Heliography
Encyclopedia
Heliography is the photographic
Photography
Photography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...

 process invented by Joseph Nicéphore Niépce
Nicéphore Niépce
Nicéphore Niépce March 7, 1765 – July 5, 1833) was a French inventor, most noted as one of the inventors of photography and a pioneer in the field.He is most noted for producing the world's first known photograph in 1825...

 around 1822, which he used to make the earliest known permanent photograph from nature, View from the Window at Le Gras
View from the Window at Le Gras
View from the Window at Le Gras was the first successful permanent photograph, created by Nicéphore Niépce in 1826 at Saint-Loup-de-Varennes....

(c. 1826). The process used bitumen (an asphalt like substance), as a coating on glass or metal, which hardened in relation to exposure to light. When the plate was washed with oil of lavender, only the hardened image area remained.

The word has also been used to refer to other phenomena: for description of the sun (cf geography), for photography in general, for signalling by heliograph
Heliograph
A heliograph is a wireless solar telegraph that signals by flashes of sunlight reflected by a mirror. The flashes are produced by momentarily pivoting the mirror, or by interrupting the beam with a shutter...

 (a device less commonly called a heliotrope
Heliotrope (instrument)
The heliotrope is an instrument that uses a mirror to reflect sunlight over great distances to mark the positions of participants in a land survey. The heliotrope was invented by the German mathematician Carl Friedrich Gauss....

 or helio-telegraph), and for photography of the sun.

The abbreviations héliog. or héliogr., found on old reproductions, may stand for the French word héliogravure, and can then refer to any form of photogravure
Photogravure
Photogravure is an intaglio printmaking or photo-mechanical process whereby a copper plate is coated with a light-sensitive gelatin tissue which had been exposed to a film positive, and then etched, resulting in a high quality intaglio print that can reproduce the detail and continuous tones of a...

.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK