Camera Obscura

Instrument invented ab. 1569 by Baptist a Porta of Naples. It consists of a dark room or box, into which rays of light from without are admitted through a very small opening. If a screen be placed in the chamber opposite the opening, inverted images of outside objects will be obtained on the screen in their natural colors, but reduced in size. It was soon found that a convex lens placed in such an opening produced a much sharper and, because of the much greater quantity of light admitted, much brighter image. The chief use of the camera at present is for photographic purposes, in which case the screen is replaced by a sensitive plate upon which the image is thrown.