In this method as in other methods of color photography, independent color value negatives are first obtained. The Harriscolor process can employ one of the following two methods: Either a camera wherein the dividing light prisms are incorporated inside the camera, or two Bell & Howell cameras with a light-splitting device placed in front of the camera lenses can be used.
The first method uses a small surface silvered mirror placed behind the lens. Portions of the silver are removed from the mirror in the form of fine lines or circles and the mirror is placed at an angle of 45 to the lens. One film is placed directly back of the mirror with the emulsion side facing the lens and a second film placed at right angles to this first film. The two films can be either both panchromatic or one panchromatic and the other orthochromatic. If they are both panchromatic, then obviously two complementary color filters are used in obtaining the color value negatives. If orthochromatic and panchromatic negative is used, then only one color filter is necessary and that color filter would be red. The light passing through the lens then passes to the mirror. The silvered portions of the mirror will reflect the image at right angles and that image will then be recorded on one negative. The clear portions of the mirror, that is, where the silver has been removed, will allow the image to pass through and this will be recorded on the second negative.
If an orthochromatic and panchromatic combination is used, greater exposure will result since the absorption by one filter is removed. Since the orthochromatic film is insensitive to the red end of the spectrum, no color filter would be necessary since that negative would automatically record the blue-green end of the spectrum and the amount of exposure, which would ordinarily be absorbed by a color filter, can be compensated for in the construction of the reflecting mirror to the advantage of the negative which is back of the reflecting medium.
While for the point of illustration reference is made to the light-splitting device as a mirror, it should be understood that the two right angle prisms, one having the surface treated as already described, are cemented together.
With the method which employs two Bell & Howell cameras, these cameras are mounted on a base at right angles to each other. Arranged between the two lenses is a device, which for the sake of illustration we will call a transparent mirror, that is, a mirror capable of reflecting light and transmitting light. Procedure of photographing and the combination of negatives and color filters used are precisely the same as already described and with this method the light first comes in contact with the transparent mirror and is reflected at an angle of 90 degrees to one camera and at the same time the light which passes through the mirror is recorded on the negative directly back of the mirror.
So far then, we have described the methods of obtaining color value negatives. Harriscolor does not employ double-coated film in the manufacture of their color prints but uses single-coated film or film with one or more emulsions on one side of the celluloid base. The negative carrying the red color value images is printed through the base of the positive film and this film is then developed, washed, and colored with an iron solution and again washed and dried in the dark.
Onto the residual emulsion, which, of course, is on the surface of the emulsion, are printed images from the blue color value negatives. This in turn is developed in a solution that does not necessarily destroy the ferric image; the whole film is fixed and washed and the top image toned with the color complementary to the bottom image and with a bath which does not affect the existing blue image. The base of the film has a slight yellow tint which, it is claimed, gives an illusion of three-color photography.”
(Report of the Color Committee. In: Journal of the Society of Motion Picture Engineers, 15, Nov. 1930, pp. 721-724, on pp. 722-723.)
Original Technical Papers and Primary Sources
Society of Motion Picture Engineers (1930): Report of the Color Committee. In: Journal of the Society of Motion Picture Engineers, 15, Nov. 1930, pp. 721-724, on pp. 722-723. View Quote
Eggert, John (1932): Kurzer Überblick über den Stand der Farbenkinematographie. In: Bericht über den VIII. Internationalen Kongress für wissenschaftliche und angewandte Photographie, Dresden 1931. Leipzig: J. A. Barth, pp. 214–221, on pp. 215–218. (in German) View Quote
Nowotny, Robert A. (1983): The Way of All Flesh Tones. A History of Color Motion Picture Processes, 1895-1929. New York: Garland Pub., pp. 192-193. View Quote
Ryan, Roderick T. (1977): A History of Motion Picture Color Technology. London: Focal Press, pp. 86-87. View Quote
U.S.P. 1,825,863 (Harris, Joseph B. Jr.; filed March 22, 1929; granted Oct. 6, 1931)Download PDF