Excerpt from The Lens: A Practical Guide to the Choice, Use, and Testing of Photographic Objectives Thanks are here tendered to several persons and firms for the use Of blocks, viz., to R. J. Beck, Ltd. (for fig. 10) J. H. Dallmeyer, Ltd. (fig. Ross, Ltd. (figs. 73, 74, and Carl Zeiss (fig. W. Thomas (figs. 114 and and Miss Evelyn Boden (fig. Professor F. J. Allen has permitted the reprint of the notes on angle of view, and has contributed some others, and Mrs. Catharine Weed Ward has supplied the illustrations on pp. 109 and 110. 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.