FED-Color prototype by K. Dobrovolsky
By Vladislav Kern
“FED-Color” (made up designation for the purpose of this article) is a 35mm tri-filter prism-based color camera based on a FED body by constructor K. Dobrovolsky. The goal was to create a portable camera that is capable of color photography.
The idea was to capture light via lens and use a prism to evenly distribute the picture onto three frames, where each frame is located behind a color component filter (yellow, blue and green). A combination of the three black and white images via a special projector would result in a color image. The solution in this camera consists of a complex prism system made up from four prisms and glued together into a cube that is very similar to the one used by “Technicolor” system.
Edges a,b,c and d and prism I,II and III (see camera/prism schematic) are covered in the thinnest layer of platinum that reflects ⅔ of the light. The prism system was extremely difficult to assemble and required almost molecular-like precision on the part of opticians.
The camera body is completely metal, in a FED-fashion, there is a automatic rangefinder, viewfinder, advance mechanism knob and a shutter release button on top cover.
The prism itself is located immediately behind the shutter curtain and is mounted to the top cover with two aluminum pegs and connected by steel rods that at the same time serve the purpose of being roller axles for film transport.
The frame windows are located opposite of the three sides of the prism in such a way that the three frames are all next to each other on a regular negative film roll. The distance between frames is a bit larger than usual - 4.5mm.
To minimize the light loss, special filters were developed for this camera, with specs very close to high end American filters at the time but having more transparency factor.
The filters are located between the frame windows and the prism. The loading of the camera and the image capture on this camera does not differ from a regular process on a FED, the shutter cocks at the same time with the film advance which moves the film 3 frames. It uses standard film cassettes, and on a standard length of film of 1.6 meters it fits 36 frames which translates to 12 color images. During the exposure there is a special mark that is stamped to each frame that marks which color filter it was shot with.
A lens is mounted with a regular 39mm thread but with a difference that the rear element is located almost flush to a shutter curtain.
The camera does require 20 times longer shutter speed in comparison to regular FED in order to capture the same exposure. The idea was that the usage of fast lens and high sensitivity film will help in reducing that exposure time.
Focusing Distance: 50,75,100
Maximum shutter speed: 1/500
Exposure time: 37 seconds
Source: Soviet Photo Magazine 1941 #4
Special thanks to Vladimir Zverev for providing the material!