Extender EF 2x III Compatibility with EF 400mm f/5.6 L USM Lens

[norrickb]

Will this extender match with my EF 400mm 1:5.6 L telephoto lens?  Will AF work?  I thought the 400 mm was pretty high end expensive when I bought it, but compared to the super telephotos available now I guess it was peanuts.

Maybe I need to upgrade the 400mm?

[normadel · Accepted solution]

Your lens is on Canon's list of  lenses compatible with the extender.

BUT*******Download the manual for the lens if you don't have it. It specifically states that autofocus is not possible. Only manual focus can be used with extenders. A possible reason is that the effective maximum aperture will be reduced to f/11, which doesn't give the AF system enough light to work with.

Check the manual for any lens you want to get. It will tell you if extenders can be used.

[shadowsports]

Greetings,

This information might help.  The EF 400mm f5.6 is supported

According to the manual, it will AF, but if trouble is encountered, then manual focus should be employed.  Ability will depend on shooting conditions and the lens.  Normadel is correct minimum aperture is f11 at 800mm

extender-ef-2x-iii-en.pdf (c-wss.com)

[normadel]

Shadowsports....

The manual says it WON'T autofocus. 

[shadowsports]

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@normadel wrote:

Shadowsports....

The manual says it WON'T autofocus. 

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Have I missed that?  Where does it say it won't autofocus.  Ah, In the lens manual, not the extenders manual.  This is misleading.  The extender manual does not say MF only.  The lens manual does.  Sorry I missed your point.

AF_MicroAdjustGuide_desktop.pdf (canon.com)

I think the list of cameras is out of date.  This pdf is from 2016

OK.  I found it buried in the 400mm f5.6 manual - The fine print  

[normadel]

I wouldn't expect the extender manual to deal with this. The extender doesn't know what lens is attached to it.

For a comparison, I checked the manual for a larger-aperture EF 400 f/2.8 L USM to see what it says: "AF is possible with an extender, BUT.......AF speed will become slower to retain proper control".  I'd think this is because of reduced light for the AF system.

So it goes to show users to look at the information Canon provides to see what works with what.

[Waddizzle]

It depends on the camera body.  It will not autofocus with any Canon DSLR.  It may autofocus with some the Canon MILC bodies, but with slightly degraded AF performance, usually a limited number of AF points clustered in the center like a DSLR.

[norrickb]

Thanks for your replies.  I'm convinced the extender isn't what I need.

[normadel]

I was torn between buying (used) an EF 70-200 L and a 70-300 L. The 70-200 could be used with an extender. The 70-300 could not. I reasoned that 200mm extended to 400 would be too much for me to hand-hold, involve carrying the extender around in case I wanted to use it. I'm glad I bought the 70-300. Keeps things simpler, and  I'm more steady at 300 than I would be at 400. 

I also read another thread pointing out that results using an extender versus cropping & enlarging  are about equal. And extenders are a thing that many get  because they sound like a neat idea, but they quickly get put in a drawer  and forgotten. More trouble than they are worth.

[norrickb]

Thanks again for your researched and thoughtful replies.  I'm convinced I'll just stick with the 400 mm until (if ever) I can afford a new generation super telephoto.