File:The American annual of photography (1912) (14762796821).jpg

Identifier: americanannualof1912newy (find matches)
Title: The American annual of photography
Year: 1912 (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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d separately, as by parallel vision, and when the resultsare properly presented by the stereoscope, we combine thetwo retinal images by the variable convergence and adjust-ment as when viewing the objects in nature. The lenses ofthe stereoscope should be the same focus as those used in thecamera, then we see the picture at the same angle underwhich it was taken, and the apparent natural size with thecorrect mechanical perspective. If photography could giveus the true aerial perspective—light and shade and color—the correct distance apart for the twin lenses on our camerawould be the interocular distance, which is approximately 2^inches; but as photography has not yet arrived at that degreeof perfection we may increase the centers of our lenses to 3inches for general landscape work. There are cameras onthe market with adjustments for increasing and reducing thecenters of the lenses. These are wrong in principle and leadto confusion and mistakes in practice; then there are advo- 290
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L) W H lis I—I HO t-H cates for long-distance base-lines; i. e., taking the dualpictures from points of sight yards and yards apart so as toincrease the binocular perspective to an unnatural degree.Who ever saw Niagara Falls under such conditions as byone eye at the American end of the suspension bridge and theother eye at the Canadian end? Nature has not provided uswith any adjustment for the interocular distance, and ourfaculty for judging distance by binocular perspective is limited.This is the reason why successful stereoscopists pay attentionto the arrangement of the foreground subjects. For stereo-scopic work alone there is no advantage in using larger platesthan 3^ x 6^ inches, though personally I prefer doublequarter (4^ x 6^) which give the advantage of the largersize for single pictures, and considerable latitude in selectionof foreground when printing from the stereoscopic negatives. There is no technical limit to the vertical dimensions of astereoscopic picture, but the

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