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

Mr. Heacock: It's a long guide which is located in the film trap on each side of the film. In general, these are adjustable, so that if we say that a 35-mm film would be the distance between my two hands, this guide against which the edge of the film moves, is stationary. This one is ad justable, so that you adjust this guide to give you the steadiest picture possible, taking into account the variation due to shrinkage in the width of film. It is that adjustment that is generally the determining factor in lateral weave of the film in the film trap. Mr. Zambuto: I asked the question about the different sprocket holes and lateral weave. There happen to be a certain number of moments in which the lateral guides fail to be the determining factors. Most of the time, when a splice goes by, you find the lateral guide fails to be the determining factor. But I was thinking of something else. It's every body's experience that when the film is a little warped, or the perforation a little damaged, you find that the film is no1 correctly fed to the lateral guide. In such irregular feeding the tooth may easily become the limiting factor, by determining the strain on the lateral guide. Mr. Heacock: I believe that at the instam that a film splice or some other irregularity occurs in the film trap, that the conditions may be quite unusual. But, of course that's an extremely small percentage o elapsed time and I still feel that, whethei you have the GinemaScope width of tooth or whether you have what has been oui old standard width of tooth, you will stil find that studio guides are the determining factor and it would be my guess that the situation might not be seriously differeni with the GinemaScope sprocket just foi that instant, as compared to that when the standard sprocket is used. However, any other comments will be welcome. Magnetic Head Wear — Panel Discussion JOHN G. FRAYNE, Moderator Editorial Note: "Ferrite-Core Heads for Magnetic Recording" by R. J. Youngquist and W. W. Wetzel, presented at the same Convention session as this discussion on magnetic head wear, has not been released for publication. The tentative conclusions put forth at the Convention have been withdrawn because continuing tests on ferrite-core heads have not borne out the earlier hopes. At the end of the discussion, Dr. Frayne called for all concerned to add data when they received the draft of the discussion transcript. Edward S. Seeley (Altec Service Corp.}: First, who has seen operational or performance evidence of head wear; and second, what has been the nature of the performance change as a result of wear? This discussion was held on October 9, 1953, at the Society's Convention at New York, with John G. Frayne as Moderator. John G. Frayne ( Westrex Corp. ) : I have seen physical evidence of head wear. Mr. Seeley: How about performance evidence? Dr. Frayne: Yes, we have noticed change in performance, particularly with respect tc high-frequency response and erratic contact. 1 have no exact figures, but that we have head wear cannot be questioned. Ii is our estimate that with Westrex magnetic heads used in studio recording and reproducing equipment we obtained somewhere between 3,000,000 and 5,000,000 ft o wear without any serious changes in characteristics. R. H. Heacock (RCA Victor Div., Camden N.J.): We have one actual operating theater experience that was of interest tc us. This was in the first installations ol double-film systems that were made with 238 March 1954 Journal of the SMPTE Vol. 62