History and Practice of the Art of Photography by Henry Hunt Snelling
page 48 of 134 (35%)
page 48 of 134 (35%)
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and more or less distinctness and clearness of delineation obtained.
These caps alway come with Voitlander instruments and should be secured by the purchaser. Though the single acromatic lens answers very well for copying engravings; taking views from nature or art, for portraits the double should always be used. The extensive manufacture of the most approved cameras, both in Europe and in this country, obviates all necessity for any one attempting to construct one for their own use. Lenses are now made so perfect by some artisans that, what is called the "quick working camera" will take a picture in one second, while the ordinary cameras require from eight to sixty. The camera in most general use is that manufactured by Voitlander and Son of Germany. Their small size consists of two seperate acromatic lenses; the first, or external one, has a free aperture of 1 1/2 inches; the second, or internal, 1 5/8 inches; and both have the same focus, viz: 5 3/4 inches. The larger size differs from the smaller. The inner lens is an achromatic 3 1/4 inches diameter, its focal length being 30 inches. The outer lens is a meniscus--that is bounded by a concave and convex spherical surface which meet--having a focal length of 18 inches. For every distant view, the aperture in front is contracted by a diaphram to 1/8 of an inch. By this means the light is reflected with considerable intensity and the clearness and correctness of the pictures are truly surprising. THE AMERICA instruments are constructed on the same principle and many of them are equally perfect. Mr. Edward Anthony of 205 Broadway, New York city, has constructed, and sold cameras fully equal to the German and for which Voitlander instruments have been refused in exchange by the purchaser. |
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