Nicéphore Niépce and Daguerre
The first photographic process or heliography was invented by Nicéphore Niépce around 1824. The images were obtained with Judean bitumen spread on a silver plate , after an exposure time of several days. In 1829, Niépce associated with his research, Louis Jacques Mandé Daguerre. In 1832, they developed, from the residue of the distillation of the essence of lavender, a second process producing images in one day of exposure time.
Hippolyte Bayard, 1801-1887
Niépce died in 1833, Daguerre continued the work alone and invented, in 1838, the daguerreotype , the first process comprising a development stage. A silver plate covered with a thin layer of silver iodide was exposed in the dark chamber and then subjected to mercury vapors which caused the appearance of the invisible latent image formed during exposure to the light. This development consisted of such an amplification of the effect of light, that the exposure time did not exceed 30 minutes. Fixing was obtained by immersion in water saturated with sea salt.
Hippolyte Bayard
In July 1839, another Frenchman Hippolyte Bayard discovered the means of obtaining directly positive images on paper . A paper covered with silver chloride was blackened in the light and then exposed in the dark room after impregnation in silver iodide. The exposure time was 30 minutes to 2 hours.
Fox Talbot, 1800-1877
William Henry Fox Talbot
Also in 1839, the announcement of the invention of the daguerreotype prompted the Englishman William Henry Fox Talbot to resume interrupted research, the beginnings of which dated back to 1834. In 1841, he patented the calotype, the first negative/positive process which allowed the multiplication of the same image by obtaining an intermediate negative on silver chloride paper made translucent with wax. As for the daguerreotype, the latent image was then revealed by means of a chemical product, the developer: a solution of gallic acid and silver nitrate. A second sheet of paper also coated with silver chloride was then exposed through the translucent negative, to give the final positive.
John Herschell
John Herschell, 1792-1871
We owe John Herschell to have discovered, in 1839, the means of fixing these images by immersing them in a bath of sodium hyposulphite which is still today the essential compound of photographic fixers. The advantages of the calotype lay mainly in the ease of handling the paper proofs and the possibility of multiple reproduction. On the other hand, the definition, limited by the presence of the fibers of the negative paper, could not compete with the daguerreotype.
Hippolyte Fizeau
To further reduce the exposure time, short focal length lenses were created, which were therefore brighter, while maintaining sharpness over the entire image. In 1841, the physicist Fizeau replaced silver iodide with silver bromide, whose sensitivity to light is much higher. It only took a few seconds of exposure to obtain a daguerreotype and it became possible to make portraits.
Abel Niépce de Saint-Victor
In order to improve the transparency of the calotype negative, Abel Niépce de Saint-Victor, Niépce’s second cousin, discovered in 1847 the means of replacing the paper with glass . So that the silver bromide can adhere to the glass, he had the idea of ​​mixing it with albumin (egg white). Although a little too contrasting, the images then became extremely precise, forcing opticians to develop even better lenses.
Scott ArcherIn 1851, the Englishman Scott Archer replaced albumin with collodion, the basis of which is cotton powder. The black and white images obtained by this process reached a quality never before obtained. The only drawbacks, the shooting had to take place as long as the plate was wet and the development to be carried out immediately afterwards.
Richard Maddox, 1816-1902
Richard Maddox et Charles Bennet
In 1871, another Briton, Richard Maddox, remedied this problem by replacing collodion with gelatin , a procedure perfected by Charles Bennet who showed that gelatin plates acquired great sensitivity when kept for several days at 32°C. . Not only could the gelatin-bromide plates then be stored before use, but their sensitivity was such that the exposure could not exceed a fraction of a second.
It was then, a little before 1880, that the history of the shutter began , since the high sensitivity of the plates required the design of mechanisms capable of letting light into the device for 1/100 and even 1/1000 of a second. It was necessary to precisely evaluate the intensity of the light and the exposure meter then became a real measuring instrument.
George Eastman, 1854-1932
Georges Eastman
The American Georges Eastman, founder of Kodak, will conceive, in 1888, the idea of ​​the flexible support. The glass plates will be gradually replaced by rolls of celluloid.
Color reproduction
What still lacked in photography was color reproduction. The first attempts were at the initiative of Edmond Becquerel in 1848, then of Abel Niépce de Saint-Victor in 1851 who showed that a silver plate covered with pure silver chloride directly reproduced the colors, but in an unstable way. .
In 1869, Louis Ducos du Hauron succeeded in Agen, the first color photography by applying the principle demonstrated by Maxwell of the decomposition of light by the three fundamental colors, red, yellow and blue. He took three photos of the same subject, through a red, blue and yellow filter respectively. He obtained 3 positives which he colored in the color which had produced them. By superimposing the three images exactly, he obtained the restitution of the colors.
Self-portrait of Gabriel Lippmann
The physicist Gabriel Lippman received the Nobel Prize in 1906, for having discovered in 1891, the means of obtaining direct color photos on a single plate, by an interferential process which already prefigured holography. Too complex, this invention only remained at the laboratory stage.
The first monoplate color process that could be used by amateurs was born in 1906. The autochrome invented by the Lumière brothers took up the principle of trichrome synthesis, this time carried out on a single plate by adding a mosaic of microfilters of the three colors produced by means of potato starch grains.
The discovery of the “color developer” by R. Fisher in 1911 gave color photography a new direction. It had been noticed that certain developers led to the obtaining of images tinted with a color, instead of being in black and white.
The brothers Auguste Lumière (1862-1954) and Louis Lumière (1864-1948).
The trichrome principle was taken up by the Agfa Company to develop in 1936, Agfacolor films consisting of three superimposed layers sensitive respectively to blue, green and red. A developer was developed which colored each of the layers in the color of its sensitivity. The overlay led to a color image. Here again the possibility of reproducing the colors caused improvements in optics, to faithfully transmit the colors of the photographed object to the film.
In 1935 two Americans L. Mannès and L. Godowsky improved the process. Purchased by Kodak, it took the name of Kodachrome. Although our current color films are very sophisticated, the fact remains that they still use silver bromide, gelatin and the basic principle of Agfacolor and Kodachrome.
