Want 400mm reach (FF) - 70-200 2.8 IS II + 2x III or 400 5.6L?

[neuroanatomist]

I've got the 7D, but to me it was so far off I didn't think the micro-adjustment would work. I also called CPS and the guy wasn't sure if the microdjustment would remember the lens/extender combo as it's own lens, or if it would remember it as the 70-200 II. I'd say 15 feet off at 90 to 100 feet.

AFMA values are stored separately for each lens + TC combo (and with newer cameras, by serial number as well, so you can have more than one of each lens or TC type). 

Each unit of AFMA is 1/8 the depth of focus, so with 20 units you can correct for 2.5x the depth of focus - that's a fair bit of latitude in the correction.

[vargyropoulos]

I was in the same boat as you until recently. I chose the 400mmf/5.6L lens and I could not be any happier (well maybe if I had the 600f4L.....). Granted, the 100-400 has IS but in testing the lenses head to head at the store I found that for any shots faster than 1/500sec, the 400mm prime was sharper than the 100-400.

after I bought it, I have shot it at 1/250 sec handheld with acceptable results. if I'm shooting still objects... I put it on a tripod anyway.

[Rockets95]

I've got the 7D, but to me it was so far off I didn't think the micro-adjustment would work. I also called CPS and the guy wasn't sure if the microdjustment would remember the lens/extender combo as it's own lens, or if it would remember it as the 70-200 II. I'd say 15 feet off at 90 to 100 feet.

AFMA values are stored separately for each lens + TC combo (and with newer cameras, by serial number as well, so you can have more than one of each lens or TC type). 

Each unit of AFMA is 1/8 the depth of focus, so with 20 units you can correct for 2.5x the depth of focus - that's a fair bit of latitude in the correction.

Neuro, I just spoke to Phil at Norman Camera and he verified my field test results with the front focusing issue, and also confirmed your info that the 7D with microadjustments for the combo will be treated as it's own separate lens. He's sending me another 2X III, so it must have been beyond what would be considered normal tolerances.

[K-amps]

Folks,
Thanks to all for your advice and opinions - it has helped me make a simple (mostly financial) decision - I'll add the Extender EF 2x III to my collection.

An additional benefit will be that I will be able to take the 70-200 lens and get into a venue (I live in Sydney, Australia) for Twenty20 cricket whilst keeping the 2xIII in my pocket - and not get hassled for a too-large lens.

I already have a Manfrotto CF monopod and head - hopefully the gate people won't give me grief about that (no problems last time - I extended it and used it as a walking-stick on the way in!)

Cheers

I would have done the same! 

Having said that, a used 7D can be had for $800-900 these days. If you use that with your 280mm, you get about 450mm and an extra body