Camera obscura

This article is about an optical device. For other uses, see Camera obscura (disambiguation).

A drawing of a camera obscura

Camerae obscurae for Daguerreotype called "Grand Photographe" produced by Charles Chevalier (Musée des Arts et Métiers)

An image of the New Royal Palace at Prague Castle projected onto an attic wall by a hole in the tile roofing

A camera obscura (Latin for "dark room") is an optical device that led to photography and the photographic camera. The device consists of a box or room with a hole in one side. Light from an external scene passes through the hole and strikes a surface inside, where it is reproduced, inverted (thus upside-down), but with color and perspective preserved. The image can be projected onto paper, and can then be traced to produce a highly accurate representation. The largest camera obscura in the world is on Constitution Hill in Aberystwyth, Wales.

Using mirrors, as in an 18th-century overhead version, it is possible to project a right-side-up image. Another more portable type is a box with an angled mirror projecting onto tracing paper placed on the glass top, the image being upright as viewed from the back.

As the pinhole is made smaller, the image gets sharper, but the projected image becomes dimmer. With too small a pinhole, however, the sharpness worsens, due to diffraction. In practice, most camerae obscurae use a lens rather than a pinhole (as in a pinhole camera) because it allows a larger aperture, giving a usable brightness while maintaining focus.

Role in the modern age

While the technical principles of the camera obscura have been known since antiquity, the broad use of the technical concept in producing images with a linear perspective in paintings, maps, theatre setups and architectural and later photographic images and movies started in the Western Renaissance and the scientific revolution. While e.g. Alhazen (Ibn al-Haytham) had already observed an optical effect and developed a state of the art theory of the refraction of light, he was less interested to produce images with it (compare Hans Belting 2005); the society he lived in was even hostile (compare Aniconism in Islam) towards personal images. Western artists and philosophers used the Arab findings in new frameworks of epistemic relevance. E.g. Leonardo da Vinci used the camera obscura as a model of the eye, René Descartes for eye and mind and John Locke started to use the camera obscura as a metaphor of human understanding per se. The modern use of the camera obscura as an epistemic machine had important side effects for science.

History

Further information: Mathematics and art

Camera obscura in Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers. 18th century

The earliest extant written record of the camera obscura is to be found in the writings of Mozi (470 to 390 BC), a Chinese philosopher and the founder of Mohism. Mozi correctly asserted that the image in a camera obscura is flipped upside down because light travels in straight lines from its source. His disciples developed this into a minor theory of optics.

The Greek philosopher Aristotle (384 to 322 BC) was familiar with the principle of the camera obscura. He viewed the crescent shape of a partially eclipsed sun projected on the ground through the holes in a sieve and through the gaps between the leaves of a plane tree. In the 4th century BC, Aristotle noted that "sunlight travelling through small openings between the leaves of a tree, the holes of a sieve, the openings wickerwork, and even interlaced fingers will create circular patches of light on the ground." Euclid's Optics (c. 300 BC) mentioned the camera obscura as a demonstration that light travels in straight lines. In the 4th century, Greek scholar Theon of Alexandria observed that "candlelight passing through a pinhole will create an illuminated spot on a screen that is directly in line with the aperture and the center of the candle."

In the 6th century, the Byzantine-Greek mathematician and architect Anthemius of Tralles (most famous for designing the Hagia Sophia), used a type of camera obscura in his experiments.

In the 9th century, Al-Kindi (Alkindus) demonstrated that "light from the right side of the flame will pass through the aperture and end up on the left side of the screen, while light from the left side of the flame will pass through the aperture and end up on the right side of the screen."

Then Ibn al-Haytham (AD 965–1039), also known as Alhazen, described a 'dark room' and experimented with images seen through the pinhole. He arranged three candles in a row and put a screen with a small hole between the candles and the wall. He noted that images were formed only by means of small holes and that the candle to the right made an image to the left on the wall.

Leonardo da Vinci (1452–1519), familiar with the work of Alhazen in Latin translation and after an extensive study of optics and human vision, published the first clear description of the camera obscura in Codex Atlanticus (1502):

If the facade of a building, or a place, or a landscape is illuminated by the sun and a small hole is drilled in the wall of a room in a building facing this, which is not directly lighted by the sun, then all objects illuminated by the sun will send their images through this aperture and will appear, upside down, on the wall facing the hole. You will catch these pictures on a piece of white paper, which placed vertically in the room not far from that opening, and you will see all the above-mentioned objects on this paper in their natural shapes or colors, but they will appear smaller and upside down, on account of crossing of the rays at that aperture. If these pictures originate from a place which is illuminated by the sun, they will appear colored on the paper exactly as they are. The paper should be very thin and must be viewed from the back.

The Song Dynasty Chinese scientist Shen Kuo (1031–1095) experimented with a camera obscura, and was the first to apply geometrical and quantitative attributes to it in his book of 1088 AD, the Dream Pool Essays. However, Shen Kuo alluded to the fact that the Miscellaneous Morsels from Youyang written in about 840 AD by Duan Chengshi (d. 863) during the Tang Dynasty (618–907) mentioned inverting the image of a Chinese pagoda tower beside a seashore. In fact, Shen makes no assertion that he was the first to experiment with such a device. Shen wrote of Cheng's book: "[Miscellaneous Morsels from Youyang] said that the image of the pagoda is inverted because it is beside the sea, and that the sea has that effect. This is nonsense. It is a normal principle that the image is inverted after passing through the small hole."

In 13th-century England, Roger Bacon described the use of a camera obscura for the safe observation of solar eclipses. At the end of the 13th century, Arnaldus de Villa Nova is credited with using a camera obscura to project live performances for entertainment. Its potential as a drawing aid may have been familiar to artists by as early as the 15th century; Leonardo da Vinci (1452–1519 AD) described the camera obscura in Codex Atlanticus. Johann Zahn's Oculus Artificialis Teledioptricus Sive Telescopium, published in 1685, contains many descriptions, diagrams, illustrations and sketches of both the camera obscura and the magic lantern.

Camera obscura, from a manuscript of military designs. 17th century, possibly Italian

Giambattista della Porta improved the camera obscura by replacing the hole with an old man's lenticular (biconvex) lens in his Magia Naturalis (1558-1589), the popularity of which helped spread knowledge of it. He compared the shape of the human eye to the lens in his camera obscura, and provided a readily comprehensible example of how light forms images in the eye. One chapter in the Conte Algarotti's Saggio sopra Pittura (1764) is dedicated to the use of a camera ottica ("optic chamber") in painting.

The 17th century Dutch Masters, such as Johannes Vermeer, were known for their magnificent attention to detail. It has been widely speculated that they made use of such a camera, but the extent of their use by artists at this period remains a matter of considerable controversy, recently revived by the Hockney–Falco thesis.

Four drawings by Canaletto, representing Campo San Giovanni e Paolo in Venice, obtained with a camera obscura (Venice, Gallerie dell'Accademia)

The German astronomer Johannes Kepler described the use of a camera obscura in his Paralipomena in 1604. The term is based on the Latin camera, "(vaulted) chamber or room", and obscura, "darkened" (plural: camerae obscurae). The English physician and author Sir Thomas Browne speculated upon the interrelated workings of optics and the camera obscura in his 1658 discourse The Garden of Cyrus thus:

For at the eye the Pyramidal rayes from the object, receive a decussation, and so strike a second base upon the Retina or hinder coat, the proper organ of Vision; wherein the pictures from objects are represented, answerable to the paper, or wall in the dark chamber; after the decussation of the rayes at the hole of the hornycoat, and their refraction upon the Christalline humour, answering the foramen of the window, and the convex or burning-glasses, which refract the rayes that enter it.

Early models were large, comprising either a whole darkened room or a tent (as employed by Johannes Kepler). By the 18th century, following developments by Robert Boyle and Robert Hooke, more easily portable models became available. These were extensively used by amateur artists while on their travels, but they were also employed by professionals, including Paul Sandby, Canaletto and Joshua Reynolds, whose camera (disguised as a book) is now in the Science Museum in London. Such cameras were later adapted by Joseph Nicephore Niepce, Louis Daguerre and William Fox Talbot for creating the first photographs.

Examples

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  A freestanding room-sized camera obscura at the University of North Carolina at Chapel Hill. A pinhole can be seen to the left of the door.

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  A freestanding room-sized camera obscura in the shape of a camera. Cliff House, San Francisco

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  Image of the South Downs of Sussex in the camera obscura of Foredown Tower, Portslade, England

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  A camera obscura created by Mark Ellis in the style of an Adirondack mountain cabin, Lake Flower, Saranac Lake, NY

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  A 19th-century artist using a camera obscura to outline his subject

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  A modern-day camera obscura

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  A modern-day camera obscura used indoors

Public access

Camerae obscurae open to the public

Name	City	Country	Comment	WWW Links
Bristol Observatory	Bristol	England	View of Clifton Suspension Bridge	Clifton Observatory
Camera Obscura, and World of Illusions	Edinburgh	Scotland	Top of Royal Mile, just below Edinburgh Castle. Fine views of the city	Edinburgh's Camera Obscura
Dumfries Museum	Dumfries & Galloway	Scotland	In Dumfries Castle. Claims to be oldest working example in the world	Dumfries Museum
Grand Union Camera Obscura	Douglas	Isle of Man	On Douglas Head. Unique Victorian tourist attraction with eleven lenses	Visit Isle of Man
Camera Obscura (Giant Camera)	Golden Gate National Recreation Area, San Francisco, California	America	Adjacent to the Cliff House below Sutro Heights Park, with views of the Pacific Ocean. In the Sutro Historic District, and on the National Register of Historic Places.	Giant Camera
Santa Monica Camera Obscura	Santa Monica, California	America	In Palisades Park overlooking Santa Monica Beach, Santa Monica Pier, and the Pacific Ocean. Built in 1898.	Atlas Obscura
Long Island's Camera Obscura	Greenport, Suffolk County, New York	America	In Mitchell Park overlooking the Peconic Bay and Shelter Island, New York. Built in 2004.	Long Island Camera Obscura
Marineland	Napier	New Zealand	Part of the now closed Marine Land	-

See also

• Addicted to Love - 1997 American film in which a camera obscura plays a prominent role
• Black mirror
• Bristol Observatory
• Camera
• Camera lucida
• History of cinema
• Hockney–Falco thesis
• Magic lantern
• Optics
• Pepper's ghost

Sources

• Hill, Donald R. (1993), "Islamic Science and Engineering", Edinburgh University Press, page 70.
• Lindberg, D.C. (1976), "Theories of Vision from Al Kindi to Kepler", The University of Chicago Press, Chicago and London.
• Nazeef, Mustapha (1940), "Ibn Al-Haitham As a Naturalist Scientist", (Arabic), published proceedings of the Memorial Gathering of Al-Hacan Ibn Al-Haitham, 21 December 1939, Egypt Printing.
• Needham, Joseph (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 1, Physics. Taipei: Caves Books Ltd.
• Omar, S.B. (1977). "Ibn al-Haitham's Optics", Bibliotheca Islamica, Chicago.