Elementary optics and applications to fire control instruments (1922)
United States. Army. Ordnance Dept · Washington, Govt. Print. Off. · leaf 41
the distances u and v are measured. When the thicknessof the lens is too great to be ignored, equation 32 will still be true if uand u are measured from the two principal points and if for /wewrite the equivalent focal length. The two principal points lie on the axis of the lens and are… … rays make equal angles with the optic axis. For this reason thesetwo points are sometimes called points of unit angular magnification.The principal ])oints are shown in figure 41 at P, and P... The locations of the two principal points are given bytions: V P ^^ * 1-^ 1 n{r. V..P, t{n-\) tlie…
Optics · Optical instruments · Fire control (Gunnery) -- Optical equipment
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