Amateur Cine World (June 1934)

Vitacolour system is scarcely a_ practical proposition, but the prize-winning film was nevertheless a_ great achievement. One of the simplest colour processes so far as the amateur is concerned is the “Kodacolor” which reproduces in natural colours pictures taken with the cine camera. If you examine a strip of ‘‘Kodacolor”’ film you will find that it is black and white and there is nothing to distinguish it from ordinary film except that at the back of it there is a myriad of small embossed ridges, which in practice act as the means of recording and reproducing in colours. The film is used in both camera and projection with the emulsion side away from the lens and the embossed side nearest the lens, so that the light from the lens strikes the back of the film first. The ‘ Kodacolor’’ System. The Kodacolor system depends primarily on the fact that red, green and blue-violet light together make white and hence any colour can be produced by blending these colours in the correct proportions. A special tricoloured filter must be fitted to the camera when taking pictures in “ Kodacolor”’ and owing to the density of this filter the camera must be fitted with an f/1.9 lens. The small ridges on the film to which reference has already been made act as a series of small lenses which CAPTURING COLOUR IN CINE FILMS (Continued from page 114) transmit the light on to the emulsion after the light has been filtered by the tricolour filter and focussed (as in all cameras) by the main lens. These small lens elements, of which there are 559 to the square inch, throw the light on to the sensitive emulsion as a series of parallel lines, each of which represents a portion of light which has passed through one segment of the filter. Hence, if we are going to film someone wearing a blue hat and red dress and holding a newspaper the reflected light from the hat will pass only through the blue segment of the filter on to the film. Similarly, the red light from the dress will make an impression on the film emulsion after it has passed through the red section of the colour filter; the newspaper, however, will be recorded on an entirely different system, for each segment of the filter will gather a certain amount of reflected light from it since the white colour of the paper is composed of a portion of red, blue and green light and it will be recorded on the film as three parallel lines with each tiny lens. After Processing. When the ‘ Kodacolor’’ film has been processed it will appear as an ordinary black and white positive (and can be printed as such), yet under the microscope it will be found that a series of elongated lines are apparent on the emulsion side of the film. Thus in the subject referred to above, the newspaper will appear on the print as a series of three transparent lines which are the photographic images of the light passed by the red, blue and green portions of the filter; while the blue hat will be composed of one line photographed by the light transmitted. by the blue section’ of the colour filter. Similarly with the other colours. Any intermediary colours will be produced as a combination of either two or three of the foregoing and will vary in density with the shades of the original. When “Kodacolor’’ film is projected a filter very similar to that used on the camera for taking pictures is affixed to the. projector and the picture is built up in natural colours on the screen. The film is ‘backed’ like all modern films with anti-halo backing but this disappears during development. Colour on 9.5 mm. Stock 2 The ‘ Kodacolor’”’ process, unfortunately, does not allow of copies of the film being taken and it is only for this reason that an otherwise excellent colour arrangement has not been adopted in the professional field. A similar film to the ‘‘ Kodacolor’’ is the ‘‘ Agfa-color ”’ film, which works on the same system and produces similar results. In the 9.5mm. and 8mm. field no colour system has yet been evolved and there is a definite market for some manufacturer or individual who can produce a colour arrangement for this size of stock. Whatever it may be let us hope there will be no necessity for extra fast lens and special filters and that it will be sold at a reasonable price. Details of the new Spicer-Dufay colour system will be found on page 111. This system, one of the simplest yet, does not involve the use of heavy density filters or fast lenses. A shot of this kind would look particularly effective through the blue section of a colour wheel. 126