Canon 300mm f/4 with canon 1.4 or 2X extender (mk3 vs mk2) or 100-400mm

Started Jul 2, 2013 | Questions thread
Steve Balcombe
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Re: Canon 300mm f/4 with canon 1.4 or 2X extender (mk3 vs mk2) or 100-400mm
In reply to DGways, Jul 2, 2013

DGways wrote:

Thanks, can anyone vouch for the autofocus speed of the 300 f/4 with the 1.4x teleconverter (mk2 or mk3 specifically)?

I used mine with the Kenko Pro 300 DG 1.4x, which is for all practical purposes a clone of the Canon MkII. Autofocus speed is very acceptable.

As I understand it, the additional electronics in the MkIII only work with the MkII big whites, so on the 300/4L IS the MkIII AF performance should be the same as the MkII.

also, does anybody know if autofocus will work with a 300 f/4 lens, a 550d body, and a mk.3 2x teleconverter?

That makes an f/8 combination, so the answer is no.

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