Moving Picture Age (Jan-Dec 1922)

March. 1922 MOVING PICTURE AGE 19 EquW. focus Inches 15 ft. 20 ft. 25 ft. 30 It. 35 ft. 40 ft. 45 ft. 50 ft. 60 ft. 10 ft. 80 ft. 90 ft._ 100 ft. S 8.0 10.8 13.S 16.3 19.0 , 8.3 11.6 14.8 17.8 20.6 5X 7.3 9.8 12.3 14.8 17.3 19.8 7.9 10.7 13.4 16.1 18.8 21.6 8 6.6 8.9 11.2 13.5 15.8 18.1 20.4 7.3 9.8 12.3 14.8 17.3 19.8 22.: IjJ 6.1 8.2 10.4 12.5 14.6 18.7 18.E 67 9.0 11.3 13.6 15.9 18.2 20.S 7 5.7 7.6 9.6 11.6 13.5 15.5 17.5 19.4 6.2 8.3 10.5 12.6 14.8 16.9 19.0 21.2 Vi 5.3 7.1 8.9 10.8 12.6 14.4 16.3 18.1 5.8 7.8 9.8 11.8 13.8 15.8 17.8 198 8 6.6 8.4 10.1 11.8 13.5 15.2 170 20.4 7.3 9.1 11.0 12.9 14.8 16.6 18.5 22 3 VA 6.2 7.9 9.5 11.1 12.7 14.3 18 0 182 6.6 8.6 10.3 12.1 13.9 15.6 17.4 20.9 1 5.9 7.4 8.9 10.5 12.0 13.5 15.1 18.1 21.1 6.4 8.1 9.8 11.4 13.1 14.8 164 19.8 23.1 «K 5.6 7.0 8.5 9.9 11.4 12.8 14.2 17.1 20.0 6.1 7.8 9.2 10.8 12.4 14.0 15.5 18.7 21.9 10 5.3 66 8.0 9.4 10.6 12.2 13.5 16.3 19.0 21.8 5.8 7.3 8.8 10.3 11.8 13.3 14.8 17.8 20.8 23.8 12 5.5 6.6 7.8 8.9 10.1 11.2 13.5 15.8 18.1 20.4 6.0 7.3 8.5 9.8 11.0 12.3 14.8 17.3 19.8 22.3 14 5.6 8.6 7.6 8.6 9.6 11.6 13.5 15.5 175 19.4 r.2 7.3 8.3 9.4 10.5 12.6 148 16.9 19.0 21.2 11 5.8 8.6 7.5 84 10.1 11.6 13.5 15.2 17.0 6.3, 7.3 82 91 11.0 129 14.6 166 18.5 11 5.1 5.9 66 7.4 6.9 10.5 12.0 135 15.1 5.6 6.4 7.3 8.1 9.8 11.4 13.1 14.6 16.4 20 5.3 60 66 8.0 9.4 10.8 12.2 13.5 5.8 6.5 73 8.8 10.3 11.8 13.3 14.8 22 54 60 7.3 8.5 9.6 11.0 12.3 59 66 7.9 9.3 10.7 12.0 13.4 » 5.5 6.6 7.8 8.9 101 11.2' I 60 " 8.5 9.8 11.0 12.3 Table Showing Size of Screen Image When Lantern Slides Are Projected. Size of Mat Opening, 2% by 3 Inches films, motionpicture engineers found it necessary to establish a new size known as the safety standard. This size measures 28 m i 1 1 i m e t e r s in width instead of the 35-millimeter width of the standard film; furthermore, it has 20 images to the running foot instead of the standard 16. The introduction of this narrowwidth film has given rise to the fourth type of projector, which differs quite materially from the three preceding types. Having eliminated the fire hazard at the very source, namely, the film, it follows that machines making use of such films can do away with the fireproof magazines, fire shutter, and other devices so necessary when inflammable film is being handled. So the safety-standard projectors are distinguished by their utmost simplicity and compactness, and are ideal for portable purposes. Practically all the offerings along this line are motor-driven, and can be operated by anyone with but a few minutes' instruction. Such ' machines are available for screen images up to 5 by 8 feet, and the author has employed a well-known make in church-entertainment work with as many as 250 persons in attendance at one time. In considering this class of projector, it is well to give some thought to the films available. While there are libraries in operation which supply safety-standard film on a regular subscription basis or on a daily rental basis, there can be no denying the fact that the list of available safety-standard reels is very small compared with that of standard films. And since a projector is of little use without a continual supply of new film subjects, the matter of available film is an important one. It is not for the author to decide how the existing safety-standard subjects compare with the standard film subjects; these facts are placed before the reader for his guidance only, and he must decide for himself. Let the reader write to the makers of safety-standard projectors for a list of libraries or exchanges, and for a list of their offerings, as a preliminary to buying a machine of this type. If the reader is satisfied that the offerings are sufficient for his needs, all well and good. He is the final judge. Many schools, churches, clubs, and even homes are using the safety-standard type, for the reason that it is absolutely safe. It is approved for use anywhere and everywhere, without licensed operator or booth or other formality. Its users are well satisfied with the film offerings, and it is certain that the list of safety-stan d a r d films is being steadily increased. Lastly, we come to the non-standard type, which comprises a large number of machines of extra small size, making use of slowburning films that are half the width of the professional standard. Such machines are intended primarily for the home, where expense is a prime consideration. Obv i o u s 1 y , in the school or church or club the cost of Cross-sect, onal View of incandescent Lamphouse fi< „„t_i „_„ ua Used in a Typical Semi-Professional Projector, "\ul .JCIUdl (-d" ue Showing the Simplicity of Such an lllumlnant distributed among tqulv. locus 15 20 25 30 35 40 45 1 SO 60 70 | 80 90 100 Inches ft. ft. ft. ft. ft. ft. It. ft. ft. ft. ft. tt. ft. VA 4.3 64 6.0 9.6 11.3 12.9 14.5 16.1 6.5 8.7 11.0 13.2 15.4 17.6 19.8 22.0 VA 5.4 6.8 8.2 9.6 10.9 12.3 13.7 16.4 7.4 9.3 11.2 13.1 14.9 16.8 18.7 22.4 3 4.5 5.7 6.8 8.0 9.1 10.3 11.4 13.7 16.0 6.2 7.7 9.3 109 12.4 14.0 15.8 16.7 21.8 VA 4.9 5.8 6.8 7.8 8.8 9.8 11.7 13.7 15.7 6.6 8.0 9.3 10.6 12.0 13.3 16.0 18.7 21.4 4.2 5.1 6.0 6.6 7.7 8.5 10.3 12.0 13.7 15.4 5.8 7.0 8.1 9.3 10.5 11.6 14.0 16.3 18.7 21.0 4K 4.5 5.3 62 6.8 7.7 9.1 106 12.2 13.7 15.4 6.2 7.2 8.4 9.3 10.5 12.4 14.5 16.6 18.7 21.0 48 5.4 6.1 6.8 8.2 96 10.9 12.3 13.7 6.5 7.4 8.4 9.3 11.2 13.0 14.9 16.8 18.7 i'A 4.3 4.9 5.6 6.2 74 8.7 9.9 11.2 12.4 5.9 e.7 7.6 8.4 10.2 11.9 13.6 15.3 17.0 4.5 5.1 5.7 6.8 8.0 9.1 10.3 11.4 e.2 7.0 7.7 9.3 10.9 12.4 14.0 15.8 6i< 4.7 5.2 6.3 7.3 8.4 9.6 10.6 6.4 7.1 8.6 10.0 11.4 13.0 14.5 4.4 4.9 5.8 6.8 7.8 8.6 9.8 VA 6.0 6.6 4.5 6.2 8.0 5.4 7.4 9.3 6.4 8.1 10.6 7.3 10.0 12.0 82 11.2 13.3 9.1 12.3 8 5.1 7.0 6.0 8.1 68 9.3 10.! 8.5 118 so many persons that it becomes a small matter, whereas in the home the cost must be borne by a very small number of persons, and therefore becomes considerable, if not in most cases prohibitive. Hence of late years many attempts have been made to introduce small-sized slow-burning films which could be made and rented at such a low cost as to make motion pictures possible in most homes. In this class of projectors we find all kinds of machines, ranging from a miniature of the safetystandard type to a novel machine using disks with the images arranged in spiral form. Obviously, due to the small size of the images, the projectors in this class can only be used in connection with a small screen, and the mechanism, being inexpensively constructed, does not make for the best kind of projection. Aside from home use, projectors of this kind may find a limited application for salesmen, although the safety-standard and portable projectors are so much better that it is the part of false economy to use the smaller films. So, having laid out the entire field of projection in five classes, the road is paved for a consideration of various projectors in the different classes of types, in our subsequent issues. ;; Table Showing Size of Screen Image When MovingPicture Films Are Projected. Size of Mat Opening, 11/16 by lb/16 Inch PROJECTION TABLES SINCE optics plays a leading role in projection, there is always need for a set of projection tables that will enable any operator to determine the performance of any given projection lens and to figure on any given screen image. So we present the two accompanying projection tables, one covering the size of screen image when lantern slides are projected, and the other the screen image when moving pictures are projected. These tables, it will be noted, are based on three factors: (l)1 the equivalent focus of the lens in inches; (2) the distance between the lens and the screen; (3) the dimensions of the screen image. Thus if one has a 5}^-inch focus lens, at a distance of 35 feet the screen image will be 4.3 by 5.9 feet ; at 40 feet, 4.9 by 6.7 feet ; at 45 feet, 5.6 by 7.6 feet, and so on, when p r o j e cting motion p i ct u r e s . It must be at once obvious that such a table can be used for deciding how far back a p r o j e c tor must be placed to fill a certain screen with a given lens ; or, if a definite location has been decided upon for the projector, and the screen size is fixed, one can determine what focal length lens should be used. The table g. 1 and 2 the radiant, 1. e., the crater, needs to be properly adjusted laterally, it is too far to the right or left. Id fig. 3 and 4 it is too high or too low. In fig. 5, 6 and 7 it is too near or too far from the condenser. Fig. 8 shows it to be* in correct position, the field being entirely cleai. Adjustment of Light Successful results in projection depend largely upon the correct adjustment of the lamp, which must throw a brilliantly illuminated circle upon the screen. After the objective is focused, as will be evidenced by a sharp clear image on the screen, remove slide and slide holder, and examine the illuminated circle. If the light-is centered and the lamp correctly adjusted this circle will be clear and, entirely free from coloration or shadows. The diagrams above illustrate the results of defective centering.showing the shadows and stating the causes. These can be speedily remedied and a little practice will soon make one adept in centering the light accurately.