The dictionary of photography for the amateur and professional photographer (1897)
Wall, E. J. (Edward John), 1860-1928, Bolas, Thomas · London : Hazell, Watson & Viney · leaf 399
own in fig. 6i, with which extremely small diaphragms are necessary to reduce spherical aberration. This was improved on by Grubb, and his lens is shown in fig. 66, in Fig. 67. Fig. 68. which a crown-glass lens of meniscus form is presented to the object, and is cemented to a flint meniscus. This… … Fig. 69. Fig. 70. between two positive crown-glass lenses. This enabled a much larger aperture to be employed, and eliminated spherical aber- ration. Marginal definition and flatness of field were both improved. To obviate distortion, many doublet lenses were introduced, that of Mr. Ross being…
Photography
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