Photographic optics and colour photography [electronic resource] : including the camera, kinematograph, optical lantern, and the theory and practice of image formation (1909)
Johnson, G. Lindsay (George Lindsay), 1853-, Parsons, John Herbert, Sir, 1868-1957, donor, University College, London. Library Services · London : Ward & Co. · leaf 212
i88 PHOTOGRAPHIC OPTICS handled. The Busch Optical Co. make a useful " up-and-down movement " shutter which gives about half as much exposure to the sky as the foreground. Dallmeyer's Packard Ideal Shutter (Fig. 141) is one of the Fig. 141.— The Packard Ideal Shutter. best shutters of this class.… … Fig. 142.— Dallmeyer's Central Shutter. releasing a ball connected with a tube. They are much used in studios, since a portrait can be taken without the sitter being aware of it, but they cannot be worked much under half a second, except in the case of Dallmeyer's Central Shutter which
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