The optics of photography and photographic lenses (1904)
Taylor, J. Traill (John Traill), 1827-1895, Everitt, P. F · London ; New York : Whittaker & Co. · leaf 196
A N A S TIG M A TIC LENSES. 184 the same. Dr. Schroeder tried not only triple, but double and quadruple combinations, for the construction of the central dialyte. In 1890 a patent was granted to Dr. P. Rudolph for a series of lenses, which are now known as ‘ Protars. ’ … The back is a new achromat, Fig. 55. or a more complex construction equivalent to a new achromat. Fig. 55 represents the simplest form of the Protar. By referring to page 69, it will be seen how near Thomas Ross and Thomas Grubb came to this type, but the crown glass ■ 1 necessary for the…
Photographic optics · Photographic lenses
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