Re: A suggestion on how to match lens for a Realist

[P3D John Ohrt <johrt@xxxxxxx>]

P3D Dr. George A. Themelis wrote:
> 
> >From: P3D John Ohrt  <johrt@xxxxxxx>
> 
> >Shoot a normal stereo set. (set #1)
> >Mount the Realist on a slide bar. Shoot a normal stereo set. (set #2)
> >Slide the interpupillary distance of the Realist.  Shoot a normal stero
> >set.  (set #3)
> >
> >Mount set #1 as per usual.
> >Use sets #2 and #3 to compose stereo pairs such that each pair was taken
> >by the same lens.
> >
> >If you can see any difference, start swapping lens!
>  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> "Any difference" where?  Between different pairs??? Since sets 2 and 3 were
> taken with the same lens they should be identical always.  It will be
> almost impossible to tell the difference between the two if the difference
> is small.  So we are left with set 1 which is the only set that you need
> to have to compare the two lenses.

You have three stereo pairs taken with the same pupillary distance,

set #1

right lens set#2 & set#3

left lens  set#2 & set#3


Set #1, the "real" stereo, is it as sharp and easyily viewed as the
right lens pair and the left lens pair which have no magnification
error?

Since mounting is critical, it would help if someone experienced did it
:-).

All I'm suggesting is that it may be a simple "proof" test that the lens
matching is "useful" for those who refuse to rely on numbers.


> 
> Per Greg's suggestion, mount this pair in an Albion mount (I pick this thin
> aluminum mount as ideal for this test.  If you don't have one -- you only
> need one, send me a SASE and I will send you one!!!) Push the chips down
> to align the bottoms.  Look at the top. If the tops are not cut at the
> same line, then you have mismatched lenses.  It is simple.

I agree with that it is a simple test.  Thanks for the generous offer,
but I will scan :-).  I think that the postage might bankrupt you and I
could forget the original intent by the time they got here.  ( My record
for US/Canada first class mail is 47 days ! ).  I plan to findout the
extent to which a computer can produce quality anaglyphs as my first
project.  I'm including distortion removal etc. in that process.

BTW, I can't remeber who (because I lost the reference in my zeal to
cleanup my harddrive) posted another reference suggesting 0.5% is the
maximum tolerance maginification error for a 3d projector.

Regards,
John


--
John Ohrt,  Regina, SK, Canada
johrt@xxxxxxx


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