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Old Mar 31, 2005, 3:21 PM   #1
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I've seen conflicting information on this:

With a CanonExtender EF 1.4x IIdoes the 20D's Auto Focus work with the 70-200mm F4 L and/or the Canon 400m F5.6 L?


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Old Mar 31, 2005, 4:44 PM   #2
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EOS 20D does not focus past F5.6 so

yes, 70-200mm F4 L +1.4 tc = F5.6
no, Canon 400m F5.6 L +1.4 tc = F8.


The 1.4 tc adds 1 stop of light loss to each lens.

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Old Apr 1, 2005, 12:17 PM   #3
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Canons compatibility chart shows both lens will work. f4=5.6, f5.6=8.
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Old Apr 1, 2005, 1:34 PM   #4
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Yes, both lenses will work with the TC when used on a 1D pro series camera which can autofocus lower that the non pro bodies.The 20D autofocus capability does not work well past F5.6.

It depends on which camera you are trying to use it with. This thread is asking specifically for use with the 20D. So for that F8 combination it means switching to manual focusing, you can still take pictures but no autofocus function.

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Old Apr 1, 2005, 6:48 PM   #5
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Ok it makes sense to me now.

Thanks.

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