Motion Picture News (Sept-Oct 1918)

p t c nib c r 2$ , i g i S (Equipment Service) 2067 « in the light cone projected to the screen, hence the screen lens are given by: B X p X c L = — v — • ere the various terms have the meanings previously assigned. Xote — In each of the preceding expressions the same units of ith, area and intensity should be used in the terms representing se respective quantities). t remains to point out that the screen intensities found from above expressions only hold good for perpendicular incidence the light, i.e., at the center of the screen, because a well known tells us that in the case of oblique incidence of the light rays illumination falls off in proportion to the fourth power of the ine of the angle of incidence which the rays make with the mal to the screen ; that is : 1 = 1 cos* <t>, ;re <P is the angle of incidence with respect to the normal, hus it is seen that the illumination at tbe edges of the projected ure is not so intense as at the center, and the falling off, i.e.. values of I cos' <t> for the various angles of incidence have been ulated (see Camera Department of News, December 29, 1917. e 4607). As, however, the angular extent of the projected ure is usually very moderate, being seldom in excess of» 10 rees (at which figure the marginal intensity is 00 per cent of t in the center) the loss due to obliquity of incidence can be lected, except in the case of relatively short focus objectives, en the intensity at the margins of the image is noticeably less n that at the center. l further cause of decreased intensity at the margins of the •jected picture arises in the fact that the extreme edges are served by the entire effective aperture of the objective, but ? vignetting action is also so slight in most cases as to be left of consideration, and may be further decreased by the use modern types of projection objectives, and by proper adjustnt of the projector optical system. ed Cross Institute Has School of Motion Picture Operating for Cripples '7E have always taken the stand that motion picture operating » is a regular trade, or profession, and as such can only be jperly learned by actual apprenticeship, whereby its require•nts and details are learned under actual operating conditions, d at the expenditure of sufficient time on the part of the student insure his gaining complete mastery of both the theoretical and ■ practical phases of the work. Xaturally, in view of this attitude, we have never looked with \or upon the schools of motion picture operating which have me into existence from time to time, because in the past no 100I of motion picture projection has offered a course of inuction which would be comparable to the experience gained by prenticeship in a theatre, and because, furthermore, the various iools have been solely started with a view to trading upon the sceptibilities of many people who entertain the idea that posi•ns in all branches of the motion picture industry are highly munerative. The sole aim of these various schools of motion picture operatj, therefore, has been to teach their pupils how to pass the inicipal operators' license examination, rather than how to skillUy and properly project motion pictures, for which latter the" hools have neither adequate equipment nor competent instructors. Although we have in the past been obliged to condemn these •erator schools on countless occasions, this course has not been ompted by a narrow viewpoint in the matter, and we are pleased set forth in the following our impressions of a school of Dtion picture operating recently visited by us, which does not long in the category with the ordinary' schools. This is the school, or class, in motion picture operating, inauguted about two months ago, and maintained by the Red Cross stitute at 331 Fourth avenue, New York City, where cripples are ved from lives of idleness by teaching them useful trades — us making them independent and self-respecting members of e community. This worthy work of rehabilitating crippled youths and men was idertaken experimentally by the Red Cross Institute with the view assisting the large number of soldiers who will undoubtedly turn from Europe in a more or less disabled condition, and hile the influx of war cripples has not as yet become noticeably large, the Institute is giving tliejr plan a thorough tryout by maintaining classes composed of crippled civilians, who are taught printing, mechanical drafting, oxy-acetylene welding, the manufacture of artificial limbs, jewelry making and motion picture operating. The practical instruction in these various trades is carried out on an extensive scale in rooms, or shops, well equipped with modern machinery, and a trip through the Institute will prove an eye-opener to the average able-bodied civilian. As, however, the work of the Institute is fully described in its various booklets and is receiving notice in the public prints, we will proceed to describe the section in which we are here primarily interested — the class in motion picture operating. A Corr.er of Projection Class-Room Red Cross Institute The class is instructed by James R. Cameron, who combines extensive experience with the patience so necessary in successful teaching, and the class-room is on the third floor of the Institute building. A corner of the room is shown in the illustration, from which it will be noted that there is an extensive array of the necessary operating equipment. This is being rapidly added to, through the kindness of the equipment dealers and film producers, and includes amongst other items : complete Power and Simplex projectors, Acme portable projector, Hallberg economizer. Powers inductor, Hallberg motor-generator, Hallberg four-in-one regulator, a complete distribution board (shown in the photo) fitted with voltmeters, ammeters, and a variety of wiring systems. To the extreme right in the photo will be noticed a corner of the asbestos booth installed in the class room, which is completely equipped with operating appliances. The Simplex projector is installed in this booth, and as the class room looks out on a large assembly hall below, a good sized picture may be projected across this room to the opposite wall. Since the accompanying photo was taken Mr. Cameron has added many puzzling connections and complicated circuits to the distributing switchboard, which must all be unravelled by his pupils in the course of their tuition, while they are frequently called upon to go over a circuit from the cellar up, to locate a short-circuit " planted " by the instructor. Electricity does not form the major portion of the instruction given by Mr. Cameron, who has endeavored to present a well rounded course, giving due consideration to the optical and mechanical phases of projection as well, and including the necessary safety precautions which an operator must always bear in mind. It will be contended by many, and perhaps with some justification, that the operating-room of a theatre is not a place to be entrusted to the charge of a cripple. We have known' instances where a one-armed man has made good as a projectionist, and not a few instances have been heard of where leg-cripples presided over the projection in theatres. An arm-cripple is manifestly at a disadvantage when attempting to project motion pictures, but it appears that a leg-cripple whose powers of locomotion are not seriously impaired, or who is provided with artificial limbs, should be capable of assuming the work of an operator, and it is this sort of disabled men who are taught motion picture projection at the Red Cross Institute. i A