1950 – 1966
Additive 3 color: Beam-splitter
Ryan, Roderick T. (1977): A History of Motion Picture Color Technology. London: Focal Press, pp. 47-48.
“In May 1950, Colorvision, Inc., was formed for the purpose of developing a three-color additive system of color cinematography for the newly emerging field of color television. According to the promotional literature of the company the additive system of color photography was chosen for the following reasons:
1. Maximum economy in photographing.
2. Maximum color rendition.
3. Maximum scope for color control.
4. Maximum facilities for processing of film.
5. High speed in processing of film.
Actual work on the proposed system began in March 1951. Studies of the additive method were made and an optical system was devised which would meet the following requirements:
1. Sufficient light transmission for use at low levels of illumination.
2. Freedom from both time and spatial parallax.
3. Availability of a wide choice lens to permit a choice of angle of view.
4. Compatibility with existing equipment.
To confirm the practicability of the proposed system an experimental model of the camera optical unit was made and a 1000 foot test reel was prepared. This film was shown privately in four theaters in California in April 1952. Comments regarding the film were very favorable at all four showings. Therefore, work was started on the construction of regular production models of the Colorvision optical unit.32
In October 1954 the Colorvision process was described and demonstrated at the Society of Motion Picture and Television Engineers Convention at Los Angeles.33 Since then the company’s efforts have been directed toward the design and construction of a complete operational system which would meet the requirements of the professional producer.
A status report and a further demonstration of the process was given at the Society of Motion Picture and Television Engineers Convention at Los Angeles in April 1958.34 Improvements in the basic system were shown and the practicability of using the Colorvision system for color kinescope recording was confirmed. At this time it was announced that four Colorvision optical units for use with N. C. Mitchell cameras were operational and that an optical unit has been aligned with an Acme Process Camera for animation, titling, etc.
The third paper concerning the Colorvision process was presented at the Society of Motion Picture and Television Engineers Convention at Los Angeles in March I965.35 This paper described an application of the process to current laboratory practice. In the making of separation positives for protection or archival storage it was proposed that the Colorvision system of area sharing be used in place of three separate films.
The Colorvision optical system was a beam-splitter with a relative aperture in excess of f / 2.0. The light which entered the system through a single entrance pupil was divided into its red, green and blue components by means of multilayered interference filters and forms three geometrically similar images at the film plane. Each image had an area 40 per cent greater than that of a normal 16 mm frame. Exposures were made on fast black and white panchromatic negative in an unmodified N. C. Mitchell camera. Normal Mitchell accessories such as matte box, view finder, etc., were also used. Each unit was provided with interchangeable bayonet-mounted 35 mm, 50 mm, 75 mm and 125 mm objective lenses. The basic exposure level was 200 ft candles for Eastman Tri X Panchromatic Negative Film, Type 5233 and 400 ft candles for Eastman Plus X Panchromatic Negative Film, Type 4231 at Colorvision aperture T-2. Depth of field at this aperture was equal to a normal lens aperture of f / 4.5. After exposure the negative was processed in a conventional black and white developer to a gamma of 0.60, fixed, washed and dried. Daily prints could be made by continuous contact printing on black and white print film for additive projection in color or they could be made by optical superimposition on subtractive color film. For final release printing, a 35 mm superimposed master positive could be made on Eastman Color Intermediate Film, Type 5253, or a set of three matrices could be made for Technicolor release.
If the process was used for the making of protection master positives as proposed by L. H. Wheeler in 1965, all three master positives were produced on a single roll with a single pass through the printer. This resulted in considerable savings in labor, film cost, and processing cost, as well as a reduction by two-thirds in the amount of storage space necessary for storing the protection master positives.
Although this system produced excellent results and fulfilled a real need, the Colorvision Corporation went bankrupt! The company’s remaining assets were sold at auction in April 1966. The printing equipment that Colorvision had proposed to use for making protection master positives was purchased by Consolidated Film Industries.
32 “Colorvision—A New Additive Process for Color Photography” (Los Angeles: Colorvision, Inc., 1954), p. 2.
33 BRUNSWICK, L. F., “Separation Process for Additive Color Motion Picture Photography on Black and White Film,” Journal of the Society of Motion Picture and Television Engineers, March, 1955, pp. 126-128.
34 WHEELER, L, H., “A New Additive Color System for Motion Picture Photography,” Journal of the Society of Motion Picture and Television Engineers, November, 1958, pp. 747-749.
35 WHEELER, L. H., “A New Color Separation Technique for Color Negative Protection,” Paper presented at the 97th Conference of The Society of Motion Picture and Television Engineers, Los Angeles, March 30, 1965.”
(Ryan, Roderick T. (1977): A History of Motion Picture Color Technology. London: Focal Press, pp. 47-48.)