A Manual Of Photography
Forfatter: Robert Hunt
År: 1853
Forlag: John Joseph Griffin & Co.
Sted: London
Udgave: 3
Sider: 370
UDK: 77.02 Hun
Third Edition, Enlarged
Illustrated by Numerous Engrabings
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LENSES EOK THE PHOTOGRAPHIC CAMERA. 179
tory power of the surfaces so produced that their peculiarities
belong. The adjoining figures represent the varieties.
32
1 is termed a plano-convex lens.
2 is a double convex sens.
3 is formed of parts of two circles of different diameters,
and is called a meniscus lens, or concavo-convex.
4 is a plano-concave lens.
5 is a double concave lens. And
6 is a concavo-convex lens, formed of parts of the inner sur-
faces of two dissimilar circles.
It is not necessary to examine the laws of refraction for all
these forms; the phenomena will be fully understood by an
examination of a few leading points. Whatever may be the
form of a lens, the incident rays parallel to its axis pass
through without suffering refraction, as A A A, « a a, Fig. 33,
All other ravs must have a certain amount of obliquity, and
these all consequently suffer refraction, as the rays a d. Now