P3D Re: 7-perf Red Buttons

[Eric Goldstein <egoldste@xxxxxx>]

John Fairstein wrote:

> But I just received a Themelized Red Button viewer which works fine with
> 7-perf! But that's not all -- I also just received a Super Themelized
> 8-perf Red Button viewer which features a new reflector. This reflector
> is an amazing piece of work as it provides even illumination across the
> 8-perf aperture.

Peter Abrahams says it well:

> If you open up the slide carrier windows, you can see 7 perf, but
> anywhere near the edge they are not at all sharp.   They are sharp enough
> in the middle of the field and become blurry near the edge.....not right at
> the edge, but maybe 2/3 of the way to the edge.  This is nowhere near as
> good as could be, a flat field magnifier (such as a high quality loupe used
> to magnify negatives) would give vastly better performance.
> I haven't spent the time to determine whether the doublets in the RB suffer
> from astigmatism, coma, or field curvature, (likely the last).  I haven't
> checked out their color correction or contrast.  They are pretty decent
> lenses, but a viewer with the best available lenses (snip) could be far better.

Archomatic doublets are only sharp and flat for about 65% of the center
field; the edges go soft and distort (pincushin?). You can see some of
this with 5 perf slides, but it obviously becomes much more pronounced
with 7-8 perf. They are not close to equaling the performance of the
camera optics...

This is a problem in that as we know stereo viewing is much closer to
the real-time "scanning" type of viewing which we do in real life, and
folks will naturally want to look into the backgrounds and the corners
to see what's what. This actually relates back to George T's recent
question regarding "normal" field of view, which really relates to the
medium being viewed and is more a cognition issue than one of
"equipment" or eyeballs. In 2-D photography the field of view is
realistically a matter of what's in focus, what's lit, composition, etc.
In 3-D, the FOV is "supposed" to be and is typically the entire window
if all is on focus, just like in real life. Of course, we can blaspheme
and creatively narrow the 3-D FOV through the use of selective focus,
lighting, etc, but seemingly few do...


Eric G.


------------------------------

End of PHOTO-3D Digest 2486
***************************