File:The American annual of photography (1918) (14780946402).jpg

Identifier: americanannualof1918newy (find matches)
Title: The American annual of photography
Year: 1918 (1910s)
Authors:
Subjects: Photography
Publisher: New York : Tennant and Ward
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University

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MAfiK £XT£/^SlO/V HERE Figure 4. behind the lens and the original or copy in front, which givesa reduction instead of an enlargement, though still in thesame ratio. Where we should get a four-diameter enlarge-ment we obtain a one-quarter size reduction, and so on. En-largers differ a good deal in design, and in some cases it maybe more convenient to mark the baseboard than the exten-sion. Passing from flat subjects, such as copies, to those includ-ing a number of objects at different distances, the photogra-pher is apt to get puzzled as to what factors really regulatefine definition. We hear a good deal about depth nowa-days, and the would-be purchaser of an expensive anastigmat 218
Text Appearing After Image:
ELLIOT STUDIO. 219 is repeatedly assured by photographic friends that he will notget the same depth of definition as that given by his presentR.R. lens of similar focus, unless he stops down the anastig-mat to the same aperture. Hereupon, if he is one of thosewho love needle-sharp negatives and is never of necessityobliged to work in a bad light, he most likely fancies thereis nothing to be gained by the change, and remains faithfulto his old lens. Now, there is a subtle fallacy here. Though it is perfectlytrue that the depth will be the same in the two lenses of thesame focus, at the same aperture, it does not follow that thegeneral definition will be identical. It is not only for extrarapidity that one pays more when buying an anastigmat. Be-sides its ability to be used at a larger aperture than the R.R.lens, which may be regarded as a reserve power, only per-haps needed in a dull light, or for subjects in rapid motionwhere the exposure has to be cut down, there are other solidadvan

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