Advertisement for 'Photogenic Portraits' made using a camera obscura on sale for the price of four shillings and sixpence (£0.22.5p). The letterpres page is thought to have come from a bound prospectus. The camera obscura in its many forms projected an image of a scene onto a glas screen using lenses and mirrors or prisms. It was known to the ancient Greeks and Chinese, and was in use 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.
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