Three-color camera

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Three-color cameras (color separation cameras) make separate monochrome negatives of the three primary-color components of the photographed image, to be used in color printing. This process precedes the invention of color plates or film. Even when colour plates such as Autochrome became available, printing from them was considerably more difficult than from color-separation negatives. Color-separation studio cameras continued to be made for demanding uses until the 1950s, twenty years after the introduction of Kodachrome.

In early color-separation cameras, three plates are exposed sequentially, with a red, blue and green filter respectively. Clearly, this method is not appropriate for subjects that move significantly between the exposures. However, in principle, any camera can be used for this method. Cameras sold as three-color cameras are hardly different from any other camera, except that they are provided with the correct filters. Some (for example Dr Miethe's Dreifarben-Kamera by Bermpohl, who specialised in cameras for this process) have a repeating back to allow the three exposures to be made in quick succession, and special dark-slides that hold a set of three plates side by side; in the falling-plate magazine camera shown below, the plate magazine serves the same purpose.

In the late 1920s, cameras began to be made that make the three negatives simultaneously, extending the method to more subjects. These one-shot three-color cameras use internal arrangements of half-silvered mirrors to divide the light from the lens into three parts, and direct each part to a plate (or in later cameras, film or even digital image sensor, in such cameras as the Minolta RD-175). The three images are later combined to form a full-colour image. The first 3-color camera of this one-shot type was presented in 1897 by color photography pioneer Louis Ducos du Hauron.