Photographic Optics: Including the Description of Lenses and Enlarging Apparatus (Classic Reprint) Paperback -

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Excerpt from Photographic Optics: Including the Description of Lenses and Enlarging Apparatus The five aberrations of most interest have been the object of our especial care. A radiating point of homogeneous colour) being placed at infinity, and in the axis of a convergent lens, emits parallel rays, which on emerging from the lens do not meet at one point in the axis; and therefore the image of the point is surrounded by a circle of diffused light, called the circle of spherical aberration. If the point is placed some degrees out of the ax1s, the circle of aberration becomes elliptical; and if the point is very obliquely placed, its image takes the form of a comet. We have carefully examined the conditions necessary to reduce this spherical aberration to the minimum by the employment of the diaphragm, or better by joining to the convergent lens a divergent lens, with appropriate radii of curvature, which makes the combination aplanatic, that is, free from spherical aberration along its axis. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.