2x extender + Cpl - autofocus ?

[skyking42]

Can anyone tell me if autofocus works with the following combination. Canon 70-200 f2.8, Canon 2x II extender and B+W Polarizing filter. I know that I would loose 2 stops for the 2x which makes the lens at 2.8 for a 5.6 exposure and the polarizer adds another 1.4 to 1.8 stops of loss which will make the lens wide open at maybe an f11 equivalent. Does autofocus still work ? I need the 2x range and will need the polarizing filter on some shots. I think it should work but if anyone knows for sure I would like to know. Thank for any info that you may be able to share.
John King

[tim]

On a 20D I think AF will try and work, but at such a low level of light might hunt. Maybe on a bright day it'll work ok. On a 1 series body it should work ok.

I'm sure I saw this question on FM earlier today.

[skyking42]

Yes you did see it. Only had one response so I thought I would increase the chances of someone having used the combo. And yes it is on a 20D. Thanks for your input Tim,
John King

[CyberDyneSystems]

Please take a look at the T-con sticky thread at the top of the forum..

the Polarizer will not effect AF.

[skyking42]

The polarizer was the reason for my question. I did not know how it would affect the combo. Thanks for the answer.