographers need to learn about in order to get out of Auto mode and learn how to manually set the exposure of their shots. I've largely focussed upon three elements of the ' exposure triangle' - ISO, Shutter Speed and .

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Examples of aperture and depth of field 

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Examples of aperture and depth of field 

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- Sophie

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Photographic examples of aperture and depth of field | DigicamGuides.com

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See photographic examples of what happens to depth of field when you change the aperture setting on your digital camera.

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http://digital-photography-school.com/aperture/

-Woo Jin

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https://photographylife.com/what-is-aperture-in-photography

-Richard

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https://photographylife.com/what-is-aperture-in-photography

-Willie

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Aperture is one of the three pillars of photography (the other two being Shutter Speed and ISO, which are two other chapters in our Photography Basics guide). Of the three, aperture is certainly the most important. In this article, we go through everything you need to know about aperture and how it works.

What is Aperture?

Aperture can be defined as the opening in a lens through which light passes to enter the camera. It is an easy concept to understand if you just think about how your eyes work. As you move between bright and dark environments, the iris in your eyes either expands or shrinks, controlling the size of your pupil.

In photography, the "pupil" of your lens is called aperture. You can shrink or enlarge the size of the aperture to allow more or less light to reach your camera sensor. The image below shows an aperture in a lens:

Aperture can add dimension to your photos by controlling depth of field. At one extreme, aperture gives you a blurred background with a beautiful shallow focus effect. This is very popular for portrait photography.

At the other extreme, it will give you sharp photos from the nearby foreground to the distant horizon. Landscape photographers use this effect a lot.

On top of that, the aperture you choose also alters the exposure of your images by making them brighter or darker.

Aperture Explained in Video

If you prefer to understand how aperture works visually, we put together a video for you that goes through most of the basics. In the video, we go through what aperture is, how it works, and every effect that aperture has in photography. (These points are also covered further down in this article.)

How Aperture Affects Exposure

Aperture has several effects on your photographs. Perhaps the most obvious is the brightness, or exposure, of your images. As aperture changes in size, it alters the overall amount of light that reaches your camera sensor - and therefore the brightness of your image.

A large aperture (a wide opening) will pass a lot of light, resulting in a brighter photograph. A small aperture does just the opposite, making a photo darker. Take a look at the illustration below to see how it affects exposure:

In a dark environment - such as indoors or at night - you will probably want to select a large aperture to capture as much light as possible. This is the same reason why people's pupils dilate when it starts to get dark; pupils are the aperture of our eyes.

How Aperture Affects Depth of Field

The other critical effect of aperture is depth of field. Depth of field is the amount of your photograph that appears sharp from front to back. Some images have a "thin" or "shallow" depth of field, where the background is completely out of focus. Other images have a "large" or "high" depth of field, where both the foreground and background are sharp.

For example, here is an image with a shallow depth of field:

In the image above, you can see that the girl is in focus and appears sharp, while the background is completely out of focus. My choice of aperture played a big role here. I specifically used a large aperture in order to create a shallow focus effect (yes, the larger your aperture, the bigger this effect). This helped me bring the attention of the viewer to the subject, rather than busy background. Had I used a narrower aperture, the subject would not be separated from the background as effectively.

One trick to remember this relationship: a large aperture results in a large amount of both foreground and background blur. This is often desirable for portraits, or general photos of objects where you want to isolate the subject. Sometimes you can frame your subject with foreground objects, which will also look blurred relative to the subject, as shown in the example below:

Quick Note: The appearance of the out-of-focus areas (AKA whether it looks good or not) is often referred to as " bokeh". Bokeh is the property of the lens, and some lenses have better bokeh than others. This article explains how to get better bokeh as a photographer. Even though some lenses are better than others, almost all lenses are capable of a nice shallow focus effect if you use a large aperture and get close enough to your subject.

On the other hand, a small aperture results in a small amount of background blur, which is typically ideal for some types of photography such as landscape and architecture. In the landscape photo below, I used a small aperture to ensure that both my foreground and background were as sharp as possible from front to back:

Here is a quick comparison that shows the difference between using a large vs a small aperture and what it does to your depth of field:

As you can see, in the photograph on the left, only the head of the lizard appears in focus and sharp, while the background and foreground are both transitioning into blur. Meanwhile, the photo on the right has everything from front to back appearing in focus. This is what using large vs small aperture does to photographs.

What Are F-Stop and F-Number?

So far, we have only discussed aperture in general terms like large and small. However, it can also be expressed as a number known as "f-number" or " f-stop ", with the letter "f" appearing before the number, such as f/8.

Most likely, you have noticed aperture written this way on your camera before. On your LCD screen or viewfinder, your aperture will usually look something like this: f/2, f/3.5, f/8, and so on. Some cameras omit the slash and write f-stops like this: f2, f3.5, f8, and so on. For example, the Nikon camera below is set to an aperture of f/8:

So, f-stops are a way of describing the size of the aperture for a particular photo. If you want to find out more about this subject, we have a comprehensive article on f-stop that explains why it's written that way and is worth checking out.

Large vs Small Aperture

There's a catch - one important part of aperture that confuses beginning photographers more than anything else. This is something you really need to pay attention to and get correct: Small numbers represent large apertures, and large numbers represent small apertures!

That's not a typo. For example, f/2.8 is larger than f/4 and much larger than f/11. Most people find this awkward, since it goes against our basic intuition. Nevertheless, this is a fact of photography. Take a look at this chart:

This causes a huge amount of confusion among photographers, because it's completely the reverse of what you would expect at first. However, there is a reasonable and simple explanation that should make it much clearer to you: Aperture is a fraction.

When you are dealing with an f-stop of f/16, for example, you can think of it like the fraction 1/16th. Hopefully, you already know that a fraction like 1/16 is clearly much smaller than the fraction 1/4. For this exact reason, an aperture of f/16 is smaller than f/4. Looking at the front of your camera lens, this is what you'd see:

So, if photographers recommend a large aperture for a particular type of photography, they're telling you to use something like f/1.4, f/2, or f/2.8. And if they suggest a small aperture for one of your photos, they're recommending that you use something like f/8, f/11, or f/16.

How to Pick the Right Aperture

Now that you're familiar with large vs small apertures, how do you know what aperture to use for your photos? Let's revisit two of the most important effects of aperture: exposure and depth of field. First, here is a quick diagram to refresh your memory on how aperture affects the exposure of an image:

If you've read the prior chapter in our Photography Basics guide covering shutter speed, you already know that aperture isn't the only way to change how bright a photo is. Nevertheless, it plays an important role. In the graphic above, if I didn't allow myself to change any other camera settings like shutter speed or ISO, the optimal aperture would be f/5.6.

In a darker environment, where you aren't capturing enough light, the optimal aperture would change. For example, you may want to use a large aperture like f/2.8 at night, just like how our eye's pupils dilate to capture every last bit of light:

As for depth of field, recall that a large aperture value like f/2.8 will result in a large amount of background blur (ideal for shallow focus portraits), while values like f/8, f/11, or f/16 will give you a lot more depth of field (ideal for landscapes and architectural photography).

In fact, depth of field is the part of aperture that I recommend thinking about the most. My process for almost every photo I take goes like this:

Ask myself how much depth of field I want

Set an aperture that achieves it

Set a shutter speed that makes my photo the proper brightness

If that shutter speed leads to unsharp photos thanks to too much motion blur, dial back the shutter speed and raise my ISO instead

Win photo contest :)

Here is a quick chart that lays out everything we've covered so far:

Setting Aperture in Your Camera

If you haven't guessed it already, we highly recommend selecting your aperture manually as a photographer. If you allow the camera to set it automatically, you are likely to end up with the completely wrong depth of field in your image.

There are two modes in photography which allow you to select the aperture manually. These are aperture-priority mode and manual mode. Aperture-priority mode is written as "A" or "Av" on most cameras, while manual is written as "M." Usually, you can find these on the top dial of your camera (read more also in our article on camera modes):

In aperture-priority mode, you select the desired aperture, and the camera automatically selects your shutter speed. You can select ISO manually or automatically. Aperture priority mode is great for everyday photography, where you rarely need to worry about any camera settings other than aperture. It's what I use 95% of the time even for professional landscape and portrait photography.

In manual mode, you select both aperture and shutter speed manually. (ISO can again be manual or auto.) Manual mode takes more time and usually gives you the same results as aperture priority anyway. It's only needed in special situations where you need a consistent exposure from shot to shot, or when the camera's meter is messing up. I use it for Milky Way photography and for portraiture with flash.

Minimum and Maximum Aperture of Lenses

Every lens has a limit on how large or how small the aperture can get. If you take a look at the specifications of your lens, it should say what the maximum and minimum apertures are. For almost everyone, the maximum aperture will be more important, because it tells you how much light the lens can gather at its maximum (basically, how dark of an environment you can take photos - and how much of a shallow focus effect you can achieve).

A lens that has a maximum aperture of f/1.4 or f/1.8 is considered to be a "fast" lens, because it can pass through more light than, for example, a lens with a "slow" maximum aperture of f/4.0. That's why lenses with large apertures usually cost more.

By comparison, the minimum aperture is not that important, because almost all modern lenses can provide at least f/16 at the minimum. You will rarely need anything smaller than that for day-to-day photography.

With some zoom lenses, the maximum aperture will change as you zoom in and out. For example, with the Nikon 18-55mm f/3.5-5.6 AF-P lens, the largest aperture shifts gradually from f/3.5 at the wide end to just f/5.6 at the longer focal lengths. More expensive zooms tend to maintain a constant maximum aperture throughout their zoom range, like the Nikon 24-70mm f/2.8. Prime lenses also tend to have larger maximum apertures than zoom lenses, which is one of their major benefits.

The maximum aperture of a lens is so important that it's included in the name of the lens itself. Sometimes, it will be written with a colon rather than a slash, but it means the same thing (like the Nikon 50mm 1:1.4G below).

Examples of Which Aperture to Use

Now that we have gone through a thorough explanation of how aperture works and how it affects your images, let's take a look at the situations where you'd want to use various f-stops.

f/0.95 - f/1.4 - Such "fast" maximum apertures are only available on premium prime lenses, allowing them to gather as much light as possible. This makes them ideal for any kind of low-light photography (such as photographing the night sky, wedding receptions, portraits in dimly-lit rooms, corporate events, etc). With such wide f-stops, you will get very shallow depth of field at close distances, where the subject will appear separated from the background.

f/1.8 - f/2.0 - Some enthusiast-grade prime lenses are limited to f/1.8, which still has very good low-light capabilities. Also, if your purpose is to yield aesthetically-pleasing images with shallow focus, these lenses be of tremendous value. Shooting between f/1.8 and f/2 typically turns your backgrounds nice and creamy for portraiture and other similar types of photography.

f/2.8 - f/4 - Most zoom lenses are limited to a maximum aperture of f/2.8 to f/4 at best. While they are not as capable as f/1.4 lenses in terms of light-gathering capabilities, they are still enough to shoot in reasonably low light conditions, especially if the lens or camera has image stabilization. You'll get some subject separation at these apertures, but usually not enough to make the background completely fuzzy. Such apertures are great for travel, sports, and wildlife photography.

f/5.6 - f/8 - This is the right starting point for most landscape and architectural photography. It's also ideal for documentary and portrait photography where you don't want a blurry background. Also, most lenses are sharpest around f/5.6, which doesn't matter as much as getting the right depth of field, but is still nice.

f/11 - f/16 - Typically used for photographing scenes where as much depth of field as possible is needed, like macro photography or landscape photography with a nearby foreground. Even though these apertures offer more depth of field, they do lose some low-level sharpness due to the effect of lens diffraction.

f/22 and smaller - Only shoot at such small apertures if you know what you are doing. Sharpness suffers greatly at f/22 and smaller apertures because of diffraction, so you should avoid using them when possible. If you need to get more depth of field, it is usually best to move away from your subject or use a focus stacking technique instead.

You've made it this far, but are you willing to learn more about aperture? So far we have only touched the basics, but aperture does so much more to your photographs. Let's take a closer look.

Everything Aperture Does to Your Photos

Ever wondered how else aperture affects your photographs aside from brightness and depth of field? In this part of the article, we will go through all other ways aperture impacts your images, from sharpness to sunstars, and tell you exactly why each matters.

Before diving into too many specifics, here's a quick list of everything aperture affects in photography:

The brightness / exposure of your photos and depth of field, as discussed so far

Sharpness loss due to diffraction

Sharpness loss due to lens quality

Starburst effects on bright lights

Visibility of camera sensor dust specks

The quality of background highlights (bokeh)

Focus shift on some lenses

Ability to focus in low light (under some conditions)

Controlling the amount of light from the flash

1. The Negative Effect of Diffraction

So, if you're a landscape photographer who wants everything as sharp as possible, you should use your lens's smallest aperture, like f/22 or f/32 to get maximum depth of field, right?

No!

If we go back and take a close look at the photo of the lizard from earlier in this article, where I used apertures of f/4 and f/32, you can see how diffraction is making the second shot less sharp. Here are the images when zoomed in to 100% view:

Here, you're seeing an effect called diffraction. Physics majors will know what I'm talking about, but diffraction is a foreign concept to most people. So, what is it?

Diffraction is actually quite simple. When you use a tiny aperture like f/32, you literally squeeze the light that passes through your lens. It ends up interfering with itself, growing blurrier, and resulting in photos that are noticeably less sharp.

At what aperture does diffraction start to become an issue? It depends upon a number of factors, including the size of your camera sensor and the size of your final print. Personally, on my full-frame camera, I see hints of diffraction at f/8, but it's not enough to bother me. I actually use even smaller apertures like f/11 and f/16 all the time when I have a close foreground in landscape photography. However, I try to avoid f/22 or smaller, since I lose too much detail at that point.

Diffraction isn't necessarily a huge problem, but it exists. Don't be afraid to take pictures at f/11 or f/16 just because you lose a little bit of sharpness. In many cases, the added depth of field is worth the tradeoff.

In macro photography, diffraction can be a bit more of a problem close-focusing actually makes your effective aperture a lot smaller than it really is. Although the math behind that gets a bit complicated, basically, shooting at f/11 at macro distances will show diffraction a lot more compared to if you're shooting a landscape at f/11. In other words, keep an eye out for diffraction when shooting macro.

Side Note

If your camera has a smaller sensor or a very high pixel density, you'll see diffraction sooner. On APS-C sensors (like on Nikon D3x00 series, Nikon D5x00 series, Fuji X-series, Sony A6x00 series, and many others), divide all these numbers by 1.5. On Micro Four-Thirds cameras (like those from Olympus and Panasonic), divide all these numbers by 2. In other words, I don't recommend using f/11 with a micro four-thirds camera, since it's equivalent to f/22 with a full-frame camera.

2. Lens Aberrations

Here's a fun one. For some reason, everyone wants to take sharp photos! One of the ways to do so is to minimize the visibility of lens aberrations. So, what are lens aberrations? Quite simply, they are image quality problems with a photo, caused by your lens.

Although most problems in photography are because of user error - things like missed focus, poor exposure, or a distracting composition - lens aberrations are entirely due to your equipment. They are fundamental, optical problems that you'll notice with any lens if you look too closely, although some lenses are better than others. For example, consider the image below:

What's going on here? In this crop, most of the lights look smeared rather than perfectly round. On top of that, the crop just isn't very sharp. That's lens aberration at work! The lights didn't look this blurry in the real world. My lens added this problem.

It's likely that your lenses are blurrier at certain apertures than others, and it's almost always blurrier in the corner of the image than the center. That's due to lens aberrations.

Aberrations can appear in several different forms. This article would be way too long if I explained every possible aberration in detail: vignetting, spherical aberration, field curvature, coma, distortion, color fringing, and more. Instead, it's more important to know why aberrations occur, including how your aperture setting can reduce them.

It starts with a simple fact: designing lenses is difficult. When the manufacturer fixes one problem, another tends to appear. It's no surprise that modern lens designs are extremely complex.

Unfortunately, even today's lenses aren't perfect. They tend to work fine in the center of an image, but everything gets worse near the edges. That's because lenses are especially difficult to design around the corners.

Here's a diagram that explains what I mean:

And that brings us to aperture.

Many people don't realize a simple fact about aperture: it literally blocks the light transmitted by the edges of your lens. (This doesn't lead to black corners in your photos, because the center regions of a lens can still transmit light to the edges of your camera sensor.)

As your aperture closes, more and more light from the sides of your lens will be blocked, never making it to your camera sensor. Only the light from the center area will pass through and form your photo! As the diagram above shows, this central area is far easier for camera manufacturers to design. The end result is that your photos will have fewer aberrations at smaller and smaller apertures.

How does this look in practice? See the photos below (heavy crops from the top-left corner):

What you're seeing above may look like an increase in sharpness, but it's really a decrease in aberrations. The end result? At f/5.6 on this particular lens, my photo is much sharper than at f/1.4.

Here's a key question: How does this balance out with diffraction, which harms sharpness increasingly more as your aperture gets narrower and narrower?

In practice, the answer is that most lenses end up sharpest around f/4, f/5.6, or f/8. Those "medium" apertures are small enough to block light from the edges of a lens, but they aren't so small that diffraction is a significant problem. However, you'll want to test this on your own equipment.

Of course, you can still take good photos at large apertures like f/1.4 or f/2. As I mentioned earlier, portrait photographers sometimes pay thousands of dollars to get a lens exactly for that purpose! So, don't lock your lens to f/5.6 just because it gives you a tad more corner sharpness up close. It's better to choose an aperture that gives you the right artistic look to the image.

Side Note

Some types of aberrations don't change much as you stop down, or they may even get slightly worse. Axial chromatic aberration, for example - color fringes near the edges of your frame - often work that way. This is normal. It happens because a small aperture doesn't inherently reduce aberrations; it simply blocks light that has passed through the edges of your lens. So, naturally, if the edges aren't the source of your problem, you won't see an improvement by stopping down.

3. Starburst and Sunstar Effects

Starbursts, also called sunstars, are beautiful elements that you'll find in certain photographs. Despite the odd names - one a type of candy; the other a type of starfish - I always try to capture them in my landscape photos. Here's an example:

How does this work? Essentially, for every aperture blade in your lens, you'll end up with a sunbeam. This only happens if you photograph a small, bright point of light, such as the sun when it is partly blocked. This is fairly common in landscape photography. If you want the strongest possible starburst, use a small aperture. Whenever the sun is in my photo, I almost always set f/16 purely to capture this effect.

Also, the starburst effect looks different from lens to lens. It all depends upon your aperture blades. If your lens has six aperture blades, you'll get six sunbeams. If your lens has eight aperture blades, you'll get eight sunbeams. And, if your lens has nine aperture blades, you'll get eighteen sunbeams.

Wait, what?

That's no typo. You always end up with an even number of sunbeams. If your lens has an odd number of aperture blades, you'll get double the number of sunbeams.

It sounds strange, but the reason is actually quite simple. In lenses with an even number of aperture blades (and a fully symmetrical design), half of the sunbeams will overlap the other half. So, you don't see all of them in your final photo.

Here's a diagram to show what I mean:

Most Nikon lenses have seven or nine aperture blades, resulting in 14 and 18 sunbeams respectively. Most Canon lenses have eight aperture blades, resulting in eight sunbeams. I took the photo above using the Nikon 20mm f/1.8G lens, which has 7 aperture blades. That's why the image has 14 sunbeams.

It's not just the number of blades that matters, though - their shape is also important. Some aperture blades are rounded (which results in a more pleasant out-of-focus background blur), and others are straight. If your goal is to capture good starbursts, straight aperture blades typically produce more defined rays of light.

Again, some lenses are better than others in this regard. For the best results, find a lens that's known to have good starbursts, and then set it to a small aperture like f/16. That's going to give you the strongest definition in your starbursts.

Finally, there's one last related effect that I wanted to mention briefly. When you shoot into the sun, you might end up with flare in your photographs, as shown below. Depending upon your chosen aperture, the size and shape of this lens flare may change slightly. This isn't a big deal, but it still exists.

4. Small Aperture and Unwanted Elements

When you shoot through things such as fences, dirty windows, plants, and even water droplets on your lens, you'll probably be disappointed by photos taken with a small aperture.

Small apertures like f/11 and f/16 give you such a large depth of field that you may accidentally include elements that you don't want to be in focus! For example, if you're shooting at a waterfall or by the ocean, an aperture of f/16 could render a tiny water droplet on your lens into a distinct, ugly blob:

In cases like that, it's better just to use a wider aperture - something like f/5.6, perhaps - in order to capture the water droplet so out-of-focus that it doesn't even appear in your image. In this particular case, you could simply wipe the droplet off, but that's not possible if you're shooting through something like a dirty window.

Side Note

You might have realized that this section is really just an extension of depth of field, and that's true! However, it's a bit of a special case, so I decided to mention it specifically.

Another example of shooting through things is when a piece of dust lands on your camera sensor. Unfortunately, as you change lenses, this is very common. Dust specks on your camera sensor will show up very clearly at small apertures like f/16, even if they're invisible at something larger, like f/4.

Luckily, they are very easy to remove in post-production software like Photoshop or Lightroom, though it can be annoying if you have to remove dozens of them from a single photo. That's why you should always keep your camera sensor clean.

5. Changes to Your Bokeh

What is bokeh? It's simply the quality of your background blur. If you take a lot of portraits, macro photos, or wildlife photos, you'll end up with out-of-focus backgrounds in most of your images. Naturally, you want them to look as good as possible! Different aperture settings will change the shape of your background blur.

Why is that? It's because the background blur of your photographs always takes on the shape of your aperture blades. So, if your aperture blades are shaped like a heart, you'll end up with heart-shaped background blur. Most of the time, that would qualify as distracting bokeh, although it's kind of cute in this photo of two fake tortoises:

On some lenses, aperture blades change shape a bit as they open and close. Large aperture settings (such as f/1.8) often have rounder background blur compared to smaller aperture settings. You'll also get more background blur at large apertures, since your depth of field is thinner.

If bokeh is something that matters to you, you'll want to test this on your particular lenses. Take some out-of-focus photos of a busy scene, each using a different aperture setting, and see which one looks the best. Most of the time, it will be the lens's widest aperture, but not always.

6. Focus Shift Issues

With certain lenses - even if you're in manual focus, and you don't move your focus ring - your point of focus may shift as you use smaller and smaller apertures.

Obviously, this isn't ideal. How do you tell if your lens has problematic focus shift? It's pretty easy. Here are the steps:

Put your camera on a tripod, and set your lens to manual focus.

Find an object with small details that extends backwards, and focus at the center of it. A table with a tablecloth works well.

Double check: When take a test photo and magnify it, you should see pixel-level details, as well as portions of the photo that are clearly out of focus.

Take a photo at your lens's widest aperture, and then at progressively smaller apertures. Be sure not to move your focus ring, and double check that you are using manual focus.

On your computer, zoom into 100% on these photos and see if the sharpest point of focus moves continuously farther back as you stop down. The more it moves, the worse your focus shift issue is.

You're done!

If your lens has extreme levels of focus shift, you'll want to compensate for it:

With your widest aperture, just focus like normal.

As you stop down the aperture, make sure to set your aperture first, then focus second (rather than focusing first). On DSLRs, we recommend focusing in live view at these apertures, because the viewfinder always focuses at the widest aperture. Mirrorless camera users don't need to worry about that.

With small apertures like f/8 and beyond, your depth of field will be large enough to hide any focus shift problems, so just focus like normal.

Side Note

When it comes down to it, focus shift is just another type of lens aberration. The edges of your lens may not focus light the same as the center, so, by stopping down - again, blocking light from the edges - your focus point changes slightly. That's the underlying reason for this effect.

7. Ease of Focusing

The autofocus system on your camera doesn't work well unless it receives plenty of light.

So, if you're shooting with a cheaper lens like a 70-300mm f/4.5-5.6, the largest aperture isn't bright enough to gather a lot of light. Focusing in dark conditions may be impacted. This is part of why a lot of pro photographers will use a more expensive lens like a 70-200mm f/2.8 instead.

You'll also enjoy a brighter viewfinder (on a DSLR) or a less noisy viewfinder (on a mirrorless camera) if your lens has a large maximum aperture. If you shoot a lot in low light, this can make it much easier to focus and compose your images.

8. Flash Exposure

When using speedlights or any kind of strobes, it is important to remember that aperture takes on a whole different role of controlling flash exposure. While shutter speed's role becomes controlling ambient light, aperture has an outsized impact on how much light from your flash is captured. Even though it's just a subset of exposure, we wanted to include it in this section, since flash is tightly correlated to lens aperture.

A Chart of Everything Aperture Does

Once you understand the information above, you will know everything aperture does to your photos. However, it may take a few re-reads of this article before it's all completely clear.

Practice is your best friend. Go outside, take some photos, and get a feel for aperture yourself.

If it helps, I compiled the main information in this article into a chart. This chart covers the most important effects of aperture in photography, as well as common terms that photographers use to describe their settings.

Note that to make this diagram easier to see, I did not darken or lighten any of the sample illustrations (as would occur in the real world). Instead, I simply wrote "brightest" through "darkest":

Although this chart is intentionally simplified, it covers all the basics that you need to know. Feel free to download and print this chart if you find it useful. Just right-click on the image, then select "save as," and pick the location where you want to store it.

Aperture FAQ

We put together some of the most frequently-asked questions related to aperture below.
How Does Aperture Affect Bokeh?
Bokeh refers to the quality of out-of-focus highlights of the image rendered by the camera lens. Using the maximum aperture of the lens will typically yield circular background highlights of large size, whereas stopping down the lens will typically result in highlights looking smaller and taking different shapes such as heptagon. These shapes depend on the number of aperture blades and their roundness. Here is an image of a 50mm f/1.4 prime lens stopped down to f/2.8 and f/4 apertures:

How Does Aperture Affect Sharpness?
Aperture is clearly a crucial setting in photography and it is possibly the single most important setting of all. Aperture affects several different parts of your photo, but you'll get the hang of everything fairly quickly. For a quick summary, a narrow aperture...

Makes your photos darker

Gives you more depth of field

Increases blur from diffraction

Decreases blur from most lens aberrations

Makes sensor dust more visible

Heightens the intensity of starbursts

...whereas a wide aperture does the opposite.

Soon, this won't be something that you even need to think about; you'll remember it all naturally. Personally, if I want a starburst effect in my photos, I immediately know to use an aperture of f/16. When I need as much light as possible, I set a larger aperture like f/2.8 or f/2 without a second thought. It doesn't take too much practice to get to that point.

With how important aperture is, it shouldn't be a surprise that, at Photography Life, we shoot in aperture-priority or manual mode all of the time. We simply never want the camera to select the aperture for us. It's just too important, and it is one of those basic settings that every beginner or advanced photographer needs to know in order to take the best possible images.

As always, it's best if you learn all this for yourself. Find something spectacular to capture, and put your new knowledge into practice. The more photos you take, the more you'll learn. Aperture is no exception.

Below are some other related posts you might enjoy:

Hopefully, you found that this article explains the basics of aperture in a way that is understandable and straightforward.

If you are ready to move on, the next important camera setting to learn is ISO, which we explain in Chapter 5 of our Photography Basics guide.

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What is Aperture? Understanding Aperture in Photography

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Aperture is one of the three pillars of photography, and certainly the most important. In this article, we go through everything you need to know about aperture and how it works.