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66 IV. MAKING 16-MM ORIGINALS
Color Reversal
The first successful color reversal 16-mm material to appear on the American market was Koda chrome — introduced commercially by the Eastman Kodak Company in 1935. Since its introduction, its use has grown by leaps and bounds.
Multi-layer color film with three separately sensitized emulsions coated in succession on to the same support was the subject of intensive study for many years ; it was first described by Schinzel in 1905. At that time there were no sensitizing dyes available which would remain in only one of the layers, nor was a means known for forming a satisfactory dye image in each layer separately. In 1913 Fischer patented the coupling development process, but he also found it difficult to keep the couplers in their separate layers.
Years later Mamies and Godowsky disclosed how to develop the separate layers to give differently colored dye images, and with the invention of improved "non-wandering" optical sensitizers, the Kodachrome process was developed. I. G. Farben (Agfa) in Germany invented colorforming couplers that could be placed in an emulsion and would not wander to an adjacent layer; such couplers are used in AnscoColor film.
Because the color separations that are effected in an integral tri-pack film such as Kodachrome or AnscoColor result in a considerable loss of light, individual emulsions of very high speed (and consequently coarse grain) are required to obtain a film of even relatively low speed. Thus, individual emulsions of exposure index of the order of 50 are needed to obtain an integral tri-pack of effective exposure index of 10 or 12. However, if exposure is controlled accurately, excellent results can be obtained with either Kodachrome or AnscoColor film due to the excellence of manufacture and of processing control exercised by their respective manufacturers despite significant color differences between them. Unfortunately the dyes in Kodachrome and AnscoColor are fugitive to some degree.
The fact that such integral tri-packs make excellent original materials for black-and-white release prints has been insufficiently recognized in the past. Critical professional film users have become aware of this and are turning to color reversal film as the original material for their black-and-white prints. Color reversal film as marketed has appreciably lower contrast than any finer grain reversal films now on the market and its users find it well worthwhile despite its higher cost and lower speed. The contrast and gradation of the Daylight (regular) and of the Mazda (Type A) color reversal films are similar; the contrast of Kodachrome