Platinotype : its preparation and manipulation (1895)
Abney, William de Wiveleslie, Sir, 1843-1920, Clark, Lyonel · London : Sampson Low, Marston & Co. · leaf 152
e beam of the condenser falls within the lens ; so long as it does not travel outside, it does not matter if it is not always quite central. Supposing the lens to be of slightly too long or too short a focal length for the image (Fig. 5) of the necessary size, the focus of the condenser lying… … Fig. 5. be seen that the position of Fl9 the focus of C2, can be caused to recede or approach C^. The further F2 is from it, the shorter will be the focus of Cx, and the closer it is (of course, within limits), the longer will be the focus. Hence Cx is placed at such a distance from the condenser…
Photography
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