The term "camera obscura" also refers to constructions or devices that make use of the principle within a box, tent or room. Camerae obscurae with a lens in the opening have been used since the second half of the 16th century and became popular as an aid for drawing and painting. The camera obscura box was developed further into the photographic camera in the first half of the 19th century when camera obscura boxes were used to expose light-sensitive materials to the projected image.

The camera obscura was used as a means to study eclipses, without the risk of damaging the eyes by looking into the sun directly. As a drawing aid, the camera obscura allowed tracing the projected image to produce a highly accurate representation, especially appreciated as an easy way to achieve a proper graphical perspective.

Before the term "camera obscura" was first used in 1604, many other expressions were used including "cubiculum obscurum", "cubiculum tenebricosum", "conclave obscurum" and "locus obscurus".

A camera obscura device without a lens but with a very small hole is sometimes referred to as a "pinhole camera", although this more often refers to simple (home-made) lens-less cameras in which photographic film or photographic paper is used.

Illustration of the principle of the camera obscura, 1671.© Photos.com/Jupiterimages

Children watching an outdoor scene through a camera obscura, 1887.© Photos.com/Thinkstock

drawing: Mechanical devices…apparatus, as well as the camera obscura (a darkened enclosure having an aperture usually provided with a lens through which light from external objects enters to form an image on the opposite surface), were frequently employed. In a darkened room the desired section is reflected through a lens onto a…

history of photography: Antecedents…of the camera was the camera obscura, a dark chamber or room with a hole (later a lens) in one wall, through which images of objects outside the room were projected on the opposite wall. The principle was probably known to the Chinese and to ancient Greeks such as Aristotle…

Johannes Vermeer: Working methods…to those seen in a camera obscura, a fascinating optical device that operates much like a box camera. The 17th-century camera obscura created an image by allowing light rays to enter a box through a small opening that was sometimes fitted with a focusing tube and lens. Because of the…

calotype…exposed to light in a camera obscura; those areas hit by light became dark in tone, yielding a negative image. The revolutionary aspect of the process lay in Talbot’s discovery of a chemical (gallic acid) that could be used to “develop” the image on the paper—i.e., accelerate the silver chloride’s…

Camera obscura is a very old device. Oldest mention of its effect is by Mozi, Chinese philosopher and the founder of Mohism, during the 5th century BC. He noticed that an image from camera obscura is flipped upside down and from left to right as a result of light’s moving in straight line. The Greek philosopher Aristotle noticed in 4th century that light from a sun eclipse that passes through holes between the leaves, projects an image of an eclipsed sun on the ground. Passing of light in the straight line also noticed Euclid 4th century BC and Theon of Alexandria in 4th century AD. Anthemius of Tralles, which designed the Hagia Sophia, used a type of camera obscura in his experiments in 6th century. Al-Kindi, Arab philosopher, mathematician, physician, and musician, performed experiments with light and a pinhole in 9th century and proved again behavior of light.

All these scientists experimented with a small hole and light but none of them suggested that a screen is used so an image from one side of a hole in surface could be projected at the screen on the other. First one to do so was Alhazen (also known as Ibn al-Haytham) in 11th century. He was a scientist, mathematician, astronomer and philosopher, he wrote the Book of Optics and, among other things, he invented camera obscura and pinhole camera. At about the same time, Chinese scientist Shen Kuo experimented with a camera obscura. He described it geometrically and even used it explain some effects that were mentioned couple centuries ago but were attributed to the geographic characteristics of the area. As described by Roger Bacon, English philosopher, camera obscura was used in 13th century for safe observation of sun eclipse. Arnaldus de Villa Nova, an alchemist, astrologer and physician, used camera obscura at the same time as a projector for entertainment. Artists started using camera obscura in 15th century. Leonardo da Vinci talks about camera obscura in his “Codex Atlanticus”, a twelve-volume bound set of his drawings and writings where he also talked about flying machines, weaponry and musical instruments. Giambattista della Porta, Italian scholar, improved camera obscura by adding it a lens at the place where light enters the box. He also used camera obscura to explain how human eye works. German astronomer Johannes Kepler uses term “camera obscura” for the first time in history in 1604. Johann Zahn, writer of "Oculus Artificialis Teledioptricus Sive Telescopium”, writes in his book in 17th century about camera obscura and magic lantern among other optical instruments. In 18th century Conte Francesco Algarotti writes his book “Saggio sopra Pittura” and dedicates a whole chapter to the use of camera obcura (or how he calls it “camera ottica” ("optic chamber")) in painting.

Early models were large and consisted of a literal room or a tent (Johannes Kepler used a tent one.) Later more portable variants were invented. They were wooden boxes that had a lens instead of pinhole which can be moved to provide a focus. They also had a mirror that rotated image and a screen onto which an image was projected. These cameras were basis for early photographic cameras.