Projection engineering (Jan 1932-Mar 1933)

FEBRUARY, 1932 Commercial 16 mm. sound-on-fiim THERE has recently been placed on the market a new 16 mm. sound-on-film process, under which process the sound track is printed alongside the picture exactly as with 35 mm. and is in every respect an exact miniature of the standard 35 mm. sound-on-film. The film used is standard 16 mm. film, runs at 36 feet a minute, uses both sets of sprocket holes, has 40 frames to the foot, projects 1,440 pictures upon the screen a minute, has a sound track whose width is twenty thousandths of an inch running alongside picture — interposed directly between picture and perforation— (exactly as in 35 mm.) and reproduces voice and music with all fidelity, clearness and volume of its larger brother the 35 mm. It has been determined that the following principles must be adhered to strictly, basing the following outstanding points wholly on commercial considerations ; limitations considered necessary if the 16 mm. talking motion picture is to be commercially successful. 1. Nothing but standard 16 mm. film must be employed, and sound-on-film, and not disc, must be employed. 2. That a double set of perforations must be retained, and no split frames allowed. 3. That the sound track must be photographed on the film exactly as is done in 35 mm. and that sound track must not take away from the picture more picture space than the 35 mm. sound, or namely, not to exceed fortyfive thousandths (.045 inch) of an inch in width. 4. That the sound track must be capable of reproducing all frequencies found in 35 mm. recording with as fine a fidelity, clearness and volume as the 35 mm. 5. That the speed of the film must be legulated to run at 36 feet per minute, which would give exactly the same number of frames (pictures), namely, 1,440 per minute as in the 35 mm. film. 6. That all pictures to be photographed must be taken on 35 mm. and means of optically reducing to 16 mm. be perfected, that sharpness of detail Description of a new 16 mm. sound-picture system using sound-on-film and reduction of film grain be obtained to allow for commercial projection of 16 mm. pictures upon a sufficiently large screen in auditoriums, seating at least 300 to 400 persons, so that all present can see the picture clearly and without eye strain. 7. That the recording process and apparatus must be so refined and commercialized that trained operators can consistently turn out the highest standard of work, both in studios and trucks. 8. That simple, well-made, sturdy projection must be perfected, together with suitable amplifying apparatus which would, in the hands of careful persons, project both sound and picture consistently, and give satisfactory results, under the most difficult and trying conditions. 9. That the price of apparatus and equipment must be kept down to reasonable figures, so that schools, churches, clubs, and other educational, industrial and amusement interests may become a ready market for the 16 mm. picture. Development Retaining both sets of sprocket holes, while requiring much additional work to develop the sound track with such small dimensions as to keep within the required .045 inch width, has proven sound. Where only one set of sprocket holes is used the wear and tear on film in projection shortens life of print to a point which makes single sprocket film impractical and non-commercial. Should the split-frame method have been adopted, the wear and tear on film would have been tremendous, and while by printing split-frame pictures, i. e., wherein a blank space, the size of one picture is left out after each picture frame, 1,440 frames of pictures would have been retained, and, in addition, would have 1,440 blank frames spaced alternating with the picture, thereby giving 72 feet a minute surface speed of film for the sound track. The desired commercial advantage might not have been gained inasmuch as twice the correct amount of film would have been required with the additional double cost of film as well as the breakage factor of pulling the film two frames in place of one. The three-dimensional sound track which track has, together with the de Page 17 velopment of a new process of photographing the sound variations, made it possible to re< ord all harmonics and music usually recorded where 35 mm. is used, within as small a width track as ten one-thousandths (.010 inch) of an inch, whereas the standard 35 mm. sound track, measures one-tenth CI 00 inch) inch, or ten times as wide as the smallest 16 mm. track. Manufacturers have standardized the 16 mm. sound track with a width of twenty thousandths (.020 inch; of an inch, with the reproducing aperture set at fifteen thousandths (".015 inch) of an inch, thereby allowing for (.0025 inch) 2j^ thousandths of an inch cutoff, which makes the 16 mm. sound track one-fifth the width of standard 35 mm. track. In the development of the 16 mm. sound track it has been possible to retain the pureness of and clearness and volume of the 35 mm. sound film, in every respect. The reason for standardizing 16 mm. film, so that it should run at thirty-six feet per minute, or 1,440 frames, was due to the fact that a great portion of all 16 mm. film for a long time to come will be taken from 35 mm. pictures already made, and all 35 mm. film is photographed and projected, today, at a speed of ninety feet per minute, which means that 1,440 frames of pictures will pass the projection lens each minute. In 16 mm. there are forty (40) frames of picture to each foot of film, and so, when running at thirty-six feet per minute, we have 1,440 frames passing the aperture each minute. It is well known in the art that, optically-reduced 35 mm. to 16 mm. pictures give prints of far greater sharpness, detail and finer grain, than contact prints, and by using frame for frame, a 900 foot reel of 35 mm. (having 16 pictures to the foot and 1.440 frames to 90 feet) will optically reduce to 360 feet, on 16 mm. It remains only to record the sound track upon 360 foot of positive 16 mm. film to match for contact printing with the optically-reduced 35 mm. picture. In the case where sound has been recorded on 35 mm. film, the picture is optically reduced, frame for frame, and the sound track picked up — inputted through pre-amplifiers, through recording amplifier and re-recorded at 36 feet per minute on 16 mm. film. In the case of synchronized discs — pictures are optically reduced as above, while sound is picked up from 3>i 1/3 r.p.m. turntable, inputted through recording amplifier and re-recorded at 36 feet per minute on 16 mm. film. Where direct picture is being photographed and sound recorded over microphones, or pickups, or both, the picture is short or photographed on 35 mm. film, which runs at the standard speed of ()0 feet