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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Canon EXtender 2x III - Autofocus capability? (1 Viewer)

mikenott said:
Does anyone have any idea whether the new 2x III will autofocus with (say) a 500 f4 IS? It won't with the 2x II but this link ( http://www.usa.canon.com/dlc/controller?act=GetArticleAct&articleID=3508 ) is a bit ambiguous. It seems that the 5.6 limit still applies .... or does it?

Michael.
Click to expand...

It depends on the body, if 1D then OK at f8, if xxD or 7D then the f5.6 restriction still applies I believe. The body drives it not the lens and tc combination. Stand to be corrected if I am wrong.

Phil
 
Well, that makes sense and explains this note on the link page I gave:

"With most EOS cameras, the maximum aperture of the compatible EF lens/EF extender combination must be f/5.6 or larger to support autofocus. With EOS-1 class digital SLRs, autofocus with the center focusing point is supported for compatible EF lens/EF extender combinations with maximum apertures of f/8 or larger".

So, it does beg the additional question "Why is the new 2x III double the price of the 2x II (or are pre-release prices just a vague approximation?)?

Michael.
 
mikenott said:
Well, that makes sense and explains this note on the link page I gave:

"With most EOS cameras, the maximum aperture of the compatible EF lens/EF extender combination must be f/5.6 or larger to support autofocus. With EOS-1 class digital SLRs, autofocus with the center focusing point is supported for compatible EF lens/EF extender combinations with maximum apertures of f/8 or larger".

So, it does beg the additional question "Why is the new 2x III double the price of the 2x II (or are pre-release prices just a vague approximation?)?

Michael.
Click to expand...

Better optics, af capability and build I guess. Will be buying one when price drops a bit and getting rid of my mkII. Looks like optimum performance is on the new lenses according to the article but they would say that wouldn't they! Have to say that on my 1D, 300 f2.8 and MkII combination it all works great.
Maybe will try it on a 7D which will still af.


Phil

Phil
 
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