----- Original Message -----
From: Mortimer Snerd <[EMAIL PROTECTED]>
> I kept the focus sensor "bullseyed" on a high-contrast
> item in the center of the frame, like a grille.
> Everything looked fine thorugh the finder, but when I
> got the pictures back, most of the polarizer pictures
> had focus blur. ..................
> I've used the same 77mm Tiffen circular polarizer on
> my Sigma 135-400, and autofocus gets really marginal
> with the polarizer on, it hunts a lot and can't seem
> to acquire and track a target in AI servo mode. My
> 100-300 f4.5-5.6 USM has similar problems with a
> polarizer installed. Focus is noticeably more
> ponderous with the polarizer attached, and it becomes
> useless for action shots in AI servo, you have to
> anticipate where things are going to be an focus
> manually.
Thanks for coming back to me on this Mat. I appreciate you outlining your
experience and it certainly sounds like the CP has an effect on AF
performance. If I end up with the filter I will let you know how it effects
my equipment after the next track day. The 1v and 300/2.8 may react
differently.
Regards, Tim
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