Heliograph

"Heliography" was first conceived by inventor, Joseph Nicéphore Niépce, to deliniate the he obtained the first permanent photographic images. The name is derived from Greek - helios "sun" and graphein "writing," or drawing.

Niépce was the first invidual to produce a permanent latent image using a photochemical process. The heliographic process spawned from experimentation in lithography. Niépce, was an ianaquate draftsman, he endeavored to explore another manner to visually record a scene. He started with light-sensitive varnishes and eventually silver chloride latented images captured in camera. His shortfall was fixing the captured image for any degree of permanance. Niépce eventually began coating his supports with a solution of bitumen of Judea, an asphalt compound used as a resist in engraving and often coupled with lithography. He observed that bitumen bleached to a light gray color through exposure to light and hardened through the catalyst of the solvents turpentine and lavender oil.

Using a glass plate support coated with bitumen, in 1822 Niépce exposed a contact imaged under an engraving of Pope Pius VII. The print had was oiled so the paper was near transparent. The sunlight hardened the coating to the glass, but areas darkened by the image remained soluble. Using lavender oil the unfixed portions dissolved, resulting in a transparent, thin-lined image. When illuminated the image was comprised of bright lines with darker opaque fields from the opaque coating. When placed in front of a dark surface and illuminated, the result appeared black with light gray areas. This original image was accidentally destroyed during an attempt to reproduce it years later.

Niépce experimented with bitumen on pewter or zinc plates for several years which he would ink and print. In 1826 with an engraving of the Cardinal Georges d'Amboise he finally mastered his process. Using the bitumen of Judea and lavender oil process and utilizing a pewter plate as a support. He contact printed the engraving, dissolved out the soluble bitumen, and put the plate in an acid bath. The hardened areas of the bitumen acted as a resist, only the revealed metal in the lines left in the etching. These intaglio heliographic plates were utilized for final proofs. In doing so, Niépce produced the first photomechanical reproduction.

Finally (and most likely also in 1826) the chemical process, the power of the camera, the successful quest for permanence, and the combined curiosity and clarity of the inventor, all came remarkably together; Joseph Nicéphore Niépce made the first permanent photography from nature. After coating a pewter plate with the same solution of bitumen of Judea, he placed the plate into a camera focused upon the sunlit scene looking out from the third-floor window of his house at Le Gras. The exposure is recorded as having been around eight hours in duration. The brightest parts of the scene bleached and hardened the bitumen. When developed in the oil of lavender and turpentine, some coating in the partly exposed middle tones and all the coating in the unexposed shadow areas, was dissolved away, revealing the dark gray metal beneath. The resulting image is therefore a direct positive: the light sections being the hardened bitumen, the darks ones being the actual pewter plate surface.

Joined in partnership with Louis Jacques Mandé Daguerre in 1829, Niépce did little more with the heliograph. Upon his death in 1833, his son Isidore would take his place in the partnership but no further improvements in the process were forthcoming. By the time of their public announcement in 1839, Daguerre and his daguerreotype process far outshone his associate's pioneering contribution to photography. A few remaining examples of Niépce's heliographs still exist today, but they cannot surpass the uniqueness and beauty of this first permanent photograph from nature.