1824-1829 — Invention of Photography
In 1824, Nicéphore Niépce puts lithographic stones, coated with bitumen, at the back of a camera obscura and obtained for the first time ever a fixed image of a landscape. This required an extremely long exposure time, in broad daylight, for a few days.
On September 16, 1824, Nicéphore Niépce wrote to his brother Claude, then living in England, the following words: “I am pleased to finally be able to announce to you that, thanks to the refinement of my processes, I have succeeded in obtaining a view as I had wished for, though I scarcely dared to hope for it, as until now, my results had been very incomplete. This view was taken from your room facing Le Gras; and for this purpose, I used my largest camera obscura and my largest plate. The image of the objects is rendered with astonishing clarity and fidelity, down to the finest details and their most delicate shades. Since this counter-proof is almost uncolored, one can best appreciate its effect by looking at the plate obliquely: it is then that it becomes perceptible to the eye, through the shadows and light reflections; and this effect, I must say, my dear friend, truly has something magical about it. (…) In the meantime, you can, as of today, consider the success of applying my processes to views, whether on stone or on glass, as a demonstrated and indisputable fact.”
This letter marks the birth of photography, whose bicentenary is celebrated in 2024.
Starting in 1825, he regularly used copper as a base, then tin in 1826, while also realising etched images.
In 1827, Niépce went to England, where he found his brother dying, without any improvements to the engine at hand. He realised then that they would never get any profit from this invention into which they had invested so much hope. After having vainly tried to get the attention of the Royal Society as to his reproduction process of images, called heliography, Niépce returned to France and relentlessly worked on improving his invention. In 1828, he found a new method that led to superior quality images with half-tones. Using polished silver as a base and letting iodine vapours interact with the bitumen image, he obtained genuine photographs in black and white on a metal plate. The preciseness of these images was amazing for the time. The exposure time was still many days in broad sunlight.
Principle and Technique of Heliography with the Camera Obscura
The photosensitive agent is bitumen of Judea, which is a sort of natural tar known from ancient times. People in antiquity used to collect it from the Dead Sea surface (in the Greek Asphaltite lake), where it kept surfacing continually from the bottom of the sea. It was used by the Egyptians to embalm mummies, to caulk ships or even to make terrace works in Babylon. In the 19th century, people already knew how to extract this tar from bituminous rocks, and as a matter of fact the bitumen used by Niépce did not come from Judea anymore.
1 – How to obtain a negative by means of bitumen of Judea
› Niépce dissolved powdered bitumen of Judea in lavender oil.
› Then he spread this solution in a very thin layer on a base ( glass, stone, copper, tin, silver).
› With a hot drying process he got a shiny varnish with a cherry red color.
› He would then expose the varnished plate in a camera obscura (here a slide projection).
› After exposure, there was no visible image. Niépce would dip the plate in a diluted lavender oil bath that would dissolve the bitumen parts that had not been exposed or very little to light.
› The resulting image, seen with a normal incidence, was negative.
The exposure time in a camera obscura was quite a few days in broad sunlight.
2 – Utilization of a Judea bitumen image
› To get a positive image , Niépce used the image in two ways : without any further processing under the condition to make this image with an extremely thin layer of varnish with a slight underexposure (from 1827 on). In this case the varnish was mat and by reflection , with a low angled light and in a dark place , the image would appear as a positive.
› Submitting the silver plate to iodine vapors to get a positive image (from 1828 to 1831) Niépce would place it in a box with iodine crystals that evaporated spontaneously.
› Within a few minutes the iodine fumes oxydized the silver insufficiently protected by the varnish. This created a layer of silver iodide on the metal surface, which once the varnish was eliminated, would blacken under the action of light.
› He would get a positive image.
> Discover Spéos, the photography school that preserves the Niépce House
