An introduction to the science & practice of photography (1895)
Jones, Henry Chapman, 1854- · London, Iliffe, Sons & Sturmey Ltd · leaf 126
and a change in tem- perature means a change in refractive power. In 1861, T. Ross bought the patent rights of this lens, and issued copies to the public. Other fluid lenses, as they are called,, have been constructed. In i860, the celebrated triplet of J. H. Dallmeyer was constructed. This was the… … Fig. 25. achromatic, and the central combination, which is diverging or negative, serves to flatten the field. By removing the central combination the focal length of the whole lens is reduced, and its aperture, originally f/15, is enlarged sufficiently for portraiture. The need for a…
Photography
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