Re: [photo-3d] Re: [3Dsalon] Misalignments & stereo projection

[Project3D@xxxxxxx]

In a message dated 31/03/01 18:45:11 GMT Daylight Time, drt-3d@xxxxxxx writes:

<< George Themelis quoted Steve Dudley with::
 
 >At the Chicago Stereo Camera Club competition nights,
 >there were three remote cables extending in front of the
 >projector for the 3 adujstments (focus, horizontal, vertical).
 >It was quite a spectacle to have four people (projectionist
 >was a seperate job) working on the projection the first time 
 >or two I witnessed it, but it worked great.  
 
And then says:

<< For you maybe... When I attended my first (and only) CSCC
 meeting in 1989, even though I was a beginner in stereo, I 
 already knew that something was wrong with this picture... 
 My eyes were telling me that this was wrong.  Especially 
 the horizontal adjustment.  I was puzzled and unsure why
 this was changed.  It was changed to minimize ghosting.
 I continue to think that this is a very-very BAD idea. 
 I also continue to think that changing the vertical
 alignment to correct vertical mounting errors is also
 a bad idea.>>

I'm with George on this to a large extent. Certainly, there should be no need 
for constant horizontal adjustment. Vertical adjustment is a different 
question. 

In a perfect world there would be no vertical misalignment in the slide 
mounting. But the only really foolproof way to ensure this is for all the 
authors to check their slides in a projector. Of the same model as will be 
used for the show. This last because different projectors support the slides 
at different points, and if the slide doesn't sit straight in the projector 
gate, there will be a vertical offset on the screen. This is especially 
likely with foil/card combinations. A slick projectionist can alleviate the 
pain of the audience by rapidly setting the vertical alignment.
 
<< To go back to Steve's previous posting, when I left the
 St. Charles 1997 PSA convention, I had mixed feelings 
 about stereo projection.  Just like Steve, I felt that the
 TDC projector has been a reliable workhorse for 50 years
 and the new "fancy" projectors cannot match this reliability.
 "Life was simple and BETTER" back then, when the TDC was
 used, was my thought.  However, there is a limit with
 the TDC. This limit is the 70x70 in. screen.  Unless
 "beefed up", this projector cannot be used for large
 audiences (but it is still perfectly adequate for small 
 audiences and home use). This summer I attended the NYSS 
 meeting in July and I must admit that their dim TDC on 
 the large screen was a disservice to stereo projection, 
 especially compared to the Ektagraphic 2x2 projection that 
 followed.>>

I routinely project onto a 7 x 10 foot screen using a Dual Hawk projector 
whose light output is quite sufficient - in fact, we've just upgraded our 2 x 
50 x 50 equipment to catch up!
 
<< We need a better (more powerful, reliable, simple and
 easy to operate) stereo projector.  I believe the RBT
 projector meets these requirements, except for the
 glass mount question and the high price.>>

I'm sure George is right here, too! I firmly believe in the RBT projector (I 
own four! :-)  )but it does have its limitations. I've even had the 
occasional RBT mounted slide fail to drop - in a projector that has recently 
been overhauled and brought up to current spec by Franz Almendinger of RBT. 

However, the light output is great! And the autofocus is wonderful! I prefer 
to use the RBT for everything - by hand feeding it. I hope the next RBT model 
will make it easier to hand feed the projector so everonewill do it. And I 
wish the "Slide shaft" (the channel that the slides drop down) was just a 
touch wider - I often find myself fighting to get badly aligned foil/card 
combinations out of the projector... 
 
<<On a personal level, with my RBT projector I have now 
 progressed from the 5 people projection team to the 0 
 people projection team.  I plan to test drive the RBT
 in our club competition this coming Tuesday on a "mix
 bag" of slides.  One of the judges can hold the remote 
 to advance and focus, if needed.  Nothing else is 
 changed.  No projectionist is needed.  From what I have
 seen so far, I am confident that everything will go
 well.>>

This really only works well with consistently mounted slides.

There is too much "play" in the vertical adjustment control on 
the projector to allow it to be changed during a shop.

Of course, this could be a blessing in disguise! If it means that 
judges mark down slides that are unviewable without projector 
adjustment (which, of course merely reduces the pain - it doesn't
do anything to produce a clean "window"!) AND authors whose 
work has been marked down for this reason are given help - by 
force if necessary! - maybe we'll get equality between 41 x 101
mounts and 2 x 59 x 50!

Bob Aldridge
Stereoscopic Society Projectionist
 
 George Themelis >>

 

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