Laurence, Lionel · London, School of Optics · leaf 237
lows that the deviation effected by the various zonesof a lens depends on this distance. In a Cx. lens the varying inclination ofopposite points on the two surfaces, in each meridian, causes parallel lightto converge, in theory, to a point, but actually, the refraction of a sphericallens is such… … Fig. 234. Each zone of a lens has its own focal length, varying from the principalfocus F, for rays refracted in the zones immediately surrounding the prin-cipal axis, to a point where rays A and B passing through the most externalzones, meet the axis. The inability to unite in a single point all…
Optics
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
