Art of photography : instructions in the art of producing photographic pictures in any color and on any material, for the use of beginners and also of persons who have already attained some proficiency in the art, and of engravers on copper, stone, wood, etc. (1854)
Halleur, G. C. Hermann, Schubert, F. (Franz) · London : J. Weale · leaf 33
18 THE ART OE PHOTOGRAPHY. 5 I to obtain a good focus. Another advantage is the vertical mobility of [ the object-glass, whereby the object to be portrayed may readily be | brought into the centre of the field of vision. The posterior part of i … the apparatus is fastened to a movable plate, which may be screwed fast on the ground-board, at a longer or shorter distance from the object-glass ; by which means the operator is enabled to employ, if need be, object-glasses of different focal lengths. The whole apparatus is so arranged, that it…
Photography
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