An introduction to the science & practice of photography (1891)
Jones, H. Chapman (Henry Chapman), 1854- · London : Iliffe & Son · leaf 129
in working at twice the rapidity, i.e., j/.3. The diaphragm is, of course, larger, and it is placed further from the lens to give greater flatness of field (fig. 21). Fig. 21. The anterior convex meniscus is of extra light flint instead of crown, and the anterior surface of this lens is less curved… … Fig. 22. The two anterior lenses are cemented, and form a combin- ation of very long focal length. This lens is intermediate in rapidity between the two last described, the maximum aperture recommended when good definition is desired being /. The especial feature of this instrument is that it is…
Photography
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