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Double-Coated Stock 645
Optical printing is no new idea, as it has been employed from the very earliest days of photography, as in the making of lantern slides and enlargements. One has but to turn to Sutton & Dawson's "Dictionary of Photography," page 279, to find the following passage : "Printing Process. By 'Printing' is meant the reproducing a positive, in which the lights and shades are true to nature from a negative in which they are reversed. The operation, not being attended with the destruction of or injury to the negative, they may be repeated indefinitely, and therefore any number of prints may be taken from the same negative. There are two methods of printing; one consists in copying the negative by means of a lens, the other by pressing it upon a sensitive tablet in a pressure frame, and exposing to direct light. In both cases the light which produces the print is transmitted through the transparent parts of the negative and stopped by its opaque parts."25
Optical printing was also employed by H. Joly,26 T. P. Middleton,27 H. Dorten,28 P. Ulysee.29 C. N. Bennett30 described a plate-titler as follows : "This is really a combination of printer and ordinary still view projection lantern. The original title laid out in white letters on a black velvet ground is first photographed upon a glass plate by means of a downward-pointing still view camera. The black letter photographic title transparency so obtained is then centered before the condenser of a projection lantern contained within the printing cabinet. By means of a suitable objective lens, also within the cabinet and situate between the title transparency and the printer gate, a sharp image of the title wording is thrown upon the threaded positive stock. Such a form of photographic printing is also known as "reduction titling" as in contradistinction to "contact," where the usual kinematograph negative is employed before the positive stock in the printer. With "reduction titling" it will be seen that only the single thickness of unprinted stock is threaded in the gate, the place of the negative film being taken up by the projected image of the title borne upon the transparency in the focus of the interior projection unit." O. Fulton31 described optical printing for double-coated material.
Some patents, which have considerable bearing on the subject were granted to W. R. Schwab32 and it is stated in the specification: "My present invention relates to improvements in photographic apparatus and more especially to the type adapted for the reproduction of books, records and other documents, and the primary object of the invention is to provide a simple, improved and more efficient apparatus of this type whereby accurate photographic reproductions may be made quickly upon oppositely sensitized surfaces such, for example, as a paper or film sensitized upon both or opposite sides, the exposure of both sensitized surfaces being produced by the use of a single lens which splits an object into two images of two objects upon the respective sensitized surfaces. In reproducing records or other matter contained in books, the objects upon the two open