Moving Picture World (Sep 1916)

September 30, 1916 I NIC MOVING PICTURE WORLD 2107 '""""^Jf"" ' ' immmim»ii||m» ■gJlllU ' d > MiimliiiiMiiiilmimtiniii^ »mi[jiiMMiiiinimiiiiiMin iiiiiiiii!liniinillllllll!yj^[llllllllllininmr Projection Department Conducted by F. H. RICHARDSON (&. Manufacturer's Notice. T Is an established rale of this department that no nppnratus or other goods win be endorsed or recommended editorially until the excellence of such article! baa been demonstrated to Its editor. Important Notice. Owing to the mass of matter awaiting publication It Is Impossible to reply through the department in less than two to three weeks. In order to give prompt service, those sending four cents stamps (less than actual cost) will receive carbon copy of the department reply. by mall, without delay. Special replies by mall on matters which cannot be replied to in the department, one dollar. Both the firs and second set of questions are now ready and printed In neat booklet form, the second half being seventy-six in number. Either booklet may be had by remitting 25 cents, money or stamps, to the editor, or both for 40 cents. Cannot use Canadian stamps. Every live, progressive operator should get a copy of these questions. You may be surprised at the number you cannot answer without a lot of study. Question No. 156. What ought to be the height of the screen above floor stage, or above the main floor auditorium where there is not staget Roll of Honor on Question No. 146. The Roll of Honor on Question No. 146 consists of Joseph H. M. Smith, Fort Worth, Texas ; Wilson Hays, Barton, Md. ; W. B. Allen, Edmonton, Canada ; F. F. Bell, Palestine, Texas ; M. Nosti, Tampa, Fla. ; W. E. Bryner, Springfield, 111. ; C. E. Linstruth, Carthage, N. Y. ; Leon Pagenhardt, Westernport, Md. ; G. A. Yager, Anadarko, Okla. ; Dean A. Snyder, Bangor, Pa. ; F. N. Irvin, Lufkin, Texas ; M. Capobianco, Roseto, Pa. ; E. R. Havener, Marquette, Mich., and M. Moon, Sherman, Texas. I think the reply of Brother Hays probably covers the subject best. Reply to Question No. 146. By Wilson Hays, Barton, Md. The Questions : In your opinion is it best for the operator to handle the house lights, or should it be done from the main house switchboard, or should the operator handle a portion of the lights and the rest be handled from the main switchboard? The Answer : Lighting circuits should be so arranged that the operator can control at least one auditorium circuit, to the end that he be able to light the auditorium instantly in case anything goes seriously wrong in the operating room, such as, for instance, a fire. In some combination houses it is the custom to arrange the lighting so that the operator has to await the pleasure of the stage manager before he can control any portion of the lights. In other houses the custom Is to feed the wires from two sources of supply, these sources being a switch on the stage panel and a switch in the operating room, or on the main house switchboard. Another freak wiring system is that of controlling the lights on the inside and outside of bowl fixtures by means of a doublethrow, double-pole switch. When the switch is thrown in one direction the indirect lights are on, and when it is thrown the other way the direct lights are on. Another mistake that is sometimes made is that of controlling all the lights from one switch In the operating i oom In combination houses It Is my opinion that the operator should only control B single auditorium circuit, which will enable him to light the auditorium In case of fire or serious trouble. The rest of the Ugbtl should be controlled from the >-lage, that Is to say, In houses where vaudeville Is used every day ; If vaudeville is not used every day then tho operator should control the lights, or that part of them which are extinguished during the beginning of the performance. In straight picture houses the lighting should be so arranged that the operator may handle those lights which are to be switched on when the picture Is off, so as to brilliantly illuminate the auditorium during intermission. The rest of the circuit should be bandied from the main panel. I do not pretend to say that this is a perfect answer. As a matter of fact it is not, but it is the best one that came in. Tho subject is a big one — perhaps too big to be handled in this way. My own view of the matter is that whereas the operator should always have under his control a circuit which will light the auditorium in case of emergency, It is not best that he should handle any other house lights, partly by reason of the fact that the house lights ought to be handled by dimmers, which should be worked slowly and carefully In turning out and turning on the lights ; also switching on and switching off the lights requires the manipulation of several switches If the auditorium has any considerable size. I would like to see this matter discussed somewhat in detail in the department, because It Is one of considerable Importance and Interest. Aperture Lens. Ralph W. Martin, Los Angeles, Cal., sends in the following : In the drawing, the distance from condenser to aperture is taken at 16 Inches, which is considered a fair average that present condensers will give when working at their maximum efficiency. The width of the standard aperture is shown at AA, and the lines aa, bb, etc., are accurately drawn to show the rays as received at the aperture under the conditions given. An aperture lens of 9.23-lnch exact focus, and of plano-convex form, is chosen for the present case. It is given sufficient diameter to eliminate the use of the outer edges, and thus avoid trouble from aberrations. But aside from this precaution it does not seem probable that a lens used in this capacity, so near to the object (aperture), would give any trouble because of its inherent aberrations, so long as it is placed as close as possible to the film, and is of good material and workmanship. The precise action of the present aperture lens Is, as found by analysis, to focus the real aperture AA to a virtual image BB. The image BB is located at the position shown, and is larger than the real aperture, having a width of one inch. Now the function of the aperture lens is to further concentrate the beam of light which passes forward from It toward the objective, but it also causes the rays of this same beam to proceed as though they actually came directly from points of the image BB. Consequently in calculating the E.F. of the objective, the width of aperture must be taken as an inch instead of .9062 of an inch. It Is therefore very readily seen that for a given size of screen picture the E.F. of the objective will be a little longer than when the aperture lens is not used. ■■ HM