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Dead medium: The Camera Obscura (Part Three)
From: kadrey@well.com (Richard Kadrey)

Source(s): Jones Telecommunications and Multimedia Encyclopedia, http://www.digitalcentury.com/encyclo/update/photo_hd.html

"The Camera Obscura

"In 1038 AD, an Arab scholar named Alhazan described a working model of the camera obscura. Literally meaning dark chamber, the camera obscura was a room or box lit only by a small hole that admitted sunshine. Light rays poured through the hole, eerily assembling an image of the outside world on the opposite wall.

"Although Alhazan did not actually construct the device, his work would influence a medieval tinkerer named Roger Bacon. In 1267 AD, Bacon created convincing optical illusions by using mirrors and the basic principles of the camera obscura. Later, he used a camera obscura to project an image of the sun directly upon an opposite wall.

(...)

"It was not until the Renaissance that the instrument was widely used as a drawing tool. Although Leonardo Da Vinci is popularly credited for using the camera obscura to draw, that is only partially true. A student of physiology, Da Vinci built a small camera obscura to test his theories about the workings of the human eye and the concept of perspective. Da Vinci never used the camera obscura to draw. Without a lens, the camera was not a very effective or portable tool for viewing the world.

"The introduction of the orbem e vitro, a kind of primitive biconvex lens, revolutionized the utility of the camera obscura. Like the lens that C.C. Harrison and J. Schinitzler would perfect in 1860, the orbem was constructed of two convex lenses. The design reduced distortion and increased clarity. Although no inventor is known, the lens was first mentioned by Girolamo Cardano, a Milanese mathematics professor, in the 1550 edition of his scientific encyclopedia.

"In 1558 the Neapolitan scientist Giovanni Battista della Porta suggested the camera obscura would make a wondrous aid to artists. In his *Magiae naturalis,* he discussed the applications to portraiture, landscapes, and the copying of other paintings. With the lens, he wrote, 'You will see everything clearer, the faces of men walking in the street, the colors, clothes, and everything as if you stood nearby.'

Richard Kadrey (kadrey@well.com)