100-400 + 1.4TC

I believe that is true. I have 100-400 Mk2 but am waiting until I get 7D Mk2 before I get 1.4x for this very reason.
 
I think only the 7DII, 5DIII and 1D series cameras will autofocus with what is effectively an f/8 lens. So adding the 1.4x to 100-400mm is unlikely to autofocus on a 6D.
 
GeeJay57 said:
I think only the 7DII, 5DIII and 1D series cameras will autofocus with what is effectively an f/8 lens. So adding the 1.4x to 100-400mm is unlikely to autofocus on a 6D.
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Yeah thats what I read, thanks for the replies folks saved me £150.00 :-)
Thinking of saving for a 7D2 or possibly even trading my 6D in against one if I get hooked on this wildlife malarkey :-)
 
Jackwow said:
I believe.....
Click to expand...
GeeJay57 said:
I think.....
Click to expand...
I know. ;)

Fortunately you're both right, though the OP's understanding is a little awry.

Autofocus happens with the lens wide open, and in the Canon system the camera firmware usually requires the lens (or the lens plus extender) to report a wide-open aperture of f/5.6 or better. The only cameras which can do better than this are the 1D series, the 5D Mk III and the 7D Mk II which require the wide-open aperture to be f/8 or better.

So, take a 100-400mm f/4.5-5.6 lens, add a 1.4x extender, and you have a 140-560mm f/6.3-8 lens. Even at the shortest end of the zoom it is f/6.3 so it won't autofocus on your camera - this isn't just restricted to the long end of the zoom.

One way round this is to get a non-Canon teleconverter which doesn't report its presence to the camera. So the camera thinks the lens is still f/4.5-5.6 and it will *try* to autofocus.
 
StewartR said:
I know. ;)

Fortunately you're both right, though the OP's understanding is a little awry.

Autofocus happens with the lens wide open, and in the Canon system the camera firmware usually requires the lens (or the lens plus extender) to report a wide-open aperture of f/5.6 or better. The only cameras which can do better than this are the 1D series, the 5D Mk III and the 7D Mk II which require the wide-open aperture to be f/8 or better.

So, take a 100-400mm f/4.5-5.6 lens, add a 1.4x extender, and you have a 140-560mm f/6.3-8 lens. Even at the shortest end of the zoom it is f/6.3 so it won't autofocus on your camera - this isn't just restricted to the long end of the zoom.

One way round this is to get a non-Canon teleconverter which doesn't report its presence to the camera. So the camera thinks the lens is still f/4.5-5.6 and it will *try* to autofocus.
Click to expand...

Thanks for the detailed explanation :-)

I think I'll just "make do" with 400mm!!! I'm sure if things get serious and i need more there'll be options lol

Its pretty good at distance and IQ is amazing soi'll see how i get on :)

Thanks
 
You haven't mentioned which 100-400mm lens you have. IQ of the older lens is apparently ok but it's debatable whether the addition of a teleconverter would give you any benefit over cropping. The newer lens is reputed to be substantially better, and I've seen impressive results with the Canon 1.4x III extender on a 7D-II.
 
I've done fine with the 1.4 on my older 100-400 on my 5d mk3. You can also use live view for critical focus, which I do with the 2x on. No good for birds inflight but fine for static
 
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