Lummer, O. (Otto), 1860-1925, Thompson, Silvanus P. (Silvanus Phillips), 1851-1916 · London, New York, Macmillan and Co., 1900 · leaf 60
LUMMER’S PHOTOGRAPHIC OPTICS 44 CHAP. even with a relatively large aperture -ratio it gives sharp images ; it has the convex side (of the crown glass) turned outwards toward the light. If it is reversed, so that the concave side is turned outwards toward the light, it gives a definition that is… … Fig. 9. Fig. 10. The two Typical Forms of Old Achromats. Daguerre took his first photographs in the year 1839 by the help of such a meniscus lens.^ The second typical form. Fig. 10, which is a meniscus shape, consisting of a positive meniscus of crown combined with a negative meniscus of flint, if…
Photographic optics
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