International projectionist (Oct 1931-Sept 1933)

24 INTERNATIONAL PROJECTIONIST July-August 1933 TRAILEREEL "THE HANDIEST THING IN THE PROJECTION ROOM' FOR WINDING TRAILERS, ETC., FOR SHIPMENT CAST ALUMINUM PRICE ACCURATELY MACHINED $1.00 Try It 10 Days— We Will Refund Your Money If You Want It. MADE BY TRAILEREEL MFG. p. O. BOX 35 EAST HARTFORD. CONN. such schemes would be workable if every theatre always ran first-run film. The number of theatres that run firstrun film are a small minority. But what will happen in the theatre that receives 30 or 60 or 90-day films, and sometimes 200-day films, in which case one is particularly lucky if he has the last scene in at all. How will the actuating device for the photoelectric cell work then? So many different kinds of marks appear on film that it would be almost impossible to place a mark that would not be duplicated several times throughout the run of the film by accidental marks made by faulty equipment. Mr. Kurlander: The value of the travel-gTTost pattern rests on the fact that when no travel-ghost is present, a pattern is seen; and if travel-ghost is present the pattern is thereby changed. It is true that the projection distance will determine what the width of those lines should be. That is a point the Committee should investigate. The pattern, however, was advanced with the idea of detecting a very small change or increase in travel-ghost. With respect to photoelectric cells, Mr. 0. H. Caldwell, in a paper presented on the first day of this convention, certainly gave enough illustrations of the work that can be done by small photoelectric cells. Mr. Finn: I am very familiar with Mr. Caldwell's paper. I still maintain, however, that the fact that a photoelectric cell, or a light-sensitive cell, will operate a relay and cause a garage door to open doesn't mean that it is suitable for change-over purposes. A photoelectric cell must have some actuating means; and I insist that the film travel controls the change-over process. A mark is required on the film itself. What else is going to control the cell's operation? Mr. Schlanger: Some of the same films as, or films similar to, those used for testing projection equipment, could be advantageously used by the exhibitor to test the particular view of the screen that each seat in the theatre may aff'ord. Distortion Measurement A simple device could be used in conjunction with the test films. It would consist of a piece of glass or other transparent material, small enough to hold in the hand before the eyes. On it would be printed a pattern, similar to the pattern used in the test films, consisting of a series of horizontal lines in one case, and vertical lines in another. By looking through this glass frame at the test film projected on the screen, the amount of distortion of the screen image from any seat in a theatre could be measured. Such a testing method is intended chiefly for use in existing theatres having seating arrangements in need of correction to obtain a proper view of the screen. If such a device accompanied the test films distributed to exhibitors, and should the exhibitors themselves witness the distortion of the screen image as seen from the poor seats, they might show more interest in improving the sight lines of their theatres. Member: The accuracy or value of the optical alignment tool depends entirley upon the straightness of the rods. I wonder whether they might not become bent during use without being noticed; and whether a certain degree of springing might not occur — so that when the test is made, it might be thought that the system is faulty, \v-hen it isn't. I would suggest the use of tubes instead of lods, with the idea that one might sight through the tubes and correct the tilignment that way. If the tubes were bent, it would be noticeable. And 1 believe also that by that method it should be possible to make the alignment with only one setting instead of two, as are necessary in the case of a rod. A light would be placed at the end of the tube in the projection head and one would sight through the tube in the lamp house. Mr. Rubin: This tool is made of steel that can't be bent without great difficulty. Mr. Kroesen: Many tests should be made before the rod is finally adopted, because there are too many variances throughout the projector mechanism to warrant our saying it is accurate without testing it sufficiently. Many manufacturing tolerances should be taken into consideration. Mr. Jones: The manufacturers of projector lenses certainly have during the past years given the subject of testing those lenses a great deal of careful study. I am quite sure that they have worked out tests that have proved satisfactory for detecting the various kinds of aberration; and I am wondering whether they have been consulted with regard to the various test objects that are adapted to show with the maximum of magnification these various defects that we wish to locate. If not, I certainly think that before we decide to adopt any particular test film, the matter ajiould be discussed with them. The Committee Viewpoint Mr. Rubin : The purpose of the Committee has been to design or suggest, a set of tools for the projectionist that would be simple and easy to use, without requiring the assistance of specially trained engineers. Up to the present time, the projectionist has not been provided with any tools with which to test his equipment. He has not been encouraged by any society, to provide himself with such tools. The Projection Practice Committee has attempted to do so. The tools — the test film and the alignment tool — have been so designed as to require no special training on the part of those who use them, to require a minimum of time in which to conduct the tests, and to require no additional equipment whatever. Perhaps these tools can be improved; I am sure that the optical companies have better testing equipment, but it is probably more elaborate. For many years projectionists used titles for testing for travel-ghost. Since the inception of sound and the absence of titles, he has had to substitute something for the title, and has found that any vertical sharp point against a black background, or a white spot against a black background, will be the best test for travel-ghost. In the present design the sharp points against the black background are easily visible, and provide the best means for accurately correcting the travelghost. Both fine lines and heavy lines are provided, and you will notice that the sharp lines show the travel-ghost #