ArtistsÕ Aids, Camera Obscuras StorerÕs ÔRoyal DelineatorÕ camera obscura, 1778

ArtistsÕ Aids, Camera Obscuras StorerÕs ÔRoyal DelineatorÕ camera obscura, 1778. William StorerÕs ÔRoyal DelineatorÕ, an advanced form of camera obscura which was granted a British patent (No 1183). The superior design of the instrument uses a pair of rectilinear front lenses, a reflex mirror and third lens to give a bright overall image on its glass drawing screen. In operation, a picture was formed from the lenses that was reflected off a mirror onto a glass screen from beneath. The artist was thus able to lightly outline the projected picture using a soft pencil. Camera obscuras were known to the ancient Greeks and Chinese and were used by Arab astronomers in the 10th century to observe the Sun. ©SSPL/Science Museum