Agfa bipack films
AGFA BIPACK FILM
The front film is orthochromatic and sensitive, therefore, to green and blue. The rear film is panchromatic and records red-orange only, there being a red-orange filter on the orthochromatic emulsion. In fact, this is a bipack of the standard type. The two films, according to the Agfa booklet, Kine-Negativ-Material, are perforated simultaneously, and the two emulsions are carefully balanced for contrast and speed, the utmost being done to ensure maximum spectral selectivity. Owing to the high transparency of the front film, and the high speed of the combined pack, the exposure needed is not greatly in excess of black-and-white. The red-orange filter on the front film almost entirely eliminates halation due to the reflection of light from the rear film as the blue rays and green rays are entirely absorbed (to which the front film is sensitive). The orange filter should disappear almost immediately on immersion in the developer. (Fig. 133.)
The spectral sensitivity is so balanced that it is unnecessary to use any compensating filter when using tungsten lamps for illumination; while for daylight or arc light the Agfa No. 2 yellow filter can be used to reduce the preponderance of blue Magenta and violet. Agfa recommend that only cameras equipped with pilot pins should be used in order to ensure perfect registering when making the colour prints afterwards. This is essential in any colour process.
The film has been manufactured mainly for two-colour processes. For this purpose Agfa make a double-coated positive film known as Agfa-Dipo-Film. This material can be double-toned by any of the well-known toning and dye mordanting processes. Such a material is used, for example, by the Spectracolour process.
(Klein, Adrian Bernhard = Cornwell-Clyne (1940): Colour Cinematography. Boston: American Photographic Pub. Co.. 2nd revised edition, pp. 318-320.)
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Agfa bipack film samples from the Kodak Film Samples Collection at the National Science and Media Museum in Bradford.
Credit: National Science and Media Museum Bradford.
Photographs by Josephine Diecke, SNSF project Film Colors. Technologies, Cultures, Institutions and Joëlle Kost, ERC Advanced Grant FilmColors.
Dr. N. (1937): Mehrschichten-Film. In: Film-Kurier, 27.8.1937, Serie „Farb-Film-Fibel”. (in German)
Eggert, John; Heymer, Gerd (1937): Der Stand der Farbenphotographie. In: Veröffentlichungen des wissenschaftlichen Zentral-Laboratoriums der photographischen Abteilung Agfa, pp. 7–28, on pp. 10–12and on pp. 17–18. (in German)
Finger, Erhard (1994): Die Filmfabrik Wolfen. Porträt eines traditionsreichen Unternehmens 1909 bis 1994. GÖS-Gesellschaft für Sanierungsmaßnahmen Wolfen und Thalheim mbH, Filmfabrik Wolfen GmbH i.L., pp. 27-28.
Klein, Adrian Bernhard = Cornwell-Clyne (1940): Colour Cinematography. Boston: American Photographic Pub. Co.. 2nd revised edition, pp. 318-320.
Anonymous (1937): Farbig. Genschows Rotkäppchen-Film. In: Film-Kurier, No. 283, 6.12.1937. (in German)