P3D Re: Richmond, and Base

[Bruce Springsteen <bsspringsteen@xxxxxxxxx>]

Michael Georgeoff said:
   A mouthful!

His encyclopedic posting on the 31 flavors of base calculation rivals
anything I've seen lately, even from the formidable Dr. T.  He knows
the dangerous characters have all finished "meeting" in Richmond and
are now just "pieces of gingham and calico".  So while the cats are
away, Michael the Mouse didn't just play - he roared!  And he asks if
I'm with him.

I'll nibble this cheese in a small way and see if any of the big cats
are really still around.

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. ;-)

There was a real thorough analysis in a recent "Stereoscopy" - I've
forgotten the authors and the issue and it isn't at hand.  I seem to
recall that several variations of the theoretical ideal were offered,
based on situational preferences, but a general approval of 1:30 as
good enough for most situations, then lots of graphs with scary
logarithmic scales and swoopy curves.  I'm sure that article must have
gotten a good chewing over on P3D, but I'm unable to find anything now.

Andrea's question about where to measure from was on my mind too.  I
only have a 35-70 zoom on my SLR and was foolishly measuring from the
foremost lens to the near point on my main subject - 15 inches.  I
took a series of shots in this, my first close-up tabletop attempt,
beginning with the 1/2 inch (1/30th) base, then increasing 1/2 inch
for each succeeding shot, perhaps up to 2.5 inches.  The pairs that
finally pleased my eye were more like 1.5 to 2 inches base, FL on lens
near 50, so I have no idea what happened.  Which I guess puts me for
now in the "don't worry, shoot happy" class.  But it's an uneasy state.

The only other thing I know is Andrea said in her preying mantis macro
article in the PSA journal that she was shooting with no mathematical
contemplation whatsoever, much to her husband's disgust.  The only
samples of her results I have seen looked gorgeous, so ignorance may
indeed be bliss, at least for the lucky.

That's all I know about this so far.  And half of it is probably wrong.

Bruce 







  
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