International Review of Educational Cinematography (Jan-Dec 1932)

470 The problem, already in itself somewhat complicated, is now rendered still more difficult by the necessity of applying, even on the reduced size film, the sound column. Here again the solutions proposed are numerous and all represent a form of compromise between the photo-acoustic requirements and the limitations imposed by the reduced size of the film. Without going too much into details, it will suffice to mention that the proposals may be summed up in two principal systems. In one, the acoustic strip is reduced from the normal in length and breadth in proportion to the reduction of the size of the image. In the other method, the sound strip is given a greater length than in the first system, and either an empty image is interposed between two successive images (Blankfeld system), or each image is rotated at an angle of 90° so that the larger sides of each photogram run parallel and not at right angles to the film's length. It is evident that in these cases the sound strip will be longer than in the case of reduction pure and simple, with no small advantage for the reproduction of the sound. Although in this field no actual standardisation has been arrived at, it is safe to say that the experiments in the matter have resulted in great progress. A proof of this may be seen in the proposals put forward by the Jones Research Sound Products Inc. of New York and the scheme suggested by the special sub-committee of the Society of Motion Picture Engineers. The proposal made by the Jones Research people deals with the use of a sub-standard film of 16 mm representing an exact reduction of the normal 35 mm film. To maintain the standard frequency of 24 photograms per second, such reduced size film must be run at a speed of 1 1 metres a second, and projected — like standard film — at 1440 pictures a miute. The width of the sound column is 0,508 mm. According to the firm in question, the essential points which alone permit a successful use of sound films with reduced size projections are the following : 1) Exclusive use of sub-standard film with sound strip and consequent abolition of gramophone systems. 2) The film must have a double lateral perforation ; no system of alternate images as mentioned above. 3) The photo-acoustic registration must be made in a way that is perfectly identical with that used for standard film, and the sound strip must not conceal, in proportion, a section of the image greater than that concealed by the strip itself in normal films. That is to say, the width of the sound strip must not exceed mm 1.14. 4) The sound registration must be such as to produce qualitatively the same frequencies reproduced in normal pictures. 5) The speed at which the film is run must be metres 10,8 per minute, corresponding, that is, to a cadence of 24 pictures a second. 6) The original taking of the film must be made exclusively on standard film, for later reducing on to 16 mm film. This with the object of obtaining a reduction in the granulation such as to allow the projection even in halls containing between 300 and 400 spectators, without excessive enlargement liable to produce eye strain. 7) The registration processes and the machinery must be improved so to allow absolutely perfect pictures, whether taken in the studio or out of doors. 8) Improvement in the optical projections and in the sound reproduction. 9) The prices of machines and accessories should be kept within reasonable limits, so as to render them accessible to schools, communities, and educational institutes for which they are specially destined. The sub-committee nominated by the Society of Motion Picture Engineers, on the other hand, arrived at somewhat different results. The proposals of this sub-committee for the standardization of the 16 mm film deal with two types of standard film : one with double perforation and the other with lateral perforation, with the sound strip taking the place of the second perforation.