P3D Re: my 2 cents worth on adjusting projectors

[roberts@xxxxxxxxxxxxxxxxx (John W Roberts)]

>Date: Sat, 27 Jun 1998 05:35:25 -0600
>From: "Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
>Subject: P3D Re: my 2 cents worth on adjusting projectors

>I had no idea that this issue was so important to have members dropping
>off PSSP (Potomac Stereo Society of Stereo Photographers).  Because in 
>my 4 years in Detroit and one year in Cleveland, it has not been an issue.
>So maybe perhaps it is an issue only the clubs that adjust the projector
>between slides?  (just a thought...)

And only in countries with freedom of the press will you find newspaper
articles discussing freedom of the press. In itself, that's not a valid
reason to restrict it.

>So you cannot eliminate ghosting by mounting IF the slide will be projected
>in screens of very different sizes.  But if you mount the sunset at
>window level, it will be much better than if you mount it at infinity,
>no matter what size of screen you are using.

Wait - I must have missed a message in that subthread. Are you saying to
set the stereo window to infinity? I've done that occasionally for various
reasons, but I thought the "window-lovers" considered that to be vilest heresy.

>>the need to make minor adjustments during projection is
>>almost unavoidable.  The most important word in that sentence is "MINOR". 

>As I have said before, MINOR = NOT NECESSARY.

What constitutes "minor" and what is "necessary" are judgement calls -
in other words *opinions*. Throughout this discussion, your choice of words
has given every impression that you're trying to pass these opinions off as
*facts*. (Sort of the "Carthage must be destroyed" method of debate.)

For my part, I believe there are cases in which a "minor" adjustment,
while not necessary to see stereo, can still be justified on the grounds
that the adjusted image is so much more enjoyable (though of course it's
preferable that this adjustment be performed during mounting rather than
during projection).

Part of the difference in OPINION may be personal perspective. I've still only
been to a few stereo club meetings, and much of my reason for attending was to
see the best of what the projection format is capable of, not so much to see 
who can do the best job of mounting, or how much of a misalignment I can grit
my teeth at and still manage to enjoy.

Perhaps I'm more sensitive to alignment issues because I've seen very few
projected stereo slides. The long-time projection viewers who can swivel
their eyes independently like a chameleon may be able to compensate for
alignment errors more easily, and thus be more tolerant. Beginners may
not consciously notice an alignment error, but may notice that they have
a headache after the club meeting, and over time this may discourage their
repeated attendance. So perhaps I'm just at that awkward stage where I'm
sensitive to alignment problems, but not yet able to check the weather 
overhead and tie my shoelaces at the same time.

I noticed that you specifically commented on the question of whether I had done
vertical adjustment or horizontal adjustment, then basically indicated that it
didn't matter. Why make a point of bringing the question up if it doesn't 
matter which? Could it be that somewhere deep in the Themelis subconscious
is the notion that just possibly vertical alignment does matter more than
horizontal, and that vertical adjustment might be a tiny bit more justifiable
than horizontal? That would echo my views, except that I'm not afraid to come
out and admit it. I find that I have the most objection to vertical alignment
errors, and am relatively tolerant of horizontal mounting (unless something
in the field of view is set way beyond infinity).

>All I care about is for people to have a good time viewing 3d projection.

That's a good and worthy cause, and I applaud your efforts.

>Adjusting the projector between slides will give people (especially 
>newcomers) a headache and turn them off 3d.  That's the only danger.
>Other than that, I "don't give a damn" what you people do in your
>meetings.

I can give my perspective as a long-time stereo viewer, but new projected
slide viewer. Upon first seeing slides adjusted, my instantaneous reaction
was "Oh no - I've looked at a few projected slides, and now the visual
center of my brain is flipping out!". Pretty quickly, I realized that this
only happened when adjustment of the slides was being discussed. I *do*
find it annoying to watch the slides during adjustment, if I'm not one of
the ones doing the adjusting - so I generally look away during the
adjustment process.

[I think we can pretty much guess what your response to the previous
paragraph is going to be, and also my response to your response, so why
don't we "take it as read", and save bandwidth? :-) ]
John R


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