American cinematographer (Jan-Dec 1924)

September, 1924 AMERICAN CINEMATOGRAPHER Twenty-five curs at the stop. Consideration of these points will make the curves clear. A further interesting result in the use of the 90° movement is that the required accuracy in adjustment of the tension shoes is far less than that demanded by the faster types. With the former, this attachment has little to do beyond holding the film firmly to the aperture and giving some slight braking action to the mass of the film already brought to a stop by the action of the intermittent. With the faster types, the setting of the tension shoes seems very critical, as they are called upon not only to accomplish the above but in addition must stop the whole moving film instantly as the faster intermittent, because of its design, does not effectively do this. The film is not brought gradually to a full stop but must in effect stop itself when the intermittent disengages, as may be noted from the curves. It appears also that unsteadiness of picture is more likely to result from the fast intermittent than the slow one if an operator is not especially careful in setting the tension shoes to prevent the film over-riding the aperture. If shoes are set over tight then film wear is increased with possible tearing of film and interruption to service. Adjustable Tension We have been informed that adjustable tension is necessary to compensate when using old or new film. With the slow intermittent our results have indicated satisfactory performance on all film tried with no variation in adjustment at all. With the fast types this was not the case and adjustment for new and old film was necessary. Soft new film having a higher coefficient of friction, of course required less tension on the shoes to accomplish their function as explained. Shoes set for old film tore new film, and those set for new film allowed picture jump with old. It seems then that deficiencies in design of the intermittent are compensated by adding an adjustable device which requires very critical adjustment by the operator for each kind of film run to insure entirely satisfactory service. The foregoing are some of the reasons why we feel convinced that, for our purposes, only the 90° Geneva Star and Cam will meet the requirements. This intermittent which has been previously referred to as the 1 to 1 based on ratio of star and pin circle diameters is the same as is sometimes referred to as the 1 to 3, based on the ratio of Roy Davidge Film Laboratories NEW EQUIPMENT GREATLY INCREASED FACILITIES COMPLETE COMMERCIAL PROJECTION ROOM 6701 Santa Monica Boulevard (Opposite Brulatour's) PHONE GRanite 9503 Personal Attention to All Work time of moving to the stopped periods per revolution. It is hoped no confusion will be introduced by the pharaseology used. Closely connected with the intermittent problem in the quality of projection and film life appears the sprocket design. This seems to have been pretty well worked out by the Eastman Kodak Company, on the standard film perforation, considering film shrinkage, etc. However, our tests have revealed no machine submitted which actually followed the data of the above named company in their sprocket design. The length of the arcs of film contact on the various sprockets does not seem, in general, to have received much consideration and certainly no standardization. One make only appears to have given it consideration really worth while. The more teeth in mesh the greater will be the effect of the film change through shrinkage and unless this is compensated serious film damage seems likely to result. It is hoped that the general question of intermittent design has not been too much stressed. It is not meant by this to convey the impression that many other things, such as framing, shutter design, etc. are not thought to be of great importance in efficient projection. It is only that the intermittent is believed to be of the greatest importance for our purposes. Commercially perhaps the cost of film is not greatly considered and the amount of film damage chargeable to a given design is not readily apparent. But unless film producers are running for charity, the operators must be paying the combined cost of an enormous amount of uselessly damaged film through increased film rental charges. The automobile engineer did not, in the early history of the industry, consider to any great extent tire mileage nor the effect of his design to increase or decrease it. Today it is one of the first considerations of design and one of the first questions asked by a prospective purchaser. The Navy is trying to standardize many of the machine accessories for its use at the same time. Projection distance will be standardized for the different types of ships and the size of the screen, and the lens feature and general characteristics will also be made standard. Condensers seem at the present time to be more or less in the development stage. Some recent very radical changes indicate no general fixed commercial policy concerning this feature. Machines in service are subjected to most severe changes in temperature and it is to be hoped that a suitable heat resisting glass will soon be available. The greatest advantage to be gained in a more or less complete standardization is simplicity in the stocking and distribution of spare parts and accessories to our widely separated projection stations about the seven seas and to increase the efficiency of operators and repair personnel through restriction in the number of types used. Finally it is hoped that economy in first cost and maintenance expense of machines and film will naturally follow standardized practice. mwfi HE MPSTD 8761 ■ international kinema research* L -ou Howland Hollywood Security Bldg.