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Principle of camera obscura: light rays from an object pass through a small hole to form an inverted image.
An image of the New Royal Palace at Prague Castle projected onto an attic wall by a hole in the tile roofing.

Camera obscura (Latin for "dark room"), sometimes referred to as "pinhole image", is the natural optical phenomenon that occurs when an image of a scene at the other side of a screen (or for instance a wall) is projected through a small hole in that screen as an inverted image (left to right and upside down) on a surface opposite to the opening. The surroundings of the projected image have to be relatively dark for the image to be clear, so many historical experiments were done in literally dark rooms.

The term "camera obscura" also refers to constructions or devices that make use of the principle within a box, tent or a 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 device was developed further into the photographic camera early in the 19th century.

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

Physical explanation

Rays of light travel in straight lines and change when they are reflected and partly absorbed by an object, retaining information about the color and brightness of the surface of that object. Lit objects reflect rays of light in all directions. A small enough opening in a screen only lets through rays that travel directly from different points in the scene on the other side and together form an image of that scene when they are reflected on a surface into the eye of an observer. The human eye itself works much like a camera obscura with an opening (pupil), a biconvex lens and a surface where the image is formed (retina}).


A diagram of a camera obscura with an upright projected image at the top.

A camera obscura device consists of a box, tent or room with a small hole in one side. Light from an external scene passes through the hole and strikes a surface inside, where the scene is reproduced, inverted (thus upside-down), but with color and perspective preserved. In a room or tent the image can be projected onto paper, and can then be traced to produce a highly accurate representation.

In order to produce a reasonably clear projected image, the aperture has to be about 1/100th the distance to the screen, or less.

Many 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.

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.

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.


30.000 BCE to 500 BCE: Possible inspiration for prehistoric art and possible use in religious ceremonies

There are theories that occurrences of camera obscura effects (through tiny holes in tents or in screens of animal hide) inspired paleolithic cave paintings. Distortions in the shapes of animals in many paleolithic cave artworks might be inspired by distortions seen when the surface on which the image is projected is not straight or not in the right angle.[1] It is also suggested that camera obscura projections could have played a role in Neolithic structures.[2][3] Some ancient sightings of gods or spirits in temples are thought to possibly have been conjured up by means of camera obscura projections.[4][5]

500 BCE to 500 CE: Earliest written observations

Holes in the leaf canopy project images of a solar eclipse on the ground.

The earliest extant written record of the camera obscura is to be found in the writings of Mozi (circa 470 BCE-circa 391 BCE), a Han Chinese philosopher and the founder of Mohist School of Logic. Mozi correctly asserted that the camera obscura image is flipped upside down because light travels in straight lines from its source. His disciples developed this into a physics theory of optics.[6][note 1]

The Greek philosopher Aristotle (384-322 BCE), or possibly a follower of his ideas, touched upon the subject in the work Problems - Book XV, asking:

"Why is it that when the sun passes through quadri-laterals, as for instance in wickerwork, it does not produce a figure rectangular in shape but circular?”

and further on:

“Why is it that an eclipse of the sun, if one looks at it through a sieve or through leaves, such as a plane-tree or other broadleaved tree, or if one joins the fingers of one hand over the fingers of the other, the rays are crescent-shaped where they reach the earth? Is it for the same reason as that when light shines through a rectangular peep-hole, it appears circular in the form of a cone?"

Aristotle never found an answer. The mystery was resolved centuries later, when it was concluded that the circular shapes on the ground were camera obscura projections of the sun and thus became crescent-shaped during an eclipse.

Euclid is sometimes reported to have mentioned the camera obscura phenomenon as a demonstration that light travels in straight lines in his very influential Optics (circa 300 BCE).[7] However, in common translations[8] no remarks of anything that resembles camera obscura can be found. Claims could be based on later versions, since Ignazio Danti added a description of camera obscura in his 1573 annotated translation.[9]

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."

500 to 1300: Experiments, study of light, entertainment

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.[10]

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."

In the 10th century Yu Chao-Lung supposedly projected images of pagoda models through a small hole onto a screen to study directions and divergence of rays of light.[11]

Arab physicist Ibn al-Haytham (known in the West by the latinised Alhazen) (965–1039) explained in his Book of Optics (circa 1027) that rays of light travel in straight lines and are distinguished by the body that reflected the rays and then wrote:

"Evidence that light and color do not mingle in air or (other) transparent bodies is (found in) the fact that, when several candles are at various distinct locations in the same area, and when they all face a window that opens into a dark recess, and when there is a white wall or (other white) opaque body in the dark recess facing that window, the (individual) lights of those candles appear individually upon that body or wall according to the number of those candles; and each of those lights (spots of light) appears directly opposite one (particular) candle along a straight line passing through that window. Moreover, if one candle is shielded, only the light opposite that candle is extinguished, but if the shielding object is lifted, the light will return."[12]:91#5:p379[6.85],[6.86]

Al-Haytam's observations of light's behaviour through a pinhole

In his 1038 essay "On the form of the Eclipse" (Maqalah-fi-Surat-al-Kosuf) (Arabic: مقالة في صورةالكسوف) he wrote:

"The image of the sun at the time of the eclipse, unless it is total, demonstrates that when its light passes through a narrow, round hole and is cast on a plane opposite to the hole it takes on the form of a moon-sickle. The image of the sun shows this peculiarity only when the hole is very small. When the hole is enlarged, the picture changes, and the change increases with the added width. When the aperture is very wide, the sickle-form image will disappear, and the light will appear round when the hole is round, square if the hole is square, and if the shape of the opening is irregular, the light on the wall will take on this shape, provided that the hole is wide and the plane on which it is thrown is parallel to it."[13]

Al-Haytham also analyzed the rays of sunlight and concluded that they make a conic shape where they meet at the hole, forming another conic shape reverse to the first one from the hole to the opposite wall in the dark room (see illustration). Ibn al-Haytham is reported to have stated about the camera obscura: "We did not invent this".[14] al-Haytam's writings on optics became very influential in Europe through Latin translations since circa 1200. Among the people who he inspired were Witelo, John Peckham, Roger Bacon, Leonardo Da Vinci, René Descartes and Johannes Kepler.[15]

In his 1088 book Dream Pool Essays the Song Dynasty Chinese scientist Shen Kuo (1031–1095) compared the focal point of a concave burning-mirror and the "collecting" hole of camera obscura phenomena to an oar in a rowlock to explain how the images were inverted:

"When a bird flies in the air, its shadow moves along the ground in the same direction. But if its image is collected (shu)(like a belt being tightened) through a small hole in a window, then the shadow moves in the direction opposite of that of the bird.[...] This is the same principle as the burning-mirror. Such a mirror has a concave surface, and reflects a finger to give an upright image if the object is very near, but if the finger moves farther and farther away it reaches a point where the image disappears and after that the image appears inverted. Thus the point where the image disappears is like the pinhole of the window. So also the oar is fixed at the rowlock somewhere at its middle part, constituting, when it is moved, a sort of 'waist' and the handle of the oar is always in the position inverse to the end (which is in the water)."

Shen Kuo also responded to a statement of Duan Chengshi in Miscellaneous Morsels from Youyang written in about 840 that the inverted image of a Chinese pagoda tower beside a seashore, was inverted because it was reflected by the sea: "This is nonsense. It is a normal principle that the image is inverted after passing through the small hole."[16]

English statesman and scholastic philosopher Robert Grosseteste (c. 1175 – 9 October 1253) commented on the camera obscura.[17]

Three-tiered camera obscura, 13th century (attributed to Roger Bacon)

English philosopher and Franciscan friar Roger Bacon (c. 1219/20 – c. 1292) tried to answer Aristotle's question (see above).[18] Bacon wrote about optics in his work Opus Majus Part five De Scientia Perspectivae (1267) for which he seems to have studied the writings of Al-Kindi and Al-Haytam. Bacon is sometimes thought to have used a camera obscura projection in combination with mirrors, based on a passage in his book which says (translated from Latin):

"Mirrors may be so arranged that we may see whatever we choose and anything in the house or in the street, and everyone looking at those things will see them as if they were real, but when they go to the spot they will find nothing. For the mirrors can be hidden from things in such a way that the images will be in the open and will appear in the air at the intersection of the visual rays and the catheti (perpendicular plane), and therefore those looking at them would run up to the places where they appear and would judge that the objects are there when there is in reality nothing except an image."

Others point out this contains no evidence of camera obscura and think this possibly alludes to projection with concave mirrors.[18]

A picture of a three-tiered camera obscura (see illustration) is attributed to Bacon, but its origins are not further defined.[19]

At the end of the 13th century, Arnaldus de Villa Nova is credited with using a camera obscura to project live performances for entertainment.[20][21]

1450 to 1600: Drawings, lenses

Da Vinci's drawings comparing the eye to a camera obscura from Codex Atlanticus (1490-1495)

Italian polymath Leonardo da Vinci (1452–1519), familiar with the work of Alhazen in Latin translation and after an extensive study of optics and human vision, wrote the oldest known clear description of the camera obscura in mirror writing in a notebook in 1502, later published in the collection Codex Atlanticus:

"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."[22]

These descriptions, however, would remain unknown until Venturi deciphered and published them in 1797.[23] Da Vinci also drew 270 diagrams of the camera obscura in his notebooks.[24]

The camera obscura's potential as a drawing aid may have been familiar to artists by as early as the 15th century.

First published picture of camera obscura in Gemma Frisius' 1545 book De Radio Astronomica et Geometrica

The oldest known published drawing of a camera obscura is found in Dutch physician, mathematician and instrument maker Gemma Frisius’ 1545 book De Radio Astronomica et Geometrica, in which he described and illustrated how he used the camera obscura to study the solar eclipse of January 24, 1544[23]

Italian polymath Gerolamo Cardano described using a biconvex lens in a camera obscura in his 1550 book De subtilitate, vol. I, Libri I-VII,[25]

Italian polymath Giambattista della Porta described a camera obscura in the 1558 first edition of his book series Magia Naturalis. He suggests to use a convex mirror to project the image upright and to use this as a drawing aid.[26] The popularity of his books helped spread knowledge of the camera obscura.

In his 1567 work La Pratica della Perspettiva Venetian nobleman Daniello Barbaro (1513-1570) described using a camera obscura with a biconvex lens as a drawing aid.[25]

Giambattista della Porta added a “lenticular crystal” or biconvex lens to the camera obscura description in the 1589 second edition of Magia Naturalis.[26][27] As a playwright he also used the camera obscura to project "hunting, battles of enemies and other delusions" from an outside stage into a dark room with spectators.[28] Della Porta 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.

in 1585 Venetian mathematician Giambattista Benedetti proposed to use a mirror in a 45 degree angle to project the image upright. This leaves the image reversed, but would become common practice in later camera obscura boxes.[25]

1600 to 1800: Name coined, portable drawing aid in tents and boxes

The German astronomer Johannes Kepler coined the term "camera obscura" in his Paralipomena in 1604.[29] The term is based on the Latin camera, "(vaulted) chamber or room", and obscura, "darkened" (plural: camerae obscurae).

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 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.

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. A hand-held device with a mirror reflex mechanism was first proposed by Johann Zahn in 1685, a design that would later be used in photographic cameras.[30]

The scientist Robert Hooke presented a paper in 1694 to the Royal Society, in which he described a portable camera obscura. It was a cone-shaped box which fit onto the head and shoulders of its user.[31]

One chapter in the Conte Algarotti's Saggio sopra Pittura (1764) is dedicated to the use of a camera ottica ("optic chamber") in painting.[32]

By the 18th century, following developments by Robert Boyle and Robert Hooke, more easily portable models in boxes 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.

Role in the modern age

Camera obscuras for Daguerreotype called "Grand Photographe" produced by Charles Chevalier (Musée des Arts et Métiers).

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.[33] Western artists and philosophers used the Arab findings in new frameworks of epistemic relevance.[34] 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.[35] The modern use of the camera obscura as an epistemic machine had important side effects for science.[36][37]


Public access

Camera obscuras open to the public
Name City or Town Country Comment WWW Links
Astronomy Centre Todmorden England 80 inches (200 cm) table, 40° field of view, horizontal rotation 360°, vertical adjustment ±15° Equipment on site#Camera obscura
Bristol Observatory Bristol England View of Clifton Suspension Bridge Clifton Observatory
Constitution Hill Aberystwyth Wales 14 inches (360 mm) lens, which is claimed to be the largest in the world Cliff Railway and Camera Obscura, Aberystwyth
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
Camera Obscura and museum "Prehistory of Film" Mülheim Germany Claimed to be the biggest “walk-in” Camera Obscura in the world. Installed in Broich Watertower in 1992
Dumfries Museum Dumfries 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 United States 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 United States 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 United States In Mitchell Park overlooking the Peconic Bay and Shelter Island, New York. Built in 2004. Long Island Camera Obscura
Griffith Observatory Los Angeles, California United States Slowly rotates and gives a panoramic view of the Los Angeles Basin. Griffith Park Camera Obscura
The Exploratorium's Bay Observatory Terrace San Francisco, California United States Offers a view of San Francisco Bay, Treasure Island, and the Bay Bridge [1]

See also


  1. ^ In the Mozi passage, a camera obscura is described as a "collecting-point" or "treasure house" (); the 18th century scholar Bi Yuan (畢沅) suggested this was a misprint for "screen" ().


  1. ^
  2. ^
  3. ^
  4. ^
  5. ^ Needham, Joseph. Science and Civilization in China, vol. IV, part 1: Physics and Physical Technology (PDF). pp. 122–124. 
  6. ^ Needham 1986, 82.
  7. ^ Ben-Menahem. Historical Encyclopedia of Natural and Mathematical Sciences, Volume 1. p. 465. 
  8. ^ Optics of Euclid (PDF). 
  9. ^ "Kleine Geschichte der Lochkamera oder Camera Obscura" (in German). 
  10. ^ G. Huxley (1959) Anthemius of Tralles: a study of later Greek Geometry pp.6-8,pp.44-46 as cited in (Crombie 1990), p.205
  11. ^ Hammond, John H. (1981). The camera obscura: a chronicle. p. 2. 
  12. ^ * Smith, A. Mark, ed. and trans. (2001) Alhacen's Theory of visual perception : a critical edition, with English translation and commentary, of the first three books of Alhacen's De aspectibus, [the medieval latin version of Ibn al-Haytham's Kitāb al-Manāẓir], Transactions of the American Philosophical Society, 2 vols: 91(#4 — Vol 1 Commentary and Latin text); 91(#5 — Vol 2 English translation). (Philadelphia: American Philosophical Society), 2001. Books I-III (2001) Vol 1 Commentary and Latin text via JSTOR; Vol 2 English translation, Notes, Bibl. via JSTOR
  13. ^ Eder, JOSEF MARIA (1945). HISTORY OF PHOTOGRAPHY. p. 37. 
  14. ^ Adventures in CyberSound: The Camera Obscura
  15. ^ Plott, John C. (1984). Global History of Philosophy: The Period of scholasticism (part one). p. 460. 
  16. ^ Needham, Joseph (1986). Science and Civilization in China: Volume 4, Physics and Physical Technology, Part 1, Physics (PDF). Taipei: Caves Books Ltd. pp. 97–98. 
  17. ^ A reconsideration of Roger Bacon's theory of pinhole images
  18. ^ a b
  19. ^ Doble, Rick (2012). 15 Years of Essay-Blogs About Contemporary Art & Digital Photography. 
  20. ^ Burns, Paul T. "The History of the Discovery of Cinematography". Archived from the original on 2013-12-31. Retrieved 2014-01-04. 
  21. ^ Smith, Roger. "A Look Into Camera Obscuras". Retrieved 2014-10-23. 
  22. ^ Josef Maria Eder History of Photography translated by Edward Epstean Hon. F.R.P.S Copyright Columbia University Press
  23. ^ a b Grepstad, Jon. "Pinhole Photography – History, Images, Cameras, Formulas". 
  24. ^
  25. ^ a b c Ilardi, Vincent (2007). Renaissance Vision from Spectacles to Telescopes. pp. 220–221. 
  26. ^ a b Larsen, Kenneth. "Sonnet 24". 
  27. ^
  28. ^ Durbin, P.T. (2012). Philosophy of Technology. p. 74. 
  29. ^ Dupre, Sven (2008). "Inside the "Camera Obscura": Kepler's Experiment and Theory of Optical Imagery" (PDF). Early Science and Medicin. 13 (3): 219–244. 
  30. ^ Gernsheim, pp. 5-6
  31. ^ Wenczel, pg. 15
  32. ^ Algarotti, Francesco (1764). Presso Marco Coltellini, Livorno, ed. Saggio sopra la pittura. pp. 59–63. 
  33. ^ Hans Belting Das echte Bild. Bildfragen als Glaubensfragen. München 2005, ISBN 3-406-53460-0
  34. ^ An Anthropological Trompe L'Oeil for a Common World: An Essay on the Economy of Knowledge, Alberto Corsin Jimenez, Berghahn Books, 15.06.2013
  35. ^ Philosophy of Technology: Practical, Historical and Other Dimensions P.T. Durbin Springer Science & Business Media
  36. ^ Contesting Visibility: Photographic Practices on the East African Coast Heike Behrend transcript, 2014
  37. ^ Don Ihde Art Precedes Science: or Did the Camera Obscura Invent Modern Science? In Instruments in Art and Science: On the Architectonics of Cultural Boundaries in the 17th Century Helmar Schramm, Ludger Schwarte, Jan Lazardzig, Walter de Gruyter, 2008


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Chart showing the number of references in each month of the diary’s entries.