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[OM] Re: Polarizer crash course

Subject: [OM] Re: Polarizer crash course
From: miaim@xxxxxxxxxxxxxx
Date: Sun, 28 May 2000 09:48:46 -0400
>Date: Sun, 28 May 2000 00:51:22 +0000
>From: "John A. Lind" <jlind@xxxxxxxxxxx>
>Subject: Re: [OM] Re: Metal surfaces and polarizers
>
> A crash
>course on polarizers:
>(4)  If you look at a linear and circular side by side you will notice the
>linear has a single piece of glass which is mounted in the rotating ring.
>The circular has two.  One is mounted in the rotating ring and the other
>fixed in the part that screws into the lens ring.  On a circular, the part
>that rotates is a linear polarizer, just as with your linear one.  The
>fixed, second piece of glass behind it is a special filter that circularly
>polarizes the linearly polarized light that was admitted by the linear
>polarizer, effectively dispersing it into the same as linearly polarized in
>many directions.  Your eye doesn't care about the polarization.  That is
>why when the first one blocks the glare, it doesn't matter that the second
>one effectively disperses the polarization into many directions again.

John,
Thankyou very much for the crash course on polarizers. It helped and you
also answered my other q about whether it's necessary to use a circular
polarizer with an OM-4. Thankyou. 
Regarding comparison of circular and linear polarizers, I note that both my
Tiffen marked "circular polarizer" and my unmarked Vivitar (presumably
linear polarizer) have what appears to be a single piece of glass. At least
a bit of lint applied to the camera side rotates with the front side and
the apparent thicknesses would seem to indicate only one piece of glass. Is
the Tiffen marked wrong or do they use another process?

Mike Swaim

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