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 397
ston's meniscus (fig. 62) came to be recognised as a means of extending the definition ; and in 1840, Chevalier, a Paris optician, still further improved it by a different method of achromatising the lens. But in the following Fig. 60. Fig. 61. year, through the agency of Voigtlander, a practical… … Fig. 62. Fig. 63. the finest portrait lenses of the present day. The above (fig. 63) is a sketch of Petzval's original portrait lens : — The dark shaded parts are crown, the light shaded parts are flint glass, and, as will be seen, the front combination exists of a double- convex crown cemented to…
Photography
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