660 HANDBOOK OF PHOTOGRAPHY 



obtained of a quality superior to that of the other screen plates and film on the market. 



The only disadvantage of the Finlay process is in the fact that the individual color 

 elements are fairly coarse, equivalent to about a 175-line half-tone screen. 



With the Dufaycolor film, Lumiere Autochrome plate and Filmcolor and the Agfa 

 color plate, a slight degree of enlargement in reproduction is permissible before the 

 broken-up structure of the image begins to show up. With the Finlay process, how- 

 ever, this is not permissible as the 175-luie half-tone dot formation is just small enough 

 to be invisible when viewed at normal distance, but any slight enlargement would 

 show up the screen immediately. 



The processing of both the negative and positive plates for the Finlay process is 

 best carried out in the developers recommended by both the Eastman and Ilford com- 

 panies for their negative and positive material. 



Color Cinematography. — The successful production of color transparencies by 

 both the additive and subtractive processes has led to a great variety of attempts 

 to apply these processes to motion-picture photography. The degree of success along 

 this line of activity has been rather limited. 



While the additive process is in itself the simplest, from the laboratory standpoint, 

 since the film does not need to be colored, it is nevertheless the least successful from the 

 standpoint of photographic and projection requirements. The reason lies with the 

 difficulty of producing three separate images side by side through the same optical 

 system free of parallax, which is unavoidable in multiple optical combinations. Simi- 

 lar optical systems must be also employed in projection, which means low light 

 efficiency caused by the necessity of splitting up the total light source into three differ- 

 ent components, each of which must be intercepted by the necessary primary 

 filter. 



The various optical systems schemed out for the additive synthesis do not lend 

 themselves readily to the projection of ordinary black and white. This means that 

 the optical system must be changed during the transition period from color-additive 

 projection to standard black-and-white projection. As a matter of fact successful 

 optical systems which permit obtaining simultaneously three sharp images without 

 parallax and within the narrow space demanded bj' the internal arrangement of a 

 motion-picture camera, and also suitable for projection are not available as yet. 

 Other systems which involve running both the camera and projector at a double or 

 triple speed by arranging the three-color-separation negatives and positives one after 

 the other, are not practical, because they demand duplicate apparatus in theaters, 

 unless such color systems could be universally adopted and made to supplant com- 

 pletely black-and-white projection. 



Possibly the attempt nearest to success has been bj^ means of the Dufaycolor film, 

 which can be exposed through the ordinary camera and projected through the standard 

 projector, except that in this case also, an adequate amount of light on the screen can 

 only be obtained by both powerful arc lights and extremely thin positive fUms. 

 Within this class can also be included the lenticular type of film, based on the Keller- 

 Dorian and Berthon patents, with the exception that this film needs an additional 

 projection filter, which, of course, could be easily swung in position in front of the 

 projection lens when required. 



Most successful have been subtractive processes in which the color positive is 

 produced either by dye transfer or by combination of chemical toning, dye toning, and 

 dye transfer. 



The Technicolor process, '^ which really is the only one being used to any great 

 extent today, is based solely on the dye-transfer method by means of wash-off relief 

 matrices. The three-color separation negatives of Technicolor are produced by a 



1 Ball, I. A., The Technicolor Process, J. Soc. Motion Picture Engrs., August, 1935, No. 2, p. 127. 



