Canon Extender EF 1.4X II Teleconverter and autofocus

[siberia1997]

Can I get some straight scoop on autofocus as it relates to Canon's 1.4X II TC? I have a 20D, and I'd like to get the TC for use with my Canon 70-200 f/2.8. Will I have autofocus at all f-stops, even as wide as f/2.8? I've read that one has to stop down to f/5.6 with the TC in order to make autofocus work with the lens, unless you put tape on the three most left pins of the TC (when looking from the lens connection side).

Is this true? Any risks?

Thanks.

[mjs1973]

Check out this thread. Lots of good info and sample pics from this lens TC combo.

[siberia1997]

No info. within the thread on my question.

Thanks, anyway.

Anybody else?

[mjs1973]

Opps, I was thinking that Loupey was talking about the 1.4 TC but now I see he's using the 2.0. Smartwambat does mention using the 1.4 TC in that post and had no probelm with the AF or IS. I have never heard anything about having to cover any of the contacts to get a lens+TC combo to work.

As for stopping down to f/5.6 to get the AF to work goes against everything I know about AF. The more light you have, the faster the AF should work and I would think that stopping down to f/5.6 would hinder the AF function, not help it.

There are some reviews for this TC on this site, and one of them states "AF speed is undiminished".

I'm sure if there was any of the AF or tape the contacts issues with this product, it would show up in the reviews. Be sure to check ou the Canon web site to make sure what lenses this TC is compatible with.

Reviews: http://www.photographyreview.com/cat...1_3132crx.aspx

[siberia1997]

Thanks for your help.