Moving Picture World (Jan - Feb 1919)

January 4, 1919 THE MOVING PICTURE WORLD 83 netrs is the governing body in matters i.t this sort. What it says "goes," though it is to be expected that considerable time will be required to eliminate a word which, however inappropriate, has become so thoroughly established by usage. And now, gentlemen, it is up to you to "live up to the word." A high-class man in Cleveland remarked, when he heard of the action: "Gee, Richardson, its a crime to apply the term projectionists to some men now in the game." True, it is, but that is just the point, or one of them. If you mentally admit you are not deserving of the name, it is up to you to make yourself worthy of it. Projectionist means something. The title is now officially yours; are you worthy of it? Size of Screen and Drop Screen. From a Western town comes the following: "Attached find drawing of elevation of interior of my new moving picture theatre. Will you advise as to what size screen I should use? Want one screen on back wall, which will give an 89 foot throw, with front row of seats 28 feet 6 inches from screen. What size screen can I use? Want a second drop screen at front, as indicated in drawing. This screen will be for use when we have traveling shows or vaudeville. Throw to front screen would be 70 feet and front row of seats would be 10 feet from it. What size screen should I use for the front?" You will observe I have drawn in the light ray, the tilt of back screen and have extended the level of stage floor out over the auditorium floor in a broken dotted line; also have indicated location of front row of seats. The scale of your drawing seems to be & inch to the foot. You will run into some difficulty regarding your front rows of seats. For that length of house you really should have a 12-foot picture, but that would be ten feet high, and, as you may readily ascertain, the eyes of a small adult will be not more than 3 feet 6 inches from the floor when seated in an ordinary theatre chair, while those of a child will be considerable below that level. Now, as shown by my lines, with a 10-foot high picture it will be just about 3 feet 6 inches from floor line to line drawn from bottom of picture to point directly over front row of seats, hence the child patron cannot see bottom of picture from front row of seats; also probably a small woman would not have quite full view. If you cut down to an 8xl0-foot picture, raising it as far as possible, you will "get by" on the foregoing, but will have too small a picture on your front screen, the size of which is automatically fixed by the size of the picture on the back screen, unless you want to have two projection lenses and change them every time you change screens. On the whole, I would suggest a 10x12 picture at rear, which will give you almost exactly an 8x10 in front. The question is, however, whether you can focus on both screens with one lens. I doubt it, unless you have a special arrangment in the form of a telescopic lens holder made. You see the lens will have to be considerably further away from the film to focus at 70 feet than at 89 feet. Your lens diameter might not be right for both propositions, but that will not be bad, because the front screen most likely will not be used much anyhow. On the whole my advice is a 10x12 picture on rear screen, using 40 amperes D. C. or 60 A. C, and following lens combination, etc.: 40 D. C, use two 6% condenser lenses so set that their curved surface apexes are not to exceed 1/16 inch apart, with 18Yz inches from centre of condenser combination to film; projection lens diameter, 2 inches — its opening, I mean, of course. Revolving shutter must be placed according to back focus of lens, and wont be right for both screens. See table published in December 28 issue for correct shutter position, setting it for back focus of lens when rear screen is ifi use. Having lined up for back screen, drop front one, focus on it and black its edges up to picture, making border of black two feet wide. Outside this have front screen decorated in dark colors. Note, if you find you cannot focus on both screens have your local machine shop make a telescopic lens holder allowing you to move the lens further ahead for front screen. Under present conditions all advice is qualified by the fact that you may not be able to secure projection lens of focal length to give exact size picture advised. But in this case don't exceed 10x12 for rear screen unless you want trouble from occupants of front seats. Front picture should in no event exceed 10 feet in width. The lens combination for 60 amperes A. C. and 40 amperes D. C. is the same. Baird Company Purchases Edison Machines and Parts. An inquiry directed to the Edison Company by this department, asking what, if any arrangements had been made for users of Edison projectors to get repair parts, brought the following: "Replying to your inquiry will say that we have disposed of the stock of projectors and parts for old models of Edison projectors, as well as for the Super Kinetoscopes, to the C. R. Baird Company, 24 East 23d street, New York City. It is the intention of the purchaser to supply repair parts for Edison projectors now in use. I shall be glad to supply any further information you may require; also to answer any inquiries you may receive regarding Edison projectors. Signed, Thomas A. Edison, Incorporated, Per J. W. Farrell, Motion Picture Division." And thus, presumably, endeth the tale of the Edison projection machine. First on the market, it could have succeeded largely, had the company kept abreast with progress in the matter of improvement as the years rolled past. But the policy of the Edison company, as applied to its projector, was to put out a model and make no change therein until it was hopelessly out of date. With the enormous prestige of Mr. Edison's name, had the company put the same energy into improvement and keeping its projecter right up to date that its competitors did, I venture the assertion it would today have not only been by long' odds the leading projector in the American market, but would have made successful competition a very difficult matter indeed. "But instead of so doing, in all the years that passed, until linally the Super was placed on the market, the general form of the mechanism was altered but comparatively little, and the improvements therein were, by comparison, absurdly few. From one to 2-pin, from wooden to metal frame and from inside to outside shutter pretty well tells the tale. Personally we are sorry the Edison Super was not pushed to success, for we firmly believe it was, barring some faults which could have been overcome, a most excellent machine. We are of the opinion It would have been made a big winner. But as we understand the matter, it is a dead issue, and the Edison company has passed definitely out of the projection machine manufacturing field. I Just Simply Can't See It. Doctor Kellner, Bosch & Lomb Company, for whose scientific knowledge of lenses and light I have very high regard, makes one statement which I am unable to make line up with what little I know of the optics of the projector. He says the spread of the light ray back of the aperture is due entirely to spherical aberration in the condenser. Maybe I'll simply make a monkey of myself, but all the same I'm going to say I cannot, and do not, believe that statement. Having thus committed myself and laid myself wide open to attack by the good doctor, I'm going to set forth my reasons for daring to dispute so really eminent an authority. First, let us assume a perfectly corrected condenser and the crater in exact focus at the film, a glance at figure I will, it seems to me, prove, absolutely, that the ray beyond aperature C will and must diverge; also that divergence will and must be in proportion to the distance of the condenser from the aperture. It is true, however, that under this condition the divergence would not be a very serious matter, insofar as light loss be concerned. But with a corrected condenser having the crater in focus at the" film would be even less possible than now and it is entirely impractical now. Under actual operation it is claimed by practical men, who had made exhaustive study of the projector optical system, and who have accomplished much in the way of real, tangible benefit to the projectionist in the way of assisting him to work improvement in his projector optical system, that it would be imposible to get satisfactory results with a corected condenser, and that spherical aberration in the condenser serves a useful and a very necessary purpose in producing evenness of illumination on the screen. With this latter argument I am unable to either agree or disagree, never having had the opportunity to try it out in practice; also to date a corrected condenser is an impractical proposition, because of its cost and the lack of any feasible method of preventing at least oc Outlme Sector) 5«lv j4 In l«