For this four-color process, the light beam was decomposed into four parts, each of which simultaneously exposed an area equal to one quarter of the 35mm frame of a black and white negative. This was obtained optically by placing a diaphragm and a secondary objective on the focal plane of the main lens; once a clear and all-over defined image was achieved, a dividing prism obtained the quadruple decomposition and deviated the four rays to the same number of filters, behind which the sensitive emulsion was placed.
In the following versions, various modifications were implemented in order to reduce problems and improve the system’s performance.
In the last version, the light beams that form the four images on the frame go through a nearly identical and symmetrical path, in such a way as to make the four monochromatic separation records perfectly superimposable in projection. In case this were to fail, a special correction device would have given the projectionist the possibility to obtain the desired result. Also very important was the introduction of a diaphragm system to regulate the intensity of the light beam that reached each of the four filters. In fact, as it was impossible to make corrections to the individual selections while developing the film (since they were placed next to each other on the same film and, therefore, had to be developed together) it was necessary to balance the amount of light for the four filters during shooting.
This path was reversed during projection: using a projector equipped with the same optical system to the one used for filming, the four black and white color separations each went through their corresponding filter, the prism and the corresponding portions of the secondary frame, producing a single colored image that the main objective projected onto the screen.
As for the film material, according to the inventor, the fineness of grain and the resolution of the new panchromatic emulsions were able to guarantee a good reproduction even for images of only one quarter of a frame, withstanding a magnification four times higher than normal during projection without significant loss of quality.
Cristiani’s argumentation about the advantages of his system can be summarized in four points: a) the use of a normal camera with the application of the special optical group; b) development and printing in black and white that could be performed in any laboratory; c) recourse to Italian technical personnel; d) an acceptable increase in costs compared to black and white, estimated at 20-30%.
Pierotti, Federico (2016): Un’archeologia del colore nel cinema italiano. Dal Technicolor ad Antonioni. Pisa: Edizioni ETS, p. 102-103. (In Italian)
Translated and adapted by Noemi Daugaard, SNSF Film Colors. Technologies, Cultures, Institutions.
Original Technical Papers and Primary Sources
Cristiani, Luigi (1935): Cinematografia a colori naturali. Quadricromia per sintesi additiva. Voghera-Milano: Boriotti e Zolla. (in Italian)
Pierotti, Federico (2004): Il bel colore in cinematografia. Breve storia del sistema Cristiani-Mascarini, in Annali del Dipartimento di Storia delle Arti e dello Spettacolo, 2004,5, pp. 153- 182. (In Italian)
Pierotti, Federico (2016): Un’archeologia del colore nel cinema italiano. Dal Technicolor ad Antonioni. Pisa: Edizioni ETS, on pp. 69–77and on pp. 102–103. (in Italian)