P3D beamsplitters and distortion

[SHIELDS@xxxxxxxxxxxxxxxxxx]

Hi!

One of the things that concerned me when I was first considering getting
a beamsplitter was the issue of distortion. I knew that if my lens had
linear distortion (either pincushion or barrel), it would mean the left
and right halves of the image would not properly line up with each other.
In fact, my first trials were with the Olympus 40mm f/2, which because
of the compromises involved in making it compact, has a good bit of
pincushion distortion. I was not pleased. The focal length was also too
short, giving me crazy ghost images off to the side.

But the Olympus 50mm f/1.8 was a different story. I didn't go and dig
out a distortion chart for the lens, but I tried it and I liked the
results. I would say in general that the 50mm f/1.8 normal lenses on any
given camera are likely to be good in terms of all sorts of distortions
and aberrations, as compared to the f/1.4 or to any other focal length.
 
I have heard complaints that the Pentax beamsplitter viewer doesn't have
enough magnification. Perhaps they were trying to minimize the effects
of possible lens distortion. I can well imagine that more magnification
might look good, but I'm happy with what I have.

Mark Shields

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