COLOR PHOTOGRAPHY

is the method of reproducing a photographic image in natural colors. No satisfactory method has as yet been devised for making a permanent reproduction on paper or other fabric by photography alone, although several methods are available for making colored transparencies, lantern slides and motion pictures, The most interesting of these is the following proce , perfected by M. Lumbiere, The plate consists of two coatings. The one is a color screen, consisting of a homogeneous mixture of orange, green and violet dyed starch grains, so proportioned that the mixture appears colorle . It is varnished for protection. The second coating is the usual panchromatic light sensitive film. In making the exposure the lens must be fitted with a color filter adapted to the particular light used. The plate is so placed that the starch grain color screen faces the lens; thus the light rays pa through it before reaching the photographic film. The latter is developed in the usual way, and the image reversed by chemical and light treatment so as to form a positive. This is the transparency or lantern slide. The dyed starch grains have remained unchanged during the proce and they supply its natural colors to the image. When making colored motion pictures, the film (which is a panchromatic one, and sensitive to all colors), is exposed in a special camera, fitted with a three section light filter in front of the lens. This is so geared to the shutter of the camera that an exposure is made through sections of the screen. These sections permit red, green, and violet rays to pa succe ively, so that one exposure records only the reds, the second the greens, and the third the violets; then the cycle starts again with the reds. The record on the film is not in color, but is in a scale of greys. The film is developed and a positive prepared in the usual way. For projection a revolying three-part color screen is again used, which must be so synchronized with the film, that the proper picture is projected through the correct screen. The pictures, as flashed on the screen, consist of a red, followed by a green and a violet. The film however, is run. about three times as fast as the ordinary black and white, and consequently the eye does not have time to register an image of the various simple colors, but sees only the composite which appears to be in natural colors. There are several other methods of producing color transparencies. That by optical interference attains its effect in much the same way as the hues of soap bubbles, oil films, and mother of pearl are produced. In the three—color proce , perfected by Frederick C. Ives,.three negatives are made through respectively, red, yellow and _ blue screens. They are then developed and placed in an apparatus, which simultaneously illuminates them by rays of the same color as was the screen through which they were made, and superimposes their images by reflectors. The resulting combined image reproduces the subject in its natural colors.