P3D Re: Pentax beam spitter: please describe

[SHIELDS@xxxxxxxxxxxxxxxxxx]

You already have a couple of replies to tell you that the Pentax is
not adjustable, has a stereobase of 70mm, and usually 49mm threads,
although it also comes in 52mm. And that it is really meant for 35mm
format--24X36mm. I was interested to learn that there was an earlier
version that locks in place--the constant checking to make sure it
is level is annoying.

I did want to add that it is an excellent unit and, used on my
SLR, is my main picture taker. The majority of the stereo slides
I have were taken using it, and they are very good. I get raves
all the time about them. I'm very pleased. But the apertures
available using it on a 35mm are good, useful ones (f/4, f/5.6,
f/8).

I've heard a few reports of some kind of beamsplitter success with
larger formats, but they had to stop down to f/11 and f/16. If you
can't live with that (and maybe you can, using a faster film in
such a large format), then you shouldn't be considering it. And
even that might not work. The Pentax isn't meant for that use.

FWIW, since the Franka has been mentioned, its adjustable mirrors
_might_ help using it on a larger format--I don't know. I have one
on order, but it has _second surface mirrors_ and I expect to
replace them, which could be a beastly job. I have lined up a source
of front surface mirrors, and hope it all works. Second surface
mirrors cause ghosting because of the reflections from the front
of the mirror glass--not a formula for the best quality.

Mark Shields

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