Re: [photo-3d] To math or not to math?

["John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>]

----- Original Message -----
From: "Dr. George A. Themelis" <drt-3d@xxxxxxx>
To: <photo-3d@xxxxxxxxxxxxxxx>
Sent: Wednesday, February 28, 2001 4:26 AM
Subject: [photo-3d] To math or not to math?

> John, the thick photo books have been replaced by advanced
> calculators.... Sorry, I cannot resist but quote this message
> that came from the MF list (MF stands for Medium Format, not
> Mathematical Formulas!!!)  I did not write this!!!  Email Paul
> Talbot if you would like to join the MF stereo list.
>
> Here is the quote.... enjoy!!!!  -- George Themelis
>
> excerpt from:
> http://www.pauck.de/archive/mailinglist/mf3d/mhonarc/msg04004.html

The description referred to above (which I removed, Paul!) is great.  It
should be framed and hung on the wall in every stereo club.  I wonder if the
writer has ever done stereo photography of birds or airplanes or sports, and
if the subject was still around by the time that the calculations were
completed (even with an advanced calculator)!

The point that I like to make with the math mavens, is that: 1.) usually it
is not necessary, and 2.) it can actually be misleading and
counterproductive.

I have shelves full of books on stereo photography written all the way from
the late 1800's to the present time.   Many of these, possibly most, have
tables in them purportedly showing where to set convergence for different
focal length lenses (or in some cases, a specific focal length lens).  The
interesting thing is that I have yet to find two books where the tables are
identical!

So which one is right?  They all are.  If you take any particular setting,
it is possible to find a subject (and viewing condition) for which that
setting works.  The problem with assigning numbers to these things is that
stereo photography is very subjective.  What works beautifully for one
subject at one distance with one foreground distance and one background
distance, may not work at all for another with identical distances.  How do
you come up with a mathematical formula that takes into consideration ALL of
the variables: color, texture, subject size, homogenous patterns, geometric
patterns, strong vertical lines, intermingled depth cues (or lack of them),
subject motion (and how fast in what direction), etc., etc.???

Better to go out and start shooting pictures.  Learn from experience.

And Dr. George: Thanx muchly for the MF list info; I will write to Paul re:
this.

JR




 

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