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 176
o use a flap- shutter attached to the lens mount, and hinging above it. This can be lifted up and allowed to drop by a pneumatic ball, so that any ratio of exposure one pleases can be given to the fore- ground and sky respectively (Fig. 112). Busch makes an excellent pneumatic shutter (" Skyshade… … Fig. 112. — Flap form of Skyshade Fig. Ill Shutter. in ortochrome work, as without some such screen the skies are invariably spoilt through over exposure. 3. For the purpose of reducing Aberrations and thereby limiting the Size of the Circles of Confusion.- — This was of far more importance in the…
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