Folding wooden camera obscura, early 19th century.

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 internal 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 Renaisance period, artists used camera obscuras to help them to draw more accurately. Rear view.