Projection engineering (Jan-Dec 1931)

Page 20 PROJECTION ENGINEERING (7) They should consult the schedule of performances, noting particularly any deviation from previous schedules ; consult the bulletin board for information or cues left by other members of the projection staff; clean interior of lamps, arc contacts, reflectors, condensers, objective lenses, and fader; and examine arc leads for corrosion and test connections for tightness. (8) They should lubricate the projectors and let them run for several minutes, noting whether they maintain an even speed of ninety feet per minute; stop projectors, clean film trap, sprockets, and fire rollers, and wipe excess oil from bearings to prevent accumulating oil on film; check projector mechanisms for proper tension of pads, for proper clearances of pad rollers, fire valves, and film trap, and for tightness of all set screws of connectors. (9) They should then check the exciting lamps for discoloration, condition of filament, and proper line-up ; see that the sound optical system is free of oil ; rewind and examine film. If new program, rewind and examine film prior to first showing, observe if changeover marks are properly placed and if any defect, such as oil accumulations, scratches, buckling, strained or broken sprocket holes are apparent. Such defects should be reported immediately. (10) Such parts of projection and sound equipment as do not require daily cleaning, lubricating, or inspecting should have a designated day of the week assigned for receiving such attention. (11) The procedure as outlined above, if properly carried out, will guard against film damage. Faulty adjustments or worn parts will cause film damage — a cause of great loss to the industry. Film in bad condition, faulty adjustments, or worn mechanisms create possibilities of film fire, with its attendant danger and financial loss. (12) In projecting picture or effect, the projectionist should strive to avoid imposing any distraction on the audience which would serve to destroy the illusion, such as flickering light, shaking or moving the projected image. (13) He should be constantly alert in maintaining even illumination, sharp focus, smooth changeovers, and proper timing of opening and closing of curtain.. He should fade the picture or effect on and off gradually, to convey an agreeable and smooth effect to the audience. ■ (14) He should be stationed constantly at the projector while it is in operation, and should be promptly responsive to signals for adjustment of volume. (15) Where the control of the cur tain is not directly handled from the projection room, a pre-arranged system of warning and closing signals should be used. Such signals usually consist of a two-buzz warning to the stage which is acknowledged on a return buzzer. A one-buzz signal is given at the moment of opening or closing of curtains or changing screen masking for various-sized pictures. (16) Film should be examined after each run and checked for loose splices and scratches, and if oil has accumulated on the film, it should be wiped off and the projectors checked immediately to eliminate further scratching. Projectors also should be wiped dry of oil after each reel and checked for accumulations of emulsion from the film. (17) Where more than one projectionist is on duty and when a projector has been threaded, the arc trimmed and fully prepared for the showing of each succeeding reel, the projectionist completing this work should step to the running projector and relieve the other projectionist, to allow him to check each detail of threading and trimming, noting that the proper reel has been placed in the projector. This routine of checking should be firmly established in the projection room as it has been the means of discovering faulty threading and incorrect reels in time to make corrections and avoid interruptions or film damage without making such errors evident to the audience. (18) A minimum supply of spare parts should be determined upon. An accurate record of necessary spare parts and supplies should be kept by projectionists, and when items are used which reduce the amount below the minimum figure, such items should be reported in the "Supplies Needed" column of the projectionists' daily report. (19) When ordering parts, the correct technical designation and catalogue number should be given wherever possible in order to avoid error in delivery. Catalogues of main items of equipment should be filed in the projection room for reference. Parts subject to breakage, such as gears, vacuum tubes, and connectors, should be distinguished from parts which are subject to gradual wear, and additional precautions should be taken to provide against emergencies arising through such breakage. (20) To provide against accidental breakage of spare vacuum tubes, they should be stored in their individual boxes. Tubes, as well as other spare parts, should be further protected by being placed in a large metal cabinet containing shelves and equipped with a lock and key. This manner of storing will facilitate a rapid inventory checking of spare parts. (21) Proper attention should be given by the projectionists to the matter of maintaining the proper level of electrolyte in batteries. The avoidance of over-charging or over-discharging will result in a full useful life of the storage batteries and, conversely, a lack of such attention will result in a very greatly shortened life and subsequent waste and expense for replacement. (22) Where a generator is used in place of batteries it will be necessary to inspect the commutator each day and wipe it off with cheesecloth moistened slightly with vaseline. If this practice is regularly followed, the commutator should remain in condition for perfect sound reproduction. (23) Exhibitors should acknowledge the good work of the projectionists in maintaining the equipment in the best condition and should be willing to institute new ideas and install new appliances which contribute to better performance or increased efficiency. In conclusion, it is the belief of the committee that every owner, manager, and projectionist should take cognizance of the fact that the projectionist is in a position to contribute measureably to the advancement of the industry. Every projectionist should manifest a desire to conduct his work so that optimum screen results are efficiently secured. Systematizing the routine work in the projection room is highly important, for it is only by the orderly arrangement of the many complex details that : (1) thorough inspection, servicing, and checking of equipment can be made ; (2) equitable working arrangements, discipline, and harmonious cooperation between projectionists can be had; (3) efficient results from projection and sound apparatus obtained; (4) smoothly conducted performances secured. The foregoing is the report of the Sub-Committee on Monitoring and Control of Sound in Theatres, Society of Motion Picture Engineers, at the 1931 Hollywood meeting. ▲ BOOK REVIEW PROJECTING SOUND PICTURES. By Aaron Nadell, 265 pp., Illus., Cloth. McGraw-Hill Book Company. New York. Price, $2.50. The author is an engineer in the service of the Publix Theatres Corporation and was formerly employed by Electrical Research Products, Inc. With this practical background Mr. Nadell is qualified to write authoritatively on the subject of sound-picture projection. The book is well written and covers the design and operation of practically all modern theatre projection systems.