P3D Using Polarizers

[Virtual Imaging <vidi@xxxxxxxxxxxxx>]

The discussion of polarizers has been appearing here regularly and I 
just thought I'd add my $.02 worth.

   In regard to the Round/circular polarizer question, the light you will want
to either enhance or eliminate in your images is linearly polarized.  So you
will be looking for linear polarizers, either circular or rectangular in shape.
"Circular polarizers" are nice to use in laser systems and for some CRT screen
anti-glare devices but I'm not aware of them being used in photography for the
reasons I believe you want.

   I'm surprised no one has mentioned that the deep deep blue skies one gets 
from using polarizers is not a guaranteed phenomenon.  The blue sky "emits"
linearly polarized light in what would best be described as a "cone" whose apex 
originates at the sun.  If you look at the sky with a polarizing filter (with the sun
at your back) you will only notice the effect of the polarizer in the sky that is to
your left, right and above.  You won't get much of anything in the direction the sun
is "pointing" or if you look in the direction of the sun.  But OH BOY what an effect 
it has in the right directions and when there are the right kind of clouds in the sky!

   Also, I haven't heard anyone mention the benefits of using a polarizer around
pavement (makes it jet black or shiny glare), or around glass on buildings and 
automobiles (takes the glare right off of the glass!), on water (you can often see
to the bottom of a body of water where you couldn't before because of the glare 
and sky), and lots and lots of other places.  Just look around.  To practice, take 
your polarized stereo glasses and look through one eyepiece while rotating them
about their axis and look around.  You'll really be entertained at what you will find.


John Vala


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