P3D Re: minimizing ghosts

[Project3D@xxxxxxx]

In a message dated 23/06/98 17:52:27 GMT, Dr. George A. Themelis wrote:

<<  
 >How do you mount slides to minimize ghosts?
 
 I thought I explained this... OK, here it is:  Mount the slides so that
 the object prone to ghosting sits at window level.  In the example of
 the sunset, the sun should be at window level.  Of course, this screws
 up the stereo window with infinity at window level, but, hey, that's
 the price you'll pay to eliminate ghosting and that's what happens
 if the projector is adjusted, instead of the slide.
 
 How do you put the sun (or any object) at window level?  By sliding
 the chips horizontally.  This is how you control the location of the
 window and that's what the mounting workshop will (hopefully) teach.
 
 -- George Themelis >>

Surely, in all of the above you mean "Screen" when you say "window"? In other
words, the homologues of the bright spot that is prone to ghost is co-incident
ON THE SCREEN. It is not necessary for the slide frames to be co-incident on
the screen. 

In fact, for anything over a 4 foot screen, the stereo window will be in fromt
of the screen unless the infinity points are separated by more than eye
separation. If your bright homologues are in the plane of the window, they
could have separation on the screen, and thus ghost. 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
Stereoscopic Society Projectionist 


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