A dictionary of photography for the amateur and professional photographer (1889)
Wall, E. J. (Edward John), 1860-1928 · New York : E. & H.T. Anthony · leaf 112
DICTIONARY OF PHOTOGRAPHY. 102 mathematician of Vienna, was made and introduced commercially in 1 84 1. This was the portrait lens ; and it is a remarkable fact that it is the model for the finest portrait lenses of the present day. The following (fig. 7) is a sketch of Petzval's original portrait … *ig. 6. Fig. 7. lens : — The dark shaded parts are crown, the light shaded parts are flint glass, and, as will be seen, the front combinat'on exists of a double convex crown cemented to a double concave flint, and the back of a flint concavo-convex separated from a double convex lens of crown…
Photography
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