ANIMATED CARTOONS the figure may be dispensed with and the slit itself placed very close to the film. In fig. 6, Pl. XIII, is shown an example of a motion picture positive film with the accompanying photographic sound track record at one edge. (C. E. K. M.; NA. L.) Projection Background Photography.—Great savings in motion picture production are made by means of projection back ground photography. The desired scenic background is photo graphed by a motion picture camera. This is then projected by means of special projectors onto a translucent cellulose acetate screen. The actors are placed in a set in front of this projected motion picture and photographed. Thus, they are photographed in the desired setting without the necessity of transporting them and the complicated equipment to the location. The camera, the pro jector, and the sound recording machine are electrically inter locked so that they rotate in exact synchronism. This insures that the shutter of the camera and the shutter of the projector move together, as otherwise the shutter on the camera might be open, and the shutter on the projector might be closed, so that the scene would be photographed without any scenic background.
Most of the unusual photographic effects seen on a motion pic ture screen are the result of optical printing. Optical printing is
a process of rephotographing at approximately unit magnification from one motion picture film to another. The equipment consists essentially of a camera and a printer facing each other on a lathe bed and driven in synchronism.
The original picture can be modified in many ways with this equipment.
The intricate transitions of "wipe offs" seen so often in motion pictures are made by interposing movable mattes between the camera and printer. Frames of the picture can be eliminated or repeated. Stationary or moving clouds can be inserted in outdoor scenes by multiple exposures. Any type of fade, dissolve, or "split screen" shot can be made. The printer can be rocked slightly, giving the correct impression of motion to boat and aero plane interiors made on a stage.
Scenes whose costs would be prohibitive are often reproduced in miniature. Naval battles are fought and entire cities are de stroyed in a very realistic manner by this means. They are usually complete in the greatest detail, all of the miniature figures in the setting being moved electrically so that when photographed they present a perfect illusion.