American cinematographer (Jan-Dec 1932)

36 American Cinematographer • October 1932 AMATEUR SECTION Sound on 16 mm. Film Continued from Page 33 a satisfactory picture of the dimensions proposed. It will normally happen that the original 35 mm. negative from which it is desired to obtain a 16 mm. print will be a sound picture negative, because of a desire to use the same subject for 35 mm. applications. In such a negative, the picture is displaced to one side of the film to accommodate the sound track, and there are substantial spaces between successive frames. Consequently, it is impossible to use such a negative in a running reduction printer to produce the film layout shown in Fig 2; since it would, in fact, produce precisely the arrangement shown in Fig. 1 . This is due to the requirements of all such printers that the mechanical motion of the films and optical motion of the images must exactly correspond. If, on the other hand, the original negative is placed in a step reduction printer and the optical ratio is changed to "blow-up" the picture to the size shown in Fig. 2, the negative will be subjected to the dangerous wear and tear imposed by such printers. It is necessary, therefore, to make a duplicate negative of the picture whenever any considerable number of prints are required; and when step printers are used, a number of such negatives will be necessary to accommodate production on any considerable scale. In contrast to these difficulties, the layout of Fig. 1 affords the greatest of ease and flexibility in production. A single printer may be used for either sound or picture; and, in the case of combination negatives, for both. It is ready at a moment's notice to produce a sound, picture, or combination print from the original negatives without the delays attendant upon duping and re-recording. The method may be applied with equal facility to any number of prints, whether one, a dozen, or several hundred, with quite negligible depreciation of the negatives. In practice it has been found possible to operate such a printer at speeds as high as 60 feet per minute of 35 mm. film, and speeds of 90 feet or more may be expected. In consequence, the number of such machines required to equip a film laboratory for quantity production will be very small and a capital investment may be held at a minimum. The projection problems surrounding the two types of film under discussion present similar comparisons. Most users of 16 mm. film are familiar with the tearing of the sprocket holes that often occurs when operating ordinary silent 16 mm. projectors, and considerable doubt exists as to whether a single row of sprocket holes could be expected to endure under the even higher projection speeds required for sound film operation on 16 mm. In 35 mm. film, 8 sprocket holes per frame are employed, and the film is handled by skilled operators. Under such conditions satisfactory film life may be expected; but there is a vast difference between these conditions and those that the 16 mm. film will encounter in home, school, and office, where the equipment must be operated by persons not necessarily mechanically inclined, and the provision of only one sprocket hole per frame seems very dangerous. The difficulty of mechanically supporting film of the type shown in Fig. 2 without scratching the sound track area has already been mentioned. In contrast, the layout of Fig. I provides ample support on either side of the film. It is often desirable to arrange a machine for alternate use with translucent and reflection screens, and with the film of Fig. 1 the required picture inversion may be accomplished by reversing the film in the gate. With the film of Fig. 2 this is obviously impossible, as the sprocket teeth would then engage the portion occupied by the sound track, with disastrous effect on the latter. For such a film, the needful inversion must be effected by a relatively expensive optical device. As in the case of sound track width, the somewhat smaller picture area available in Fig. 1 is of considsrably less importance than appears from first observation. With a given subject and identical film stock, the pictures resulting from these two diagrams may present discoverable but by no means serious differences. Current developments in finer grained emulsions by this organization and others may soon be expected to yield picture quality which is beyond reproach in either diagram, 1 or 2. Projectors designed to accommodate either of these sound films are also capable of projecting any existing silent films that the owner may have in his library. In the case of Fig. 1 a lever is provided to change the aperture size from sound to silent dimensions, as desired. The design of suitable machines to project 16 mm. sound films is perhaps as interesting a development as that of producing the film itself. When 35 mm. sound-on-film was first introduced in the theatre, no attempt was made to replace the original picture projector, but instead, the sound reproducing means was provided as an attachment to the picture projector. The considerable dimensions of the 35 mm. film, and the fact that one or two makes of 35 mm. projector comprised the bulk of the field, made this arrangement feasible. In the 16 mm. field, however, the problem was quite different, for the dimensions of the film are small, the number of different makes of projectors EVERYTHING PHOTOGRAPHIC ^ for Professional and Amateur New and used. Bought, sold, rented and repaired. Camera Silencing. 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