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by WDCarrier on Tue Jun 13, 2017 5:01 pm
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WDCarrier
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In attaching my Canon 7D with the 1.4 II extender to my new Canon 100-400, the autofocus will not operate and shows manual (M) in the back screen.  However, with the extender and my 500 f4 the autofocus is operational.   If I replace the 7D with my Canon 7D II, autofocus works.  Thus I assume the issue is with the Canon 7D.  Does anyone know if I switch to a 1.4 III if this will solve the problem or do I just quit trying to use that combo with the 7D (the 7D autofocuses with the 100-400 without the extender)  
[font=Helvetica, sans-serif]“Our lives begin to end the day we become silent about things that matter.” MLK[/font]
 

by E.J. Peiker on Tue Jun 13, 2017 6:34 pm
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Non 1D series cameras before the 7D Mk II disabled AF when the aperture is f/8 or smaller.  Since the 100-400 + 1.4x is f/8, AF is disabled on these older cameras.  Your 500 is an f/4 lens so with the 1.4x it is f/5.6 which is still within the capability of the original 7D to autofocus.  There is nothing wrong with your gear - it is all working as intended.
 

by Craig Lipski on Wed Jun 14, 2017 8:35 am
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You might want to give this a shot; I didn't like it, but it's free and easily "reversible." (Also, I think I tried this w/ the 100-400 "classic" or the 400 5.6, not the new zoom.)

http://www.michaelfurtman.com/taping_the_pins.htm
Good light,
Craig
 

by WDCarrier on Thu Jun 15, 2017 9:49 pm
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Thanks for the info.  Since I need the autofocus speed for flying birds I'll just use the Mark II on the zoom and relegate the 7D to the 500 on perched birds.
[font=Helvetica, sans-serif]“Our lives begin to end the day we become silent about things that matter.” MLK[/font]
 

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