Mike,
As I understand it, polarizers must be made of plastic. For whatever
reason, glass can't be polarized. Thus, al polarizers are a sandwich, to
protect the plastic. The ultra expensive german ones as especially sealed.
Bill Pearce
----- Original Message -----
From: <usher99@xxxxxxx>
To: <olympus@xxxxxxxxxx>
Sent: Sunday, October 19, 2008 9:52 PM
Subject: [OM] Pol question
>
> Finally able to find a rear 43mm pol for the Tamron 400/4. (10 buck
> snipe) It is a single piece of glass???? Every other pol, linear or
> otherwise, always had two. Must be a good reason to add the extra
> glass. I do have some pol film to put on the T28 or T32 for cross pol
> purposes but perhaps that is a suboptimal way to construct them. I
> could see that perhaps a quarter wave retarder might be in the second
> glass for a circular flavor but it struck me as very odd construction.
> It is a bit of a pain to use with no way to rotate it externally unlike
> the newer Tam 300/2.8 AF. Any ideas of the advantages of the usual two
> glass construction?
>
> Thanks,
> Mike
>
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