Marion and Co., author · London W. : Marion and Co., 22 and 23 Soho Square · leaf 116
a lens of double the focal length of the whole. (See Chapter on Optics.) We now come to the process of exactly focussing the view. We use the lens' full aperture, — that is to say, we put no stop into the diaphragm slit, or if the dia- phragms be rotary we turn the diaphragm disc so that the… … Now we have to select the diaphragm to use. We shall probably perceive that, although the principal object is now quite sharp, neither the distance nor the foreground is so. We place the stop with the largest aperture in position, when we shall perceive a notable improvement on the definition of…
Photography -- Handbooks, manuals, etc
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
