Motion picture projection; an elementary text-book (1921)

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MOTION PICTURE PROJECTION 129 show and loss of business. Now, a poor lens not only will not focus sharply but the image is flattened and lacks contrast because what should be black becomes gray and light and shade gradations of the film image are not reproduced in their proper values. Gundlach Projection Lenses on the contrary give uniformly sharp definition with the utmost illumination and the picture is brilliant because all the contrast of the film is preserved while the shadows show more detail due to the additional light obtained by their large working aperture. The Screen Picture The size of the film image is 24x1" and the opening in the aperture plate has been standardized by the principal machine manufactures at our suggestion and is now 29/32" wide with the height *A of the width. The picture is magnified in the same proportions, therefore, the screen must be 9 inches high for each foot in width. For example, 9'xl2', 10'6"xl4" or 12'xl6'. A picture 16 ft. wide requires a magnification of the film image of about 212 diameters or nearly 44,944 times the size of the original. The importance of standardization of the opening in the aperture plate may be realized from the fact that the two sizes formerly used 15/16!' wide and 29/32" wide with a difference of only 1/32" would result in a difference of about 6 inches between the width of pictures made with matched lenses for a picture 16 ft. wide so that pictures of the same size could be obtained only by using lenses of different focal lengths, an inconvenient and difficult method of securing this result.