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 308
en occupying the middle third of the disc C. If the light be too far away, the ring will have a bluish fringe and will surround the periphery of the disc D. If both centering and distance be correct, the disc on the screen will appear uniformly white. In order to increase the light, a convergent… … Fig. 178. — Perken & Son's Lantern Lens. & Son have produced an excellent form at a very low price (Fig. 178), but one of the many forms of rectilinear anastigmats of large working aperture, F/4 to F/5, is to be preferred, as they have a natter field and, consequently, a better marginal…
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