Historic Camera Collector Club
|DICTIONARY OF PHOTOGRAPHY
by E.J. Wall
wide-angle aplanats, some of the finest lenses of the day; and in figs. 21 and 22 are shown two more of Steinheil's lenses, which work at f/2.5, No. 21 being for groups, No. 22 for portraits.
In fig. 23 I am enabled, by the kindness of Messrs. Perken, Son, & Rayment, to give a sketch of the Euryscope lens, which
is composed of two symmetrical combinations of flint glass, and works at an aperture of f/6, a great gain for rapid work. These lenses are perfectly free from spherical and chromatic aberration
and distortion, and for such a large aperture have a wonderful depth of focus, with an extremely flat field. Within the last few months Mr. Dallmeyer has introduced a rectilinear or nondistorting single lens, which works at a large aperture, which is absolutely free from distortion, without astigmatism, and a very flat field (fig. 24).
Thus far I have endeavoured to give some slight sketch of the leading and fundamental forms of all lenses, and whilst numerous modifications exist which may be considered advantageous by some, they are all made on the principles involved in one of the above.