[photo-3d] ofd calculator

[boris@xxxxxxxxxxxx]

Hi everyone!

There was a time last year when the discussion turned extensively to
calculating on film deviation, and what maxima are permissible, etc.  I
largely ignored those discussions, because I knew they were not for me: I
had always shot subjects of about the same size, relatively nearby; and for
me shooting with something close to a "normal" interaxial spacing (i.e.
close to 2.5 inches) with a "normal lens" (close to 50mm f.l. for 135 film)
was something of a religion!  I shot all my slides the same way, they
mostly looked good in a viewer (and I suppose projected), and that's all I
cared about.

But you know how it is.  Times change, science and life present new
discoveries and opportunities, or else curiosity and boredom drive men to
explore uncharted waters.  If they are not gobbled up by deep sea monsters,
religion must keep up, evolve, or be cast aside useless.

Most of the last year was spent experimenting with anaglyphs - suddenly on
film deviation, or I should say on _print_ deviation, became an important
issue.  Now I find myself shooting for dual (or even triple!) purposes: for
slide dupes (for viewers), for anaglyph prints (some large, some small)...
and who knows what formats the future may bring.

Now I ask the members of this list, or perhaps _the_ member, who
presented/proposed some kind of on film deviation calculator - was it ever
made?  This would be a device, preferably portable without too many vacuum
tubes, that would correlate stereobase, near point and far point distance,
and lens f.l. with on film deviation.

I seem to recall a spreadsheet mentioned, but I don't know anything about
them, except all those collumns and rows make my head spin.  Maybe someone
has a routine I can program into my HP 15C, buried in some drawer around
here, a relic of my college days.

I remember a rule of thumb that I found pretty attractive, and that works
well when just shooting for slide viewers (or stereocards, I suppose): set
your variables (the last one being stereobase) so that the near and far
points deviate just about the width of the focussing screen split prism (if
your focussing screen has one).  That's a nice rule, but I need a more
rigorous solution that will allow me to set for any on film deviation,
sometimes small, other times large - plus I may not have the option of
getting my subject(s) to sit still enough to make measurements right on the
focussing screen.

Should I have searched the archives?  Sure, but this may lead to fun discussion.

Thanks in advance for your help!

Boris


- Science is the part of culture that rubs against the world.
-
-                                     Stanislaw Lem, _His Master's Voice_

Boris Starosta                        boris@xxxxxxxxxxxx
Stereoscopic Art & 3-D Photography    http://www.starosta.com
usa - 804 979 3930                    http://www.starosta.com/3dshowcase



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