"Camera obscura: Storer's Royal delineator, c 1780."
© Science Museum / Science & Society Picture Library
"A camera obscura is a box or darkened room with a lens or hole through which the image of an external object is projected onto the opposite internal wall. Camera obscuras were known to the ancient Chinese and Greeks, and used by Arab astronomers in the 10th century to observe the sun. During the Renaissance, artists used camera obscuras to help them draw more accurately."