Re: Ghosting due to high-contrast subjects vs depolarization

[P3D Bob Wier <wier@xxxxxxxxxxxxxxx>]

|the x-ray shots.  He was convinced that the problem was that the 
|transparencies were produced using a film base that de-polarizes the light.  
|He said that it is a common problem when projecting such slides.  His 

I might note that in another mailing list that I'm on (photography/genealogy)
that a discussion is proceeding at this time about the use of crossed
polarizers to determine the type of film base used on a given image. It turns
out that different bases do indeed have characteristic polarization effects.
Another way to determine the base type is via burning - although this isn't
recommended for archival/historical images :-)

THANKS

   ====== wier@xxxxxxxxxxxxxxx ======
  4:17 PM Saturday, July 26, 1997
   keeper of the Photo-3d, Overland-Trails, LDS State
    Research Outline Guides and other stuff
     (currently in Ouray, Colorado)



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