camera obscura

camera obscura (Latin: ‘dark chamber’). An apparatus that projects the image of an object or scene onto a sheet of paper or other surface so that the outlines can be traced. It consists of a shuttered box or space with a small hole or lens in one side through which light from a brightly lit scene enters and forms an inverted image on a screen placed opposite the opening. The optical principle is essentially that of the photographic camera. For greater convenience a mirror is sometimes installed, reflecting the image the right way up onto a suitably placed drawing surface. The principle was known as early as Aristotle, but the first account of its use for drawing was published in 1558, in Magia naturalis (1558), a scientific book by Giambattista della Porta, an Italian physician. Various 17th-century painters are known or thought to have used a camera obscura in their work, and by the 18th century it had become a craze. Both amateurs and professionals—among them Canaletto—used it for topographical painting, and there are accounts of an apparatus, somewhat like a sedan chair, inside which an artist could sit and draw, at the same time actuating bellows with his feet to improve the ventilation. More modest versions were easily portable and even pocketable. See also Hockney and Vermeer.