Wilson's quarter century in photography : a collection of hints on practical photography which form a complete text-book of the art (1887)
Wilson, Edward L. (Edward Livingston), 1838-1903 · New York : E.L. Wilson · leaf 49
ject B is similarly brought to C, and the line 0 P' is drawn. Next, the triangle 0 P P' is completed by setting off the base P P', and the legs, 0 P, 0 P', are evidently the focal distance. (For simplicity of measured from the nodal points Pand P, and the two conjugated foci are F P and F P,… … It is often necessary to know the focal length of a lens or a combination of lenses, especially in i)hotography ; but if no plano-convex lens of known focal length is at hand, for the purpose of comparing the size of the image, the following way may be adopted: first, focus the lens for a very…
Photography
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