Submitted by Al …
(Adapted from The Encyclopedia of Photography ©1963)
In this five part series, we will look at the colour films produced by the Eastman Kodak Company.
The early history of colour goes back to James Clerk Maxwell who, in 1861, gave a lecture at the Royal Institution in London.
The talk was illustrated by a lantern slide of a coloured ribbon which had been made from three negatives taken respectively through a red, a green, and a blue solution. Some 50 years later this same principle was the basis of one of the first experiments conducted by the Kodak Research Laboratory. In a camera which used a triple lens, each coloured with the proper filter, three identical and adjoining pictures were taken simultaneously.
A triple lens projector was used, each lens also coloured with a filter. (For various reasons this system was not satisfactory and was never placed on the market.) The film used for this work was a panchromatic type made by Eastman Kodak Company in 1913, and the first such film sold by the company.
Even prior to 1912 when the Kodak Research Laboratory was started, the company had been carrying on experimental work in some screen-plate processes. The trademark Kodachrome was first applied to a two-colour process shown for the first time at the Pan-Pacific Exposition in 1915, but the process never reached commercial acceptance. In this process, worked out by J.G. Capstaff, the negatives taken through two filters were transformed directly into colour positive images. With the use of a mirror in the camera, one of the negatives was reversed laterally so that the two-colour positives could be superimposed face to face to make a completed transparency.
Experiments continued on this process in an attempt to apply it to motion-picture photography but were abandoned when the Technicolor Motion-Picture Corporation worked out its three-colour imbibition process.
A process, patented by R. Berthon in 1908, was licensed to Eastman Kodak Company in 1925, and the first film sold under the name Kodacolor was placed on the market. This was an entirely different film from the present Kodacolor Film and was used successfully for a number of years in making home movies in colour. In this process, tiny lenticular lenses were formed on the surface of the emulsion. A three-colour stop was used over the camera lens with the result that three-colour images made up of tiny dots were formed in back of the film. The advantage of this process was that the film could be processed as ordinary black-and-white film. A three-hole stop with red, green, and blue filters was placed over the projection lens.
The present multiple coating system of photography had its practical birth with Leopold Mannes and Leo Godowsky Jr, who joined the staff of the Kodak Research Laboratories in 1930. Their experiments were devoted to making colour pictures by means of multiple emulsion coatings, one on top of the other. Each layer was treated with a sensitizing dye to form an accurate three-colour image by means of an integral tripack.
While the Research Laboratory worked on practical methods of making these integral tripacks, Mannes and Godowsky worked on methods for processing them. They adopted coupler development, but instead of putting the couplers into the emulsion, the introduced them during processing. As a result of these experiments, Kodachrome Film, as we know it today, was introduced in 1935.
HOW KODACHROME IS MADE
Kodachrome Film has four coatings. The one nearest the base is strongly red-sensitive. On top of this is a green-sensitive emulsion overcoated with a yellow-absorbing layer to act as a filter. Above both of these is a top coating which is blue-sensitive. When a picture is taken upon the film, the three colour components are automatically separated in the depth of the coating. The red component is in the red-sensitive emulsion, the green component in the middle layer, and the blue component in the top layer. In processing, each component of an image is transformed into a positive image consisting of a suitable dye. The complex development process is completed when the silver is removed from all three image layers and the filter layer removed at the same time, leaving only the dye images.
The first Kodachrome Film was introduced in 1935 as 16mm motion-picture film and rapidly displaced the lenticulated Kodacolor process. Later, it was introduced for 8mm motion pictures. In 1936, Kodachrome Film was produced commercially in 35mm size. At first its acceptance was quite limited, but sales were greatly accelerated when the Eastman Kodak Company began to mount all customers’ Kodachrome transparencies in cardboard frames as a part of the processing service. In 1941 Kodachrome prints were introduced. These were made in the processing laboratory using a Kodachrome emulsion coated on a white pigmented film base.
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