P3D my 2 cents worth on adjusting projectors

[Project3D@xxxxxxx]

On Sat, 27 Jun 1998 11:36 Dr. George A. Themelis wrote:

<<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...)>>

I'm beginning to wonder whether the "should we adjust the projector" argument
arises because some people adjust the projector without the necessary finesse!
(And often that finesse means no adjustment AT ALL!). I think there is a
middle ground to go down. 

In an AV show from one author, there is no reason to adjust the projector.
This is why I can project Pat Whitehouse's "Tribute To Handel" with some
slides only on the screen for 6 or 7 seconds. It's a full AV dissolve show
projected (for choice) with the Dual Hawk projector. Fully manual. Try
adjusting verticals and horizontals in that - the next slide would be on
before jou'd started the adjustment!

BUT with mixed slides from a variety of authors with a variety of skills,
there are times when judicial adjustment can be beneficial - and this is where
the skill of the projectionist comes in! I'm not naming names, but I know we
have a couple of slightly clumsy projectionists over this side of the pond...

<< >" Of course, this means
>that you CANNOT mount to eliminate ghosting, because the mounting would
>have to be different for different screen sizes..."
>Bob Aldridge
   
>THANK YOU!  THANK YOU!

I think you are getting too excited here.  What Bob is saying is correct.
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.>>

Agreed, but it won't look truly "right". One of my specialities is "available
light" photography. (I remember teaching a couple of White House photographers
some tricks in Washington back in 1969 - no trouble with tripods, then!!!) But
I have stopped trying to project some of my favourite floodlit building
shots... With a range of distances (which you don't always get in a sunset)
all trying to produce ghost images, it's just too distracting. Oh, and to
digress into another previous post, increasing the ambient light in the room
INCREASES the ghosting! Projection rooms that are not properly blacked out are
the enemies of projected 3-D.

<<Let's move to the next question:  Does ghosting need to be eliminated
by adjusting the projector?  I don't know what Bob says about this, but I
say, NO.  I believe that you should not adjust the projector to eliminate
ghosting.  If the nature of the image is such that it displays severe and
distracting ghosting, it should not be projected.>>

I agree totally. It's a pity that people (including judges of competitions
that are pre-judged) aren't more selective. I've been involved with enough
judging sessions to know that the judging is far from scientific. As a
projectionist, I tend to mark down for technical faults. Sadly, very many
people - including people that have been making stereo images for YEARS cannot
see bad mounting! Others have their own bees in their bonnets - I once heard a
proponent of the "mount everything to infinity" school remark that he hadn't
marked down the worst mounting errors, because everything was mounted wrongly
anyway!!!

<<Have you heard the expression: "This slide does not project well?", or
"this slide looks better in a viewer than in projection?"  So we are
accepting the fact that there are slides that don't look very good in
projection.  In the list of reasons for slides not to project well ("too
dark" is one) add "severe ghosting" and we are done.>>

And this is where a majority of stereo photographers are at a disadvantage. I
as a projectionist of many years standing am very fortunate in having a number
of projectors available for checking slide mounting and ghosting. But it
wasn't until I bought my first Hawk projector 20 years ago that I really made
progress in mounting - and SEEING what a well mounted slide looked like!

<<>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.>>

But major adjustments may be needed where the chips are not at the same height
- and the judges haven't thrown it out! If it's not pre-judged then the author
may not know what to look for, and should be gently led in the right
direction. This can be explained just as well with the projector adjusted so
the homologues are level - the apertures will not be, will probably ghost, and
will certainly float. Of course this should only apply to sessions where
inexperienced workers are having their slides projected for feedback. It's
important that they have the opportunity to learn.

Now, AV shows should, by definition, be from workers who have mastered the art
of mounting so that no adjustment is needed. If they don't know how to mount
correctly, then they are trying to run before they can walk.

<<>I know that this may be far from the last word on this, but I think IN MY
>OPINION AND LETS NOT GET ANY FLAME WARS GOING HERE its time for the Mounting
>Nazis to calm down, chill out, get a life, and learn to live and let live.

Do you count yourself in the "Mounting Nazis" group?  I think you should 
because you are expressing a very strong opinion here.>>

Well, once again, I'm lucky because I learnt to mount properly. But it's a bit
like learning Egyptian Hieroglyphs. Everyone comes up against a brick wall
that suddenly falls down when they "click"! Until people learn what a well
mounted slide looks like, they won't be able to do it themselves. And it's one
of those insidious little things. Because it just looks "right" it takes some
skill to be able to detect it!!!

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

BUT leaving a slide with a vertical disparity on the screen will also give
them a headache. So we have to compromise. Sadly, watching a good
projectionist at work makes people think that it's easy! Nothing could be
further from the truth - it takes great concentration and a fine touch on the
controls. Equally sadly, there are a number of bad projectionists around. So I
too care about people having a good time viewing 3-D projection, and some
adjustment may be necessary. It's judging when adjustment is needed that is
the problem. I try not to make any adjustments, but it all depends.....

<<Cheers! -- George Themelis>>

And let's all lighten up!

Bob Aldridge
Stereoscopic Society Projectionist


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End of PHOTO-3D Digest 2814
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