On Mon, 5 Aug 2002 21:56:16 -0700, "KCamera" wrote:

>Last week I was using my 20-40 Tamron with my Canon A2 and was taking
>several landscape pictures. I use a B+W 77mm Circular Slim Polarizer with
>this lens. I was totally suprised when I was composing an early morning
>picture over a river and a major portion of my viewfinder darkened and a
>dark smear appeared in the upper part of the viewfinder. Removing the
>polarizer removed the abberation. I cleaned the polarizer and the lens but
>to no avail, the distortion returned whenever the camera was directed at a
>bright or reflective surface. Let me be clear here,this is not flare. When
>the lens was released and slowly turned the image in the viewfinder did not
>turn. I tried the filter on a 300L and no problem. I put the 20-40 and the
>polarizer on my back- up body, a Canon Rebel and a different pattern of
>abberation appeared in the viewfinder. I took pictures anyways with the A2
>and the distortion does not appear in the final product. The pictures are
>normal in every way. The A2 was given a check-up by Canon in the fall and
>the Rebel sees little action. The 20-40 is relatively new,as is the
>polarizer. My equipment is in pristine condition and is always stored in
>optimum conditions. I should also explain that the distortion in the
>viewfinder remains in the same pattern even when the camera is pointed at a
>different scene, low light or otherwise. After the camera has been turned
>off ror a while the problem seems to disappear. If anyone has had this
>experience or has a plausible explanation I would certainly appreciate
>hearing from you.----Thanks

You may be viewing stress patterns in the plastic VF
materials - polarized light is useful for this (though
I would not expect it with a circular type...). BTW, I
would expect what you saw in the sky area shot with
a polarizer on a wide-angle lens - the polarization of
the skylight should be uneven with wide coverage...