The dictionary of photography for the amateur and professional photographer (1897)
Wall, E. J. (Edward John), 1860-1928, Bolas, Thomas · London : Hazell, Watson & Viney · leaf 307
moon, and, the focus temporarily fixed, the ground-glass is removed from the frame, and a negative Of a strong contrasted subject is placed in the frame, from which the ground-glass has just been removed. A very good negative, t=r — Fig. 51. if handy, is that of a line-drawing. The eye-piece of the… … Fig. 52. lines of the negative are seen sharp and clear. Now, as the telescope focus has been fixed for infinity, the negative will only appear sharp when it is at the true focus of the lens ; this position is then accurately marked, as shown in fig. 51, in which t is the telescope focussed for…
Photography
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