P3D Stereo Base, Truth, Beauty

[Michael Georgoff <Michael_Georgoff@xxxxxxxxxxxxxx>]

Bruce, thanks!  I pretty much knew I could count on you to gnaw the
cheese on-list.  You did say "There was a real thorough analysis in a
recent "Stereoscopy" - I've forgotten the authors and the issue and it
isn't at hand."  Bruce, can you dig this up?  Anyone else on the list
have any info on the article?  (Was it perhaps the Bercovitz/Spicer
piece?  What I found was noted "A Comparison of Camera Base Calculation
Methods Originally published in "Stereoscopy", the Journal of the ISU.")
So, Bruce, if you would kindly saunter over to
http://www.werple.net.au/~kiewavly/bases.html and let me know if that
looks like what you were thinking of, I'd be a grateful guy.

Back to the issue of stereo base. There are a few folks whom I consider
very accomplished at stereo photography, and very distinguished, I might
add, (whom I often refer to as "the Tribal Elders") who are from the
"Don't Worry, Shoot Happy" school of thought.  This surprised me, I
thought it was required that you go though a "trial by math".  Some of
the Modern Masters have a "I don't need to steenkin' math" attitude.
Some have told me they started with a bit of math long ago, but don't
use it currently.  I believe that these folks, based on experience, have
"gotten it" and now shoot intuitively.  Some probably by trial and error
have learned what works, and if you put it to a "math test" (which
really comes down to on-film-deviation), it would stand up.  And, these
folks have mounted enough in their day to have gotten past that
difficult-to-learn stage.

Bruce said:

>Seems to me that (aside from the 1:30 rule) the Holy Grail of base
>calculation is to make darn sure you don't exceed an on-film deviation
>of 1.2 mm on 35 mm film - on-film deviation being the difference
>between the far-point separation and the near-point separation.  Most,
>if not all the systems I have taken the time to dig into seem to bow
>to that figure, with minor exceptions.  But I might be wrong. ;-)

In other words, doesn't seem to matter how you get there, it's all means
to an end, the end being "though shalt not exceed 1.2 mm on film
deviation on the 35 mm format, or verily, your fellow man and woman may
have convergence problems."

Regarding Bruce's first tabletop attempt, wherein he shot successively
larger spaced base shots to get an eye pleasing pair.  Or Andrea's " I
shoot at least 3 shots from different positions and match the best two.
No measurements, no calculations, no headache."  Trial and error.

Bruce said  "... Which I guess puts me for now in the "don't worry,
shoot happy" class.  But it's an uneasy state."  I know what you mean.
It would be simpler if there were a generally accepted universal,
empirical truth on the geometry of stereo that we could rely on.  There
only seems to be the end criterion of 1.2mm OFD.  (Kinda reminds me of
comparative religion or philosophy, seek your own truth.)

There are musicians who can't read music and never studied theory,
painters who did not have schooled backgrounds, etc, etc.  There are
stereo photographers who've never bothered with math.  Doesn't mean the
music, the painting, the stereo photograph is any less beautiful.  Use
what works, doesn't seem to matter which route you take.

Andrea mentioned getting three different answers to her question on
where the measurement to the subject starts from, in the calculation of
stereo base.  Many answers, especially many complex answers,  to a
seeming simple question by a beginner (not to imply that you are,
Andrea!) can certainly dissuade a beginner from moving forward.  When I
first started my subscription to P3D, I thought I'd never get it. what
with all the Big Boys rasslin' out base and ortho and such.  Andrea, if
you're still working on that FAQ for the beginners, maybe you should
include a bit about avoiding complex routes to simple achievement, you
don't need to go deep at the beginning.  And, don't let the deep theory
mean you can't "just do it" and be happy.

I'd be curious to hear from others.  How do you do stereo? 
A) Don't Worry, Shoot Happy.  
B) 1:30.
C) Some math.
D) As much math as I can get
E) Other (specify)


And, are you/are we?:
A) Stereo photographers
B) Stereographers
C) Stereoist
D) Stereo nuts (as suggested by certain spouses)

Let's keep in lively in here!

Michael Georgoff
San Jose, CA


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