Extender compatibility with EOS 7D/6D and EF 100-400mm lens

[Lonestar_North]

I use a 7D and a 6D. I would like to buying a Canon EF 100-400mm f/4.5-5.6L IS II USM. Would my Canon 1.4X II and 2.0X II allow for auto focus with this camera combo? 

[PLee · Accepted solution]

Neither the original EOS 6D, or original EOS 7D will support autofocus through the viewfinder with the EF 100-400mm f/4.5-5.6L IS II USM and either the 1.4x III or 2.0 III extenders on the long side of this lens as the respective apertures would drop to f/8 and f/11 a little past 300mm for this combination. Live View autofocus on both cameras would be slow and flaky at best, especially at f/11, and not really useful for anything moving.

[MikeSowsun]

If you switch to Liveview, the Contrast Detection Autofocus will work on both the 6D and 7D.

[avarela123]

Bingo! I just picked up a used 2x iii with the 70-200mm f/4L IS.  I could only get it to focus while in live view and I thought that either the camera or the lens were defective.  I was ready to return it until I saw your post that confirms it's functioning correctly.  Thanks!

[ebiggs1]

" Would my Canon 1.4X II and 2.0X II allow for auto focus with this camera combo?"

I would never use the 2x tel-con on that or any other lens for that matter. Performance is going to be slow at best.

[Waddizzle]

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@Lonestar_Northwrote:

I use a 7D and a 6D. I would like to buying a Canon EF 100-400mm f/4.5-5.6L IS II USM. Would my Canon 1.4X II and 2.0X II allow for auto focus with this camera combo? 

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Not sure if the Version II models even know that lens exists. If anything, I believe you would need a 1.4x III with that newer lens, and forget using a 2.0x extender. In fact, forget using an extender with that lens on either of those bodies. You will lose AF.

[Lonestar_North]

Thanks all.  I have a much better understanding.  To buy the lens I want to use I have upgtrade my camera.  Spend $1000 before I can spend $1000.  Gosh I love thios hobby

[ebiggs1]

"Gosh I love thios hobby"

And, it never ends!  

[RobertTheFat]

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@Lonestar_Northwrote:

Thanks all.  I have a much better understanding.  To buy the lens I want to use I have upgtrade my camera.  Spend $1000 before I can spend $1000.  Gosh I love this hobby

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You've got to keep it in perspective. For the same level of involvement, photography is probably cheaper than either skiing or golf, almost certainly cheaper than flying or collecting vintage cars, and vastly cheaper than maintaining a large sailboat.

BTW, that argument can be used on one's wife, who often serves as a brake on squandering the family fortune. But I can tell you from experience that the best way to handle that issue is to get her involved in photography too - especially if she happens to have a talent for it.