grainless+plate

SUBJECT AREA: Photography, film and optics

[br]

[br]

[br]

Born of French parents, Lippman's work began with a distinguished career in classics, philosophy, mathematics and physics at the Ecole Normale in Luxembourg. After further studies in physics at Heidelberg University, he returned to France and the Sorbonne, where he was in 1886 appointed Director of Physics. He was a leading pioneer in France of research into electricity, optics, heat and other branches of physics.

In 1886 he conceived the idea of recording the existence of standing waves in light when it is reflected back on itself, by photographing the colours so produced. This required the production of a photographic emulsion that was effectively grainless: the individual silver halide crystals had to be smaller than the shortest wavelength of light to be recorded. Lippman succeeded in this and in 1891 demonstrated his process. A glass plate was coated with a grainless emulsion and held in a special plate-holder, glass towards the lens. The back of the holder was filled with mercury, which provided a perfect reflector when in contact with the emulsion. The standing waves produced during the exposure formed laminae in the emulsion, with the number of laminae being determined by the wavelength of the incoming light at each point on the image. When the processed plate was viewed under the correct lighting conditions, a theoretically exact reproduction of the colours of the original subject could be seen. However, the Lippman process remained a beautiful scientific demonstration only, since the ultra-fine-grain emulsion was very slow, requiring exposure times of over 10,000 times that of conventional negative material. Any method of increasing the speed of the emulsion also increased the grain size and destroyed the conditions required for the process to work.

[br]

SUBJECT AREA: Photography, film and optics

[br]

[br]

[br]

Auguste and his brother Louis Lumière (b. 5 October 1864 Besançon, France; d. 6 June 1948 Bandol, France) developed the photographic plate-making business founded by their father, Charles Antoine Lumière, at Lyons, extending production to roll-film manufacture in 1887. In the summer of 1894 their father brought to the factory a piece of Edison kinetoscope film, and said that they should produce films for the French owners of the new moving-picture machine. To do this, of course, a camera was needed; Louis was chiefly responsible for the design, which used an intermittent claw for driving the film, inspired by a sewing-machine mechanism. The machine was patented on 13 February 1895, and it was shown on 22 March 1895 at the Société d'Encouragement pour l'In-dustrie Nationale in Paris, with a projected film showing workers leaving the Lyons factory. Further demonstrations followed at the Sorbonne, and in Lyons during the Congrès des Sociétés de Photographie in June 1895. The Lumières filmed the delegates returning from an excursion, and showed the film to the Congrès the next day. To bring the Cinématographe, as it was called, to the public, the basement of the Grand Café in the Boulevard des Capuchines in Paris was rented, and on Saturday 28 December 1895 the first regular presentations of projected pictures to a paying public took place. The half-hour shows were an immediate success, and in a few months Lumière Cinématographes were seen throughout the world.

The other principal area of achievement by the Lumière brothers was colour photography. They took up Lippman's method of interference colour photography, developing special grainless emulsions, and early in 1893 demonstrated their results by lighting them with an arc lamp and projecting them on to a screen. In 1895 they patented a method of subtractive colour photography involving printing the colour separations on bichromated gelatine glue sheets, which were then dyed and assembled in register, on paper for prints or bound between glass for transparencies. Their most successful colour process was based upon the colour-mosaic principle. In 1904 they described a process in which microscopic grains of potato starch, dyed red, green and blue, were scattered on a freshly varnished glass plate. When dried the mosaic was coated with varnish and then with a panchromatic emulsion. The plate was exposed with the mosaic towards the lens, and after reversal processing a colour transparency was produced. The process was launched commercially in 1907 under the name Autochrome; it was the first fully practical single-plate colour process to reach the public, remaining on the market until the 1930s, when it was followed by a film version using the same principle.

Auguste and Louis received the Progress Medal of the Royal Photographic Society in 1909 for their work in colour photography. Auguste was also much involved in biological science and, having founded the Clinique Auguste Lumière, spent many of his later years working in the physiological laboratory.

[br]