Journal of the Society of Motion Picture and Television Engineers (1950-1954)

a test film could not be produced until a method of direct calibration could be evolved. This has been accomplished, and the Society will presently be circulating several of these films to the various equipment manufacturers for their use in establishing the frequency-response characteristics of the various magnetic sound projectors. This film will be made available through the Society's test film production activities. 2. Speed steadiness film (flutter test film). This test film is essential for the evaluation of projector film speed steadiness at the point at which magnetic soundtrack scanning is accomplished. Specifications have been prepared for its production. 3. Azimuth film. Magnetic sound on film is produced by moving the film over a magnetic gap of very small length. This gap must be aligned at right angles to the edge of the film within a very close tolerance. Each projector should be aligned from accurate standard azimuth film in order that the high-frequency end of the audio spectrum may be reproduced well by projectors other than that on which the film is originally recorded. Production of such a film is essential before anything other than the dictating-machine concept is practicable. Two types of such film have been authorized by the Society's Sound Committee. Type A: 7000-cycle film accurately positioned to within three (3) minutes of arc with respect to a line perpendicular (90°) to the edge of the film. Used basically for magnetic head alignment in projectors. Type B: 7000-cycle film, multiazimuth and off-azimuth film, produced to check the accuracy of the azimuth setting of magnetic heads in projectors. This will be a service test film used for locating trouble; whereas the type A, azimuth film, is a production tool used for the alignment of magnetic heads. Both of these films are to be produced and issued by the Society as rapidly as the production technique involved can be solved. 4. Buzz-track film. This is essential in the correct positioning of magnetic heads with respect to the magnetic track. This test film is still awaiting a solution as to its fabrication. The exact method of producing such a film has not been determined as yet and Society action will have to await a practical proposal to accomplish the desired end result. This problem is now being considered by the Society's Magnetic Sound Subcommittee. An estimate cannot be made at this time as to the film's availability. 5. Magnetic head contact film. Magnetic heads are aligned in contact with the film, at this time, by a process of applying machinists bluing to the magnetic head and adjusting the head so that the bluing is wiped off the gap face uniformly across the head width. This is an extremely laborious operation. Alignment film for field service will have to be produced to meet this need. No recommendation for such a film has been made as yet, and the problem may be left to the individual manufacturers to solve, since the film will be a production service tool and does not pertain to basic magnetic track quality testing. It will be apparent from the preceding that the establishment of quality standards and the producing of test films to measure those standards is quite a project. The situation might be summed up this way, which goes first, the cart or the horse. Applying this old clich6 to the current situation, without the pioneering spirit exhibited by a few of the equipment manufacturers the need would not exist for the Society's standardization activities with respect to magnetic sound. Therefore, since 16mm magnetic sound track is so recent it is understandable that so many pertinent engineering factors have not been reduced to common understandings through standards. The writer can, however, report that E. W. D'Arcy: Standardization Needs 529