Answers to Gary's accumulated questions

[P3D Dr. George A. Themelis <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

>Since I'm viewing the slides in my Realist Red Dot, should I observe 
>the spacings shown for the slide format, or stick to the standard 
>realist setting? 

It does not make much difference.  If you use Realist mounts, follow
the realist setting.  If you use 7p or wider, follow the other.
But, I don't even use a mounting gauge, so, what do I know...?

>I always set the infinity point to the mounting gauge and let
>the close objects fall where they may.  At least people won't have 
>to _diverge_their eyes to fuse projected images. Besides, it really 
>doesn't bother me all that much if something comes through the window 
>a bit -- even if part of it intersects the frame. 
>Is mounting this way 3D heresy?

No, this is the "mathematically" correct way to do it.  However, I do
not do it that way because the mathematically correct way is not the 
esthetically best, IMO.  And my problem is not so much things that stick
in front of the window and mess up the edges, but the opposite, i.e.,
nearest things being too far back and getting lost far back from
the window (It is the lack of depth "Hi Larry!", i.e. deviation, that 
creates this problem, BTW.)  

So, how do I do it?  I mount the nearest object by window level
(slightly behind or through the window, if possible and desirable)
and let the infinity fall wherever it may.  One advantage of my
mounting system:  I do not need a mounting gauge!!! Yeah!!!

Because I do not over-do-it in depth, the infinity is always below 
the maximum allowable separation.  The audience will slightly converge
their eyes even at infinity.  They should not need to diverge 
(assuming 70x70 projection, etc.) if you err in the conservative
side when you record the picture.  DrT's reduced stereo depth 
philosophy:  The less the merrier, as long as it is still 3D. :-)

>I've been wondering. On the one hand I see Sam's 3D Hacker web page, 
>where I get the impression that as soon as he finds two cameras of 
>the same kind, he joins them and creates yet another wonderful 3D 
>camera. 

Yes, Sam has the Golden Stereo Touch.

>On the other hand, there are the discussions here that lead me to 
>believe that the lenses must match exactly, or 3D isn't possible. 

But, you did not ask DrT!  All this "nonsense" about matching to
0.001% (is that the definition of _exactly_?) can be safely discarded 
as... well, nonsense!  Sam is a practical man and knows that
"perfection" is a very time-consuming and expensive affair.  Why be
"perfect" when "good" is good enough??? :-)

>I'm wondering which impression is the most accurate, at least in 
>practical terms. I've got two Pentax KXs that I'd like to use for 3D, 
>but I doubt if I can find a merchant that will let me "try 
>out" half a dozen lenses until I can find two that match perfectly. 
>If, by the luck of the draw, I get two lenses that are _not_ matched, 
>will I be able to use them?

Define "_not_ matched".  Usually tolerances of reputable SLR makers
are tight enough to guarantee an "OK" match.  If the lenses are far
off for _your_ standards then return them, or get a third, keep the
two that match the best, and return the third.

John W. Roberts and myself have picked lenses for our X-700 systems
randomly and are both happy.  Most probably you will be happy too.  Some 
pairs do not match _perfectly_ but I have declared that I am not a 
perfectionist, and no one seems to have any problems or complaining 
about my slides (except for a perfectionist or two here and there).

HAVE FAITH AND STEREO PHOTOGRAPHY WILL REWARD YOU!!!  :-)

I'll let now the professional stereo photographers who populate this
list explain the faults of my thinking and will go and have another 
beer and shoot a few more pictures! :-)

Good luck in your twin SLR project and slide mounting!!!  Remember,
focus on the big picture and let the details fall where ever they 
may (same as mounting by the window)!

-- George Themelis


------------------------------