The first version of a stable photograph with an exposure ranging from 8 hours to 3 days was captured by Joseph Niépce, a French entrepeneur, who teamed up with Louis Daguerre in 1829.
View from the Window at Le Gras, 1826-27
This image is the one most often circulated and is a heightened copy of the original, with accentuated contrast.
Although Niépce had made salted images using a camera obscura as early as 1816, he was unable to preserve them. In 1817, he turned his attention to guaiacum, a resin produced by a small evergreen in tropical America, that would change colour and harden (become insoluble) upon exposure to sunlight. Niépce applied varnish to an etching, making the paper support translucent. Once the paper had dried, he placed it in direct contact with a pewter, copper, or tin plate coated with a thin layer of bitumen of Judea (which exhibited light sensitive attributes). The plate was then exposed to direct sunlight in contact with the varnished engraving and subsequently immersed in a bath of oil of lavender (today sold as an oil to instil feelings of love and peace), thinned with a white kerosene solvent, that dissolved the unhardened/unexposed bitumen of Judea.
Cardinal d'Amboise, 1827, Heliograph
By 1822 Niépce successfully produced a copy of this engraving by exposing a glass plate coated with bitumen of Judea that he had placed in contact with an engraving on paper. Bitumen of Judea is a photosensitive agent (light hardens it) that is natural asphalt, like tar.
In 1824, Niépce put a lithographic stone, coated with bitumen of Judea, inside his camera obscura, and after a rather lengthy exposure, made the very first "fixed"continuous tone image...a landscape. Unfortunately, this image was immediately lost when Niépce attempted to etch the stone for lithographic printing.
* Christopher James, The Book of Alternative Photographic Processes, Delmar Cengage Learning, 2007
** The National Media Museum/Science & Society Picture Library, London
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