An introduction to the science & practice of photography (1888)
Jones, Chapman · London : Iliffe & Son · leaf 90
86 THE SCIENCE AND PRACTICE OF PHOTOGRAPHY. (plano-convex, convex meniscus) will produce the same effect with either side toward a luminous object; indeed, if such were the case, it would be contradictory to the previous statement. If the luminous point is moved further from the lens, the… … Fig. 14. lens as the principal focal point, the point of light pro- duced on the other side of the lens will be at exactly the same distance from the lens. Any such pair of points are called " conjugate foci." Any number of luminous points will be simultaneously reproduced by the lens, and there-…
Photography
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
![An illustration from Vnderweysung der Messung : mit dem Zirkel vn[d] Richtscheyt in Linien, Ebnen vnnd gantzen Corporen (1525)](https://img.insideoutlibrary.com/img/200/ia-vnderweysungderm00drer-30-50.webp)
