Folding tent-type camera obscura, 1800-1824.
© Science Museum / Science & Society Picture Library
A folding tent-type camera obscura made during the early 19th century. It consists of an adjustable right-angle mirror held in a framework that rotates vertically aloft a tent-like structure. Within the darkened confines of the contrivance, the artist is able to outline in pencil the picture projected onto their paper by the instrument's optics. Camera obscuras were known to the ancient Greeks, Chinese and were used by Arab astronomers in the 10th century to observe the Sun. During the Renaisance period artists used camera obscuras to help them to draw more accurately.