A dictionary of photography for the amateur and professional photographer (1889)
Wall, E. J. (Edward John), 1860-1928 · New York : E. & H.T. Anthony · leaf 221
double lens of about i\ or 2 ins. focus mounted in a sliding brass tube, a mirror at an angle of 45 degs., and a piece of ground- glass on the top, with a shade. In the preceding diagram, show- ing the arrangement, abcd is a rectangular box of card or wood; L, lens in sliding tube; M, mirror; G,… … A on it as shown in the diagram ; then when the eye is placed at A and looking along a b, the object when opposite this will be in the centre of the plate, and cad is the angle included by the lens. Or a double convex lens of exactly the same focus as the lens may be mounted on the front of the…
Photography
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