Sir Joshua Reynolds' camera obscura, c 1760-1780.
© Science Museum / Science & Society Picture Library
This view shows an early form of camera obscura, dismantled and folded flat in the form of a book. Owned by Sir Joshua Reynolds, the famous English portrait painter, it is fitted with a mirror and lens. This allows an image to be projected onto a piece of paper inside the darkened box that can then be traced out. 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.