ng,since lenses of the same power, but of different shape, have not the sameback focus, consequently do not form the image of a far distant object at thesame distance from the rear surface, and are therefore not interchangeal)le.The diagrams l>elo\v show a double convex and a meniscus convex… … Therefore, the present way of designating the [)ower of lenses by reciprocalsof focal length is not correct, because it measures something which is reallyof no value to the proper performance of the Urns. The power of a lens, up to the present time, has been measured by com-paring it with that of a…
Lenses · Eyeglasses
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