Sunwriting: Brief history of heliography & the making of the world's oldest surviving photograph
View from the Window at Le Gras (c. 1826 — 1827) is the world’s first camera photograph, or — at the very least — its oldest surviving one. It was taken by Joseph Nicéphore Niépce (1765 — 1833) from a second-story window of his family estate in the village of Saint-Loup-de-Varennes using a novel photographic process called heliography; because it produced one-a-kind-images, there is one only copy of the historic piece and it is a part of the permanent collection at the University of Texas-Austin.
Niépce was an accomplished French inventor who, around the 1920s, became “fascinated with the printing method of lithography, in which images drawn on stone could be reproduced using oil-based ink.” Notoriously lacking artistic talent, Niépce was motivated by two goals — recording real life scenes using a camera, and being able to duplicate the images afterwards. The increasingly growing popular demand for affordable pictures only served as additional drive.
Comprised of the Greek words helios (sun) and graphein (writing), heliography — or héliographie in French — translates to sunwriting. Niépce coined the term after he realized that Bitumen of Judea, a naturally occurring asphalt that hardens when exposed to light, was the key to his ultimate success.
According to Processes in Photoreactive Polymers (1995), edited by V.V. Krongauz and Alexander D. Trifunac:
“He dissolved the powder of bitumen in lavender oil to make a concentrated solution...Next, he spread this solution on a support...and dried it by heating. This led to the production of a bright golden brown varnish. Under the action of light, this varnish became insoluble in the lavender oil. After exposure, Niépce immersed the varnish with its support in a bath of lavender oil diluted with white petroleum. Parts of the images that had not received light were still soluble in lavender oil, while those illuminated were not dissolved and stayed on the support. The variation of solubility made it possible to reproduce the difference between light and shadow.”
The process, however, produced a negative of an image, and Niépce really wanted a positive. For the View from the Window at Le Gras, the inventor used a polished, 6.4 in × 8 inch pewter plate treated with the light-sensitive material dissolved in lavender oil; Niépce inserted the plate into his camera obscura, a device that captured and projected scenes illuminated by sunlight, and “trained it on the view outside his studio window.” After several days of exposure to sunlight, the bitumen hardened in the brightly lit areas and yielded an impression of his courtyard.
Note* Both images are in the public domain, via Wiki