Moving Picture World (Nov-Dec 1922)

782 MOVING PICTURE WORLD December 23, 1922 will have small sympathy if you get soaked by the exchange. Examine General Instruction No. 9, page 603 of your new handbook — I assume that you already have your copy. If not, why not? — and set your tension as it should be. A too heavy tension greatly aggravates emulsion deposit, as you can readily understand. DON’T imagine that the tension is set right when the new projector comes. If it is it is purely by accident. The projector manufacturer does not and cannot know under w'hat conditions any given projector will operate — whether it will fall into the hands of a “speed demon’’ or not, so he must perforce set the tension for the WORST POSSIBLE CONDITION, which means a tension set for at least 125 feet of film per minute. You may never exceed seventy feet, and it requires small reasoning power to see that the tension of the new projector will, in that event, be too heavy for your work. If you have a projector without a tension adjustment j’ou are out of luck, as you will be compelled to lighten the tension by bending the springs — a slow and difficult task, but one which can and must be done. If you have a projector with a tension adjustment, then follow the instructions laid down in general instruction No. 9, page 603 of the new handbook, and all will be well. But what I want to know is, what is the view of other projectionists as to the duty of the exchange in the matter of film lubrication? Also I will say that the Eastman Company will soon place on the market a machine which looks as though it will solve the first run film lubrication problem. From Spain Jose Sola Guardiola, Barcelona, Spain, writes : We are constructing one of the largest cinemas of Europe. Knowing your great experience in such matters, we would be obliged to you for advice on the screen. What we want to know is what cla.ss of screen you consider best of all and size of same. Room is thirty-three meters in length, thirty-one meters large (presumably meaning wide) and twenty meters high. Distance of projection is thirty-five meters. It is difficult to give advice on such matters as screen size when one knows little or nothing about the customs of the country. Australia, for instance, for the most part uses a picture so large that to my way of thinking it is distinctly bad practice, yet it would be useless to adyise a small picture because Australia exhibitors firmly believe a huge picture is necessary. An 18 or at most 20 foot picture is ample large for any theatre. Your room is, roughly, about 110 feet front to back, 102 feet wide and 65 feet high. On the plan you drew the projection distance is approximately 120 feet, or 35 meters. Problems There are problems connected with the matter which prevent me from giving intelligent advice without further knowledge. If your screen is within say twenty feet (six or seven meters) of the front row of seats you must either use a screen having excellent diffusing powers or have a tremendous “fadeaway.” By this I mean that if a screen of low diffusing power be used, while the picture may be brilliant from in front of the screen, at the extreme side front seats it will be very dim; also you will have a tremendous distortion from the extreme side front seats. Everything on the screen, as seen from those seats, will be very thin and tall. What I would strongly advise you to do is to send six dollars at once, and have a copy of the new handbook sent you. The matter dealing with the screen, pages 219 to 267, is precisely what you want. To give you any kind of comprehensive understanding of the matter in this department or by letter would require at least thirty pages of manuscript, with a half dozen tables and an equal number of drawings. Much as I would like to help you it is impossible to spare either the time or space. The handbook is what you need. It is all there, and in excellent form, with tables and data enabling you to apply the knowledge to your own house. It Travels David Livingstone, projectionist, Tioga Theatre, Owego, New York, is having trouble which he describes as follows: Our current is 110 volts A.C. We use a Hallberg Economizer at fifty amperes. The economizer feeds both lamps, so that striking one arc kills the other. In the second edition of your handbook you recommended a carbon set, which we are using. The carbons are % cored. The trouble is that the flame travels around the outer edge of the carbon. Usually the light then strikes directly toward the back of the lamphouse. Sometimes It will light half the picture. We can find but one remedy, viz: to keep the carbons separated about % of an inch, but this gives a blue field below and a yellow above. I would be glad to have you call at the Tioga if ever you again pass through our city. A Bit Rusty There is so comparatively little A. C. used at the arc now-a-days that I am a bit rusty on such troubles. I think, however, that your difficulty is most likely due to damp carbons. Suppose you park about a dozen of them on the top of your lamphouse, or on its floor, if there is room, and leave them there for three or four days. Then try them and I think you will find the arc will stay put. If not, then advise me and I’ll refer the matter to the carbon manufacturers and see what they can get out of it. The second edition? Man alive! I did not suppose there was still one of them still doing service. Take my advice and invest six dollars in one of the new books IMMEDIATELY. The second edition has been out of date for five long years. You must invest a little money in knowledge if you want ever to get ahead. Six dollars may seem quite a lot to you, but what you get you will find to be worth several times that sum. Oh ! yes, by the way, be sure you haven’t a lot of lamp lead (wire) inside the lamphouse, laying in a coil. This has been known to set up magnetic action and disturb the arc. Don’t think that is your difficulty, but look into it anyhow. I will be glad to give you a call if I ever pass through Owego again. An Argument Two projectionists of Boston, Hub of the Universe, set forth the following: Brother Umtl Ump and myself (names requested to be kept a dark, dense mystery) have had an argument and have agreed to leave it to you, with a bet of a dinner for ourselves and squaws on the result. The burning question is: Would it be practical to use fifty amperes D.C. at one arc and 100 amperes A.C. at the other without the audience seeing a difference at change-over? In this we assume that both arcs be handled in the best possible manner. One of us says it could be and the other says it could not. Which is right? I think what the yesser has in mind is merely screen illumination. If this were all maybe the no man thought further — maybe not — then it might be possible that there would not be sufficient difference to cause the audience to notice when change-overs were made. But screen brilliancy is NOT all. There is the quality of the light to take into consideration, and there is a great difference in light quality from an A. C. arc and a D. C. arc, especially if the A. C. carbons be used. The light from an A. C. arc is very much more harsh. It contains what is, I suppose, more of the violet rays. It is also more penetrating. D. C. light is “smoother” and more soft and pleasing. That is not very well put, but the terms “smoother” and “soft” are the best I can think of to convey the idea. The man who voted no is correct, and the yesser will kindly step up to the window of the cashier when the dinner is finished, but inasmuch as probably you may both have had merely the item of screen brilliancy — density of illumination — in mind, I would suggest that the squaws do NOT order too expensively and that the hemales stick to refreshments of reasonable price. Flicker Elimination L. S. Cusick, projectionist. Peck’s Theatre, LaSalle, Illinois, says: I have two Powers projectors and am using sixty cycle current. Have a projection distance of about 75 or 80 feet. P.'otating shutters are set to eliminate all travel ghost. Question; What shall I do to eliminate flicker when projecting at ANY speed? Your question is not very clear. You may mean what can I do that will enable me to project at any desired rate of speed, no matter how fast or slow, without flicker, in which case there is no answer, for the simple reason that it cannot possibly be done. Presuming that you already have your Fourth Edition Handbook, turn to page 611 and study General Instruction No. 22, which continues to page 625. When you have mastered what is therein contained you will not ask such a question, because you will understand what flicker is, why it is and how far you can go in its elimination. To set it all forth here would consume several pages. You also may mean that you now have a flicker, no matter at what speed you project. If this is true then it is likely that you are using a rather “brilliant” screen, and using the maximum of current very efficiently. It is also quite certain that you never project very much in excess of sixty feet a minute. Give All the Facts Kindly give me all facts and I will see what can be done for you. By all facts I mean, what kind of screen do you use? How many amperes at the arc? Do you use rheostats or transformers, and if the latter, what kind? What is focal length of condenser lenses? Are they piano convex? How far are they spaced apart? What is distance front surface of converging lens to film? What distance film to first lens of projection lens? What is free diameter of projection lens and what is size (width) of picture? What is your maximum speed of projection? Any other information which you may think will help me in forming a opinion of your case. Handbook Error Under table No. 18, page 393 of the handbook, the printer man got the line of caption all balled up, and it was not noticed in proof reading, it seems. Below the line appears as it should be. Owners of the handbook should clip this out and paste it over the one on the book. This is the line: 1 Sq. mm is .00155 of a Sq. inch. 1 Sq. inch equals 645.2 Sq. mm. As I said, just clip the line above out and paste it in the book over the caption line under table 18, page 393.