International projectionist (July-Dec 1934)

July 1934 tion of the program, systematic coordination between the production studio and the theatre can be achieved. Discussion: Mr. Sponabi.e : I received one of the first copies of the Standard test reel devised by the Projection Practice Committee, and have been using it almost constantly since the time I received it. There is an indication that the reel is gradually changing as a standard of frequency, also as a standard of sound quality. The Committee should investigate the question of how long a standard would remain a standard for frequency and speech and quality. Mr. Davee : When the films that we propose to make are calibrated, the circuits that are employed in the calibration will be in the Society's offices. Both the RCA Victor Company and the Bell Telephone Laboratories will calibrate the same film, and if a difference is found to exist between the calibrations, it will have to be eliminated. When the circuits are submitted to the Committee, it is expected that they will not differ so much as to forbid a satisfactory correlation between the two, and a standard measuring circuit will be arrived at so that -we can check the frequency of the standard film from time to time to find out whether it has deteriorated or not. We do not particularly care what that frequency characteristic is ; it can be anything, so long as we know what it is and can check it from time to time. Mr. Kellog: The calibration of such a film involves not only correction for the frequency characteristics of the electrical circuits and equipment, but complete specification of the characteristics of the optical system. The first and obvious item is the width of the scanning or slit image on the film. That is very readily defined. The next question would be the percentage of light falling within the nominal image width ; and even the distribution of light in both directions might have to be specified, especially if we are much concerned with the very high frequencies. The correction of the solid angle of collected light on the photo-cell side would probably have to be specified in order to obtain the :same ratio of scattered light to specularly transmitted light in all calibrations. Mr. Davee : Those points have already been discussed by the Sound Committee, and as soon as we have the circuits, 1 believe they will be covered. Warning1. International Projectionist has no subscription agents and participates in no group offers of either books or other magazines. The only bona fide subscriptions are those submitted directly to the publisher. Through the courtesy of Mr. F. H. Richardson we learned of an agent who is working through California and other "Western states with "combination offers" of I. P. and other magazines, or of I. P. and Richardson's Bluebook of Projection. 6th edition, "at a special bargain offer." This and any other combination offer ■of whatever character is a fake, pure and simple. I. P. has no subscription agents and anybody so representing himself is a fraud. INTERNATIONAL PROJECTIONIST PROJECTIONS By Frank Dudiak 11 WHAT is the normal fader setting? is a question which brings out not a few diversified opinions. A number of projectionists hold to the view that the lower half of the scale is the most suitable position, provided sufficient amplification is available. Others insist that a few points above the scale center is the most satisfactory position. The former group assert that the primary advantage of a lower setting is one of quick change-over; with the latter group saying that on a higher setting the possibility of overshooting is considerably lessened. Personally, we favor the latter group, and on a scale of 15 we choose 9 as a "normal" fader setting. Ionization of a gas is the process of separating electrons from neutral atoms, leaving the latter positive. Consequently, such a gas contains free negative particles and free positive particles. Now, if a negative and a positive electrode be placed in this gas, a stream of electrons will flow toward the positive, and the positively-charged atoms will flow toward the negative electrode. Like charges repel; unlike charges attract. This stream of ions constitute an electric current, although the potential in the electrodes must be very high in order to obtain this ionic effect. This, briefly, is the fundamental principle of the photoelectric cell. Have you ever stopped to consider that in running a two-hour show, 10,800 feet of film pass through the projectors, and in the process 259,200 individual pictures (frames) are projected upon the screen? On numerous occasions we receive prints that are in excellent physical condition— except for one thing: it is well covered with a mixture of oil and dirt. Also, we frequently find not a few hairs distributed over the film, held there by oil and by the attraction of static electrical charges. These hairs have a tendency, as the film passes through the projector, to lodge in the picture or sound aperture resulting in their being shown on the screen or, if not this, in sound distortion. This can occasion much grief for the old ""dome" — and it won't be dandruff, either. Just to refresh your memory you might ponder on the four accepted laws of resistance, which we pass along to you herewith : 1. The resistance of a conductor is directly proportional to its length. 2. The resistance of a conductor depends upon the material from which it is made. 3. The resistance of a conductor is inversely proportional to the area in square mils. 4. The resistance depends upon the temperature of the conductor. That black or clear horizontal line on the outer edge of the film, a comparatively recent development, can easily be utilized to determine the frame line in dark film, irrespective of whether it happens to coincide with the frame line. In the event that it does not coincide, it is only necessary to determine in a scene where visible the number of sprocket perforations between the frame line and the margin line; and of course, the frame line in the dark film is identically located with respect to the margin line. KEWLEY'S NEW G. E. POST J. E. Kewley, hitherto General Manager of the Incandescent Lamp Department of General Electric Company at Nela Park, Cleveland, has been elected Vice-President in charge of that division. He succeeds T. W. Freeh, a pioneer in the lamp and lighting industry who since 1901 has been intimately associated with the development of the tungsten lamp. Graphite Anode Aids Tube Performance WITH the extension of the graphite anode feature, already proved in radio transmitting service, to sound equipment tubes, new standards of performance and life are anticipated, according to a statement by the Hygrade Sylvania Corp. in answer to a question as to the improvement effected by the graphite anode in tubes. "In the Sylvania 205D, for example," states the Sylvania engineering department, "there is a rugged graphite anode which makes for a sturdier tube, freer from gas and capable of dissipating more power than has heretofore been obtainable from this type. Because of the greater dissipating power, the grid inside the anode is operated at cooler temperatures, thus reducing the possibility of gas and consequent tone distortion from this element. Also, with the new construction longer insulation paths are provided, reducing the possibility of leakage between elements and consequent noises. "In this tube cobalt nickel alloy is employed for the filament, providing greater emission area and greater tensile strength when hot. The filament will not sag when the tube is mounted in a horizontal position. "The 242A tube has a thoriated tungsten filament, having been brought out to replace the old oxide-coated 211E which gave so much trouble from gas and short life. A graphite anode is incorporated, with increased heat dissipation readily noted in this type. In sound equipments where molybdenum plate tubes run with anode red hot, the graphite anode Sylvania 242A can be substituted, and while dissipating the same power, the anode will show no color whatsoever. This makes for long life and freedom from output distortion."