Movie Makers (Jun-Dec 1928)

DECEMBER 192S STUNTS for YOUR PROJECTOR Mli/itt wz ^<f IT'S all in knowing how," is the basis of many of the amusing as well as practical things which can be done with an amateur projector. With a dozen hints as a nucleus, your own ingenuity will suggest many of the interesting tricks which will increase the enjoyment of projecting. Did you ever have to show a reel in a room so small that even the maximum throw gave a very small image? Such a situation is easily remedied. Place the projector directly below the screen and project into a mirror on the opposite wall. The image is reflected to the screen and covers four times the area that it would otherwise fill, since the projection distance has been doubled and size is proportionate to the square of the distance. Thus the length of the throw is twice the length of the room and the space available has been doubly increased. Reflection of the image, however, involves the problem of inversion. It will be noticed that the mirror has the effect of turning things around and putting the left side of the picture on the right and vice versa. Correction of this inversion is effected by turning the film around in the projector. That does not mean to turn the film end for end, which would cause the image to appear up side down on the screen, but means, rather, to make a half turn in the film either in projecting or rewinding it. The quality of the image depends largely upon the surface from which By Howard E. Richardson it has been reflected. That is, a good mirror with a perfectly smooth surfact will not alter the relation of the light rays it transmits while a cheap mirror with a wavy glass will cause distortion to a degree dependent upon how bad the mirror is. Distortion can be very annoying at times but contrariwise, it can be used to burlesque a picture or to project an old film in a new way. The comic antics which a wavy medium produces by distorting faces, figures, and objects can only be duplicated at a circus sideshow in front of one of the familiar curved mirrors, or perhaps, in front of the only mirror we had to shave with on our last vacation trip and which twisted our faces around until we had to feel in order to distinguish between nose and ears. Projecting around a corner sounds hard but it's not. Again the mirror serves an important part, being placed at the corner where it bends the light rays. Not unlike the reflection of an image on a screen over the projector, the reflecting of an image around a corner will necessitate turning the film side for side in the projector to correct the tendency of the mirror to invert the picture. It is a curious fact that varying the angle at which the projected light strikes the mirror, alters neither the size nor the shape of the screen image, though of course the angle of reflection or angle at which the light is directed from the mirror must always exactly equal the angle of incidence or angle at which the light strikes the reflecting surface. Use of a mirror in projection suggests a step further — projection through a prism. Thus we come to a field which is receiving some attention by experimenters at present and which may play important parts in the movies of the future. With the projector facing the corner of the room, place a triangular glass prism directly in front of the lens and turn it slowly. When it is properly adjusted, the image in the corner will disappear and in its place, two exact duplicates will appear, one on each wall side of the corner. They will be at right angles to each other and will have a light intensity of about one half that of the original single one. The capacity of a movie house is limited to certain dimensions dependent upon the length of throw possible with modern cinematic apparatus. However, four times the present maximum may be possible if a system of prisms divides the picture equally between four screens, one on each of four walls; the projection booth located in the center thus enabling a four times increase in seating capacity. Showing a picture through a bottle of water placed before the lens produces interesting phenomena. The glass sides of the bottle must be parallel in order not to appreciably alter the focus. {Continued on page 827) FTGURE I VT id? / U V. u CO \Troy / / ~~ . Projector