Pentax Loupes (was Re: Nice Rig, HP, Ideas)

[erker@xxxxxxxxxxxxxx (Greg Erker)]

>I was fondling the Pentax Lupe again yesterday at a camera store. From the
>loupes I've tried, I find it one of the best. Project # 54,452 in my books
>would be to scoop a pair of these and rig them up to be BOTH the taking
>lenses and the viewing lenses for a wide-angle 2 1/4 stereo camera. I think
>they are around 50-55mm, correct? I figure if they were reversed and stuck
>in front of f32 apertures you'd not need to worry about focusing, and the
>black square casing you make to go between the lenses and the slide would
>invert into a lens shade for taking.  Anybody gotta couple they wanna give
>away for the experiment?  They'd be great for Lester's new camera as well,
>giving a close-to-ortho immersive effect.

  One jab I've heard about using 2 element closeup
lenses for macro vs extension tubes or a true macro
lens is "you wouldn't put a 2 element lens on your
camera so why would you put one on the front of your
lens". Or words to that effect.

  It's a bit of a bogus argument for macro since
a 2 or 3 diopter CU lens isn't very strong compared
to a 50 or 100mm macro lens. But it does raise the
question of whether you can use a loupe (2 to 4 elements?)
as a camera lens.

  Stopping down to f32 helps but not all abberations
are corrected by stopping down. Anyone have any
thoughts on Sam's idea?

  One problem would probably be the large leaf shutter
you'd need since the point you'd normally place your
aperture and/or leaf shutter may be buried inside
glass.

  My recollection of the Pentax loupes is that they
don't even cover mounted MF (50x50mm) images. But
I guess that may be good for the immersion type stereo
idea.

  To get quality images you may be better off taking
them with 55mm Mamiya TLR lenses. And then viewing them
with the Pentax Loupes.

Greg