Talbot�s camera obscura, c 1820.

UNITED KINGDOM - AUGUST 22: A replica of a wooden box camera obscura belonging to the photography pioneer William Henry Fox Talbot (1800-1877), made by the Science Museum, London. This camera obscura has a frame designed to hold tissue paper for copying views by hand. A camera obscura is a box or darkened room with a lens or hole, through which an image of an external object is projected onto the opposite inside wall. Camera obscuras were known to the ancient Greeks and Chinese, and were used by Arab astronomers in the 10th century to observe the Sun. During the Renaissance period, artists used camera obscuras to help them to draw more accurately. (Photo by SSPL/Getty Images)