P3D projection problems

[Richard Twichell <rmt@xxxxxxxxxxxxxxx>]

regarding ghosting in one eye... I have found that some of the "better" 
glasses - the ones in hard plastic black frames - have one or both of 
the polarizers misaligned, making it impossible to get adequate 
extinction from both images simultaneously.  Quick test:  project the 
questionable side alone, and see if tilting your head from the level 
position improves extinction  (tilt both ways, and close the other eye!)
regarding screens - my recollection is that Ferwerda reported on 
extensive tests of various screens and the degree of depolarization 
varies widely.  How to avoid buying a half dozen "bad silver screens":  
Buy one at a time!

Dick Twichell



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