International projectionist (Jan 1959-Dec 1960)

source of both projectors is tungsten. An approximate correction can be made in this case by filtering the projected light from the 35-mm viewing machine. Eastman Kodak suggests that a print originally color-timed for arc light projection, but projected with a tungsten source, can be corrected approximately with a combination of a Kodak Wratten filter No. 78B and a Kodak compensating filter CC-05G. A print which was originally color-timed for tungsten projection but projected with arc light may be corrected approximately with a combination of a Kodak Wratten filter No. 86A and a Kodak compensating filter CC-05M. Projection Services All of the equipment thus far described is basically used for quality control. In addition to quality control, the next important function of the Projection Department is to provide services for the convenience of Laboratory customers. General provides these projection services: (1) Projection of 35-mm or 16-mm television or screen prints. (2) Closed-circuit television viewing of 35-mm or 16-mm TV commercials, pilots and shows. (3) Trade or press showings at any aspect ratio for theatrical pictures. (4) Editorial or cutting screenings with silent picture, or with composite track or with separate optical or magnetic tracks. (5) High-speed inspection of stock or cut picture. (6) Editing, pre-scoring or pre-dubbing screenings with as many as four separate optical or magnetic tracks. (7) 16-mm trade or press screenings. Complete Screening Room A multi-purpose installation is shown in Fig. 3. A pair of Simplex X-L projector mechanisms with Magnarc lamps, Simplex soundheads and Altec sound and auxiliary equipment provide the usual screening services. Two sound track reproducers, an electrical interlock system, and a mixing rack in the auditorium make possible the screening of a picture with as many as four separate optical or magnetic sound tracks. Such an installation is of great value to the film editor or producer. In a Western, for example, there may be a dialogue track, a gunshot track, a FIGURE 5 hoofbeat track and an Indian warwhoop track. The editor has cut these tracks and spliced in the leader so that the effects and dialogue occur at the proper time to be in synchronism with the picture. All these tracks and the picture are threaded on start marks put on by the editor, and all pieces of equipment are rolled simultaneously by means of electrically-interlocked motors. Should any track be out of sync or cued improperly, the mistake can be remedied before the "dubbing" session at the recording studio, when all tracks are recorded together in a composite track. A delay during dubbing involves tying up highly paid recording crews and expensive equipment. This predubbing service has proved to be very popular with General's customers. A projector and a sound reproducer set up to run in interlock are shown in Fig. 4. Note the control above the sight box. It operates a variable diaphragm or vane in the light beam which varies screen brightness so that pictures of any aspect ratio can be projected at the Academy standard brightness level. A high-speed silent projector which operates at 265 feet per minute, and a 16-mm arc projector share a third port in this room. These units are mounted on casters and all service is plug-in. The 16-mm arc projector uses the existing Altec sound system and horns. Television Film Equipment A modern film processing laboratory would not be complete without means of viewing films made for television on a television tube. General's equipment includes two complete closedcircuit TV film chains. When discussing the projection of motion pictures into a TV camera for televising, the term "field" frequency is used rather than the more familiar "frame" frequency reference in motion pictures. The number of "fields" or flashes of picture projected per second is the "field" frequency per second. Sound motion picture speed is usually referred to as 24 frames per second. To refer to fields in this instance would be awkward. A two-blade shutter making 24 revolutions per second would result in a field frequency of 48. A three-blade shutter would have a field frequency of 72 fields per second. Television engineers, in the beginning, chose 60 fields per second as a field frequency for TV because synchronizing circuits could then be "locked-in" by utilizing the 60-cycle power line frequency most commonly used in the United States. Obviously, a standard sound projector operating with a field frequency of 48 or 72 cannot be used to project into a TV camera operating at 60 fields per second. The result is shutter bars or black belts across the picture. If the projector was to be operated at 30 frames per second, the field frequency (using a two-blade shutter) would be 60 fields, and would lock in with the camera frequency. But, of course, with sound recorded at 24 frames per second this is not the solution. The problem then, is how to operate at 24 frames per second and project a picture at 60 fields per second, or an even multiple thereof. Figure 5 is a view of the closedcircuit TV film chain section. The 35mm projector to the left in the picture uses the ingenious "2-3, 2-3" roller pin intermittent movement. This movement holds every other frame in the aperture one-third longer in time than the preceding one. The two-blade shutter operating at 30 revolutions per second, (Continued on page 20) 12 INTERNATIONAL PROJECTIONIST • SEPTEMBER 1959