Moving Picture Age (Jan-Dec 1922)

February, 1922 MOVING PICTURE AGE 17 Oft ./87 -€3f a CDs' I ^r /Jzs^wf /^s /Waii/a? /5bfa?&? ?&r/?rarf0/7S standard for slow-burning film and was known as the safety standard. This film, as well as the Pathescope, which still retains its characteristic and patented perforation, is absolutely interchangeable and can be used without adjustment or change of any kind on any narrow-width projector. Problems of the NarrowWidth Film In absolute fairness — and this department must always be conducted on the grounds of impartiality — it must be pointed out that there does not begin to be the volume and variety and choice in slow-burning safety standard or Pathescope films that there is in the professional standard. In truth, that is precisely the matter with this narrow-width film. Owing to the vast quantities of film produced for the theatres and which, with or without editing, are finally available for the various non-theatrical purposes, there are easily millions upon millions of feet of professional standard film available, and at a reasonable rental or cost for outright purchase. It has been a gigantic task and a very costly one to print the standard films onto the narrow width, and it is the rather unfavorable comparison between the available quantities of both sizes that has caused many non-theatrical exhibitors to stand by the professional size, even although it employs the celluloid base. Then there are the various diminutive films now making their appearance for limited throws and for small screens. It stands to reason that for a small screen image, say one measuring three by five feet, the professional standard or even the safety standard film is unnecessary. For the sake of economy, therefore, it becomes the part of good business to use a much narrower film. There seems to be a growing tendency to use a slow-burning film about one-half the width of the professional standard, with either one row of large perforations or with two rows of very small perforations. Undoubtedly a time must soon come when there will be a third standard film, of very small size, especially intended for home showings and for the use of the salesman and others desiring a small picture at a minimum cost for film. Many attempts have been made to substitute paper ribbons for transparent film, the paper ribbons serving to reflect their images through an optical system and onto a small screen. Likewise, attempts have been made to use glass plates, with parallel row's of ■ images, in place of film. The glass or slow-burning disk, with images arranged in spiral form, is another idea which persists -and which may have possibilities for home entertainment. But in the long run there is no real substitute for the transparent film, no matter what be the expense involved. Sfartdan/ F/Y/n -/37S—/./091 «J33 soe' w w jb £3 l-j/o-4 .073 study, and no operator can afford to stint in this particular. Too often, so it seems, the screen receives scant consideration, since most operators take it for granted that any white surface is good enough. X -1. 102 F&favrfb/fs some on 6 aft s/e/es THE SCREEN: A WORTHWHILE STUDY THE PROJECTOR ' is no better than its screen. It may be the finest projector in the world, but if it is being used in conjunction with a poor screen the results are certain to be unsatisfactory. Hence the screen is a matter worthv of careful The Improvised Screen The most elementary form of screen, of course, is a plain white wall or ceiling. Such an improvised screen may serve for a portable projector, but it can hardly be taken seriously for a permanent, established nontheatrical exhibition of any kind. If economy is a cardinal consideration, then resort may be had to this simple formula : Mix boiling water and whiting until the mixture is of a creamy consistency. To one gallon of this mixture add one pint of fluid glue and one pint of glycerine. Paint on the stretched canvas with a wide brush and lay it .on smoothly. When dry, the canvas can be rolled if desired. The same preparation may be used for painting a screen on a wall, where the installation is a permanent one. Aluminum paint can also be employed as a screen. It is of interest to note that the eye sees a picture on the screen not by the light which strikes the screen, but by the light which the screen reflects to the eye. If we imagine a perfectly black screen, one which reflects absolutely no light, it is at once evident that no matter how much light we project on that screen we shall receive absolutely no reflected light. The Reflection Factor Thus it comes about that screens used in regular practice vary in reflection factor — that is, in their power to reflect light — through very wide limits ; hence it is obviously necessary to consider the reflection factor of different screens when discussing screen intensities. Neither is it correct to assume that the screen which reflects the highest percentage of light striking it is necessarily the best screen to use, for the manner in which the reflected light is distributed is also a factor which affects the brightness of the picture. For example, it is possible to conceive of a screen which reflects a very large proportion of the light striking it, yet which, due to the fact that it distributes the reflected light far out to the sides, is actually less satisfactory than one which reflects a lower percentage of the light striking it but which confines its reflected light within useful angles. From the standpoint of their reflection characteristics, screens in common use may be divided into two classes : diffuse-reflecting screens and spread-reflecting screens. Of the first class, white-cloth screens and plaster screens are typical. A whitecloth screen when clean may be made to reflect as high as 70-75 per cent of the light that strikes it, and a plaster screen 80-88 per cent (according to Mr. R. P. Burrows of the Society of Motion Picture Engineers, to whom the writer is indebted for these data). Please note, however, that the light is feflected at wide angles. Such (Contin'd on page 29) 7°aMescd/oe 7///?? Fro/ffe Ow o/secfs corner/xyerafo/is