Using 7D / 100-400L and Extender 1.4

Started Oct 10, 2010 | Discussions thread
Jay S. Senior Member • Posts: 2,920
Re: Using 7D / 100-400L and Extender 1.4


There is nothing unique here. The 7D, like all the other xxD bodies will not autofocus with an aperture greater than f/5.6, which is what happens when you add any of the reporting 1.4 TCs to that lens (not just Canon). The exception in some cases are those TCs which do not have the reporting pins, or if you tape those three pins. The Mark III DS doens't have the f/5.6 restriction.

You can using the contrast focusing of LiveView. If you have enough contrast in the object it should work.

Jan Maguire wrote:

Hmmmmm... I have the Canon 100-400 and evidently the first version of Extender 1.4x (there's no II on it, and it's certainly not the III version just announced.

To the best of my ability, the 7D does not autofocus with my 1.4 extender. However, my friend has version II of the 1.4, same lens, and the higher end Mark III DS. He can autofocus with his 1.4x II on the 100-400.

I was shocked. I didn't have my 7D with me, or I would have just tried it. I am trying to verify ... is it the Extender 1.4II that makes the AF difference, or is it the higher end body than my 7D?

I did find a Canon note about the 100-400 with 1.4X II being able to use center point AF on older versions of the high-end camera. Doesn't list compatibility for 7D... anyone happen to have tried this combination?

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Jay S.
Fuji 7000 / Canon 20D / Canon 40D / Canon 7D

 Jay S.'s gear list:Jay S.'s gear list
Canon EOS 40D Canon EOS 5D Mark III Canon EOS 7D Mark II Canon EF 400mm f/5.6L USM Canon EF-S 17-85mm f/4-5.6 IS USM +7 more
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