P3D Re: Realist vignetting

[aifxtony@xxxxxxxxxxxxx (Tony Alderson)]

At our SCSC meeting last night, I asked Charlie Piper about the vignetting
problem on the KinDar/Hyponar macro lenses, and the Stereo Realist.
According to Piper, the lenses do not quite have adequate coverage for the
format.  As I understood him, they are not quite wide enough.  He used the
analogy of looking thru a pipe, and how your view is obscured by the other
end.

I have a Hyponar lens that Piper modified for the original owner to
eliminate the vignetting. He did about one hundred of these conversions.  A
particular problem with this design is that apertures are in front of, not
inside, the lens triplet.  Basically, he replaced the original lenses with
lenses from the Wollensack stereo camera.  This meant machining new lens
barrels and rebuilding the unit.

So to fix the vignetting on the Realist 3.5, you would have to replace the
lenses.  Most stereo cameras of the period do not vignette, so this was an
avoidable problem (the Revere also vignettes).  But with ASA 10 film,
nobody used f16 anyway.  Even today, f16 on a Realist doesn't get you much
but exposure convenience.  f8 has all the depth of field you can handle for
projectable slides, so you won't see a sharpness difference at f16 vs. f11.

Tony Alderson
aifxtony@xxxxxxxxxxxxx




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