Principles of cinematography : a handbook of motion picture technology (1953)

GENERAL TRENDS AND RECENT INVENTIONS 437 A new length of negative film is then threaded into the camera head of the Optical Printer and together with it is loaded the final contrasty duplicate negative (that is, the film in which the carpet is absolutely black and the background is transparent). The original correctly exposed master positive of the background scene is then threaded in the printing head of the machine and the optical system is adjusted to give a one-to-one copy. As the printer goes into operation the background will only be exposed through the contrasty matt and only over those areas of the new duplicate negative stock which are not covered by the opaque area in that matt and which, of course, correspond to the original picture of the magic carpet. The correctly exposed master positive of the background scene is then removed from the printing head and is replaced by the original correctly exposed master positive of the carpet and its passengers. The composite duplicate negative which is in the course of production is then rewound and is threaded through the machine in contact with the final contrasty positive copy of the carpet shot (that is, the film in which the carpet is perfectly transparent but the background is absolutely opaque). This opaque background will now protect those areas of the new composite duplicate negative which have been previously exposed. The transparent 'window' in this new matt will now reveal those unexposed sections of the new duplicate and onto which may be printed the correctly exposed images of the carpet and its passengers. Since the scene is to be produced in Technicolor it will be apparent that a Technicolor camera head must be used in the Optical Printer and, since this colour process requires two film gates, one to contain a single film and the other a bi-pack, it is more usual to thread the travelling matts in contact with the correctly exposed prints in the head at the opposite end of the machine. Obviously, it is necessary to very carefully mark the 'start' frame on each negative, matt, positive copy and final composite negative, to ensure accurate synchronisation. Hie success of this process is largely controlled by the accuracy of the mechanism and also of the film perforations. It is usual to find a very narrow black fringe around the edge of the composite picture but, instead of reducing the effect, this is thought by many to improve the appearance and to add to the illusion by causing the centre of interest to stand out in relief. (c) The Addition of Clouds to Exterior Shots. A very recent process has been introduced to provide clouds in exterior scenes which must be 'taken' on a cloudless day. Such work is mainly of interest to the American Studios, where weeks of cloudless sky are not uncommon. The system consists essentially of an extended matt box, located some 18-inches (45-7-cms) infront of the camera lens, and capable of holding a glass plate of suitable dimensions. The glass plate carries a positive photographic record of a suitable cloud formation, located in the upper section of the area, and transparent glass at the lower section. Obviously, the clouds do not finish in an abrupt line and it is also necessary so to mount the transparency that the original horizontal plane, which should be indicated on the edge of the plate, is lined up with the true horizon of the scene which is to be photographed. The clouds in the transparency will be printed onto the camera negative by the light from