1st-Gen 100-400L + 2x Extender = ???

[Joe Copalman]

I just bought Jeff's old 100-400 and have noticed the 100mm hit from the 150-500 I was using before, even if the shot-to-shot consistency is better with this lens. 

Has anyone used a 2x extender on the old 100-400 before?  If so, what was your experience?  I've heard a few different things like you have to use manual focus depending on which kind of body you're using, etc, and that it drops your max aperture, but I'd like to hear some of this from shooters I know and trust.  Any details on experience you've had would be greatly appreciated.  Thanks!

[Jay Beckman]

The IQ hit is enormous and you lose the ability to auto focus...

Not a recommended pairing based on my experiences.

The two-stop loss in light locks you at a max aperture of f/11 on the long end

In general use (aside from the teleconverter question), try to stay at a max of f/8 and see if the quality improves a bit over f/5.6 on the long end.  Take the ISO hit if you have to as a little NR in post will clean things up.

[Joe Copalman]

Good intel, thanks.  And this would apply for the version III copies of the extenders? 

[Jay Beckman]

My experience is the the MkII versions, but I don't recall anyone ever saying that there was a marked improvement with the MkIII versions...

[Anna M. Wood]

Same things apply for the Mk III extender that Jay sees with the Mark II.

If you want we can meet up out at Sky Harbor and I will let you try out my 1.4X Mk III and 2X Mk III.  Both will be manual focus only.

You would need a 100-400 Mk II / 1.4X Mk III combo with a 7D Mk II, 5D Mk III or 1DX to get a center point auto-focus at the f8 aperture.

Last weekend at Coolidge I shot with my 7D2 and 100-400 Mk II / 1.4X Mk III combo.  The IQ was better then expected.  The following two images were with that setup.  Good lighting, I am sure, is your friend here.