Re: Stereo Duplex

[P3D Eric Goldstein <egoldste@xxxxxx>]

> Bruce Rosenberger asks how close can his newly acquired Stereo
> Duplex focus with the aid of auxillary closeup lenses?


The reciprocal of the diopter is the infinity focus point expressed in
meters. A +1 lens focuses at approx. 39 inches (1 meter) when the camera
is set to infinity focus, a +2 gives about 19-20 inches (1/2 meter), a
+3 gives about 13 inches (1/3 meter), +4 focuses at about 9-10 inches
(1/4 meter), etc.

By focusing the camera lens to distances closer than infinity and by
stopping down, in practice the diopter lenses yield a focusing range
around each of these distances.

Eric G.


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