The science and practice of photography; an elementary textbook on the scientific theory and a laboratory manual - Softcover
Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1918 edition. Excerpt: ...obtained from the Neue Photographische Gesellschaft, Berlin, Steglitz. As with platinotype paper, the progress of printing cannot be seen, as the image is almost invisible, and it has therefore to be followed with some kind of an exposure meter when the source of light is a variable one like sunlight. If a steady source, like a good arc lamp, be used a few trials will determine the time required. The tissue can also be bought where the gelatine layer is carried on a thin, transparent celluloid support and the printing can be done through the support, thus saving the trouble of the first transfer. The process requires more labor and skill than the ordinary developing paper process, but is not difficult enough to be beyond the reach of any ordinary worker. The method is exceedingly flexible as to the rendering of fine detail or large fuzzy effects depending on the treatment in the warm water, and as to the tone of the finished print. It can be used to advantage in lantern-slide-making for the same reasons, and has a very important ap plication in the making of pictures in their natural colors. 90. Photo-engraving.--There are many printing press methods which come naturally under this head. But the great majority of newspaper, magazine, and book illustrations are made by methods of which the half-tone zinc etching may be taken as a type. The first step is to make a negative of the subject to be copied. In this, one detail is different from the ordinary process. At a short but definite distance in front of the plate in the camera is placed a line screen made of two sets of parallel lines, the sets being at right angles to each other, and in each set the width of the opaque lines and the clear places are about equal. This breaks up the light image...
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