International projectionist (Jan 1943-Dec 1944)

in spite of their convenience. Gears must be kept to a minimum. I am aware that successful conversions have been made, but it is not to be expected that a quality of sound comparable to that of a specially designed machine should be attained. i DISCUSSION Mr. A. G. Peppy: Why should we necessarily follow the American practice of running the lamp on 110 volts? Why not a lower voltage, which would give greater efficiency? In regard to your suggestion to construct the mirror and condenser inside the envelope, while you would no doubt increase the optical efficiency, the difficulty is to produce mirrors and condensers that would stand up to the intense heat. Author: No doubt lower voltage lamps would be rather more efficient; an objection is the increased current which would need heavier leads and plugs. Existing lampholders are not good enough. I should like to see the bi-post cap adopted for all highpowered lamps. On your second point, surely a lamp was made, running on 15 volts, with a silvered bulb. I should have thought that glass that will stand up to the heat of a powerful arc could be safely used in a filament lamp. Mrs. A. E. Cotton (contributed) : A temperature of 500° C. is by no means an extreme temperature for ordinary heat-resisting condensers. Inside the bulb, of course, the condenser would be immune from draughts, which are ordinarily the chief trouble, rather than the mere temperature. Mr. F. C. Smith: In the design of 16-mm projectors, I have had more trouble with lampholders and mirrors than with all the rest of the instrument. Optically you have a much more delicate problem than with 35-mm film. Mr. Cricks referred to the accuracy of speed to which the film has to be controlled. It seems to me for this reason that portable equipment is unlikely to be really satisfactory in the future. Mr. A. I. Morgan: The problem of flicker in the discharge lamp when run on a.c. would be overcome if the film speed were • increased to 25 frames per second. Author: That is a suggestion I have previously made. I am in favor of it. Mr. P. A. G. H. Voict: The increase in speed of the picture by l/24th would not be noticed, but your music would be out of pitch. Some people have an absolute sense of pitch and are very susceptible to such changes. Mr. Townes: Development of 16-mm projectors should proceed towards the production of a machine that will run a full feature. It is possible to run a complete programme on a single reel, even with a 750-watt lamp. Author: Manv people using 16-mm machines do not take sufficient care of their machines; you may get scratches running through the whole feature. The question of gate cooling must also be overcome. Mr. Heller: A power rewind is a necessary part of a 16-mm machine. Time is important, and it should rewind at a fair speed. Author: A separate rewinder is better. Mr. Richards: A word about film damage. My experience is that the claw movement is not the prime factor, but incorrect design of gates and facilities for threading. Too much stress is put on the film damage angle. I have run sub-standard films on the Continent: I ran one film for two months, four or five times a day, without dam?se. Film shrinkage is one cause of trouble. Stock manufacturers should be able to prevent shrinkage. Trip switches are a bugbear. Author: I disagree from my experience, you cannot lay too much stress on the avoidance of film damage. In regard to> trip switches, it is certainly annoying to have the machine frequently going black, but it is better than tearing the film. Dr. Ward: I endorse Mr. Cricks's views on the need for the avoidance of film damage. A point in which I have found trouble No War Baby is the brand-new Motiograph Projector which will be available as soon as hostilities cease. For Motiograph Projectors were being made even during the SpanishAmerican war, 47 years before the scourge of Hitler. The designing of this latest equipment masterpiece was started before the paper hanger was hanging his dissenters. So when you buy your next Motiograph Projector you'll know it was created during a period of sound thinking . . . that it is not a revamped wartime product bom of a desire to cash in when theatres will be sorely in need of new equipment. It will, instead, represent so definite an advance in design, construction and operation as to constitute a virtual necessity to the modern theatre. M 0 T 1 0 G RAP HI "SINCE 1896" 4431 W. LAKE STREET • CHICAGO 24, ILL. TOMORROW'S PERFECT PROJECTION TcaUuff ORTHOSCOPE LENSES These New Lenses Will . . . 1. Definitely improve distribution of light on the screen ... No more dark edges 2> Eliminate the "hot spot" 3a Amazingly improve color projection 4a Do away with side and front seat distortion 5a Perfect background focus on longshot scenes 6a Give greater picture "depth" 1. Do away with "rainbow" effects 8a Cause film to run cooler ... no buckling ASK YOUR NATIONAL REPRESENTATIVE FOR DETAILS Distributed Exclusive// by NATIONAL SUPPLY Division of Notional * Simple * fijudwerth, InC SEPTEMBER 1944 25