Re: format/mounting questions

[P3D John Bercovitz <bercov@xxxxxxxxxx>]

Ted G. writes:
 
> question B) i have been doing some 35mm slide bar work, and 
> would like to figure a way to view them in my Dr. T. modified 
> Kodaslide II (soon to arrive, i hope) viewer.  Has anyone tried 
> using the European 'Extra-Wide' 31.5x23mm mounts for full frame 
> 35mm transparencies, sacrificing the required amount of space at 
> the side?  Or the RBT "full frame" mount$ ?
 
I've tried the RMM/Spicer mounts and they work great!  The excess 
width cut off takes care of the stereo window.  Actually, I've 
done it with both their 31.5x23 Twin SLR and their 28x23 7-Perf 
mounts.  Both mounts work fine but the 28 wide is an easier width 
to view in a carved-out standard viewer.  RBT makes a beautiful 
mount, as is well known.
 
> question III) what is the perceptual change from viewing slides 
> made with a 55mm lens on full frame 35mm film, when mounted as 
> Euro 'Extra Wide' pairs and viewed in a Kodaslide II (i don't 
> know the FL of the viewing lenses).  I figure that in close up 
> work i should lose some film width anyway, due to non-identical 
> coverage in each picture.  But i don't know what the perspective 
> change would be given the FL of the viewer lenses vs the FL of 
> the taking lenses.  The viewer was designed for roughly 35mm 
> taking lenses, i assume.  Does the view just appear closer when 
> (infinity subject distance) images shot with a longer FL are 
> used?
 
That's a pretty complicated question.  The underpinning of stereo 
vision (IMHO) is geometry but then you have to add a heavy dose of 
the visual system's "horse sense".  In other words, the visual 
system is smart, plenty smart, and will make the best of a bad 
situation.  However, it pays in ease of viewing to keep the 
geometry correct.  For a look at the geometry, use anonymous ftp 
or www to:
 
ftp bobcat.etsu.edu
 
Then:
 
cd pub/photo/photo-3d/technical
 
Then get:
 
orthomag.gif
orthosep.gif
 
Orthomag answers the question you're asking while its companion, 
orthosep, may answer a future question.
 
Lastly, if you're going to be taking closeup slidebar pairs, 
you're going to need to be careful about how much total depth is 
in the scene.  Naturally I recommend the Spicer/Bercovitz formula 
8-) [ask me off-list about it if interested] but there are 
others.
 
John B


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

End of PHOTO-3D Digest 1279
***************************