autofocus in canon cameras-objective evaluations?

[Jonathan Wienke]

I have a 10D and a 1D-MkII. Imagine the difference between an Indy car and a minivan.

[paullantz]

one of these days I will probably try out another camera

the 10d focus speed problem is worst in situations with a bird that is relatively patternless and very close but generally not flying very fast.

e.g. in this shot which is a 1/3 width size of an almost full frame shot

right overhead

[Jonathan Wienke]

Doing a totally objective head-to-head is difficult because there are so many variables involved. Lighting, the lens, and the subject matter all significantly affect AF speed and accuracy. In optimal conditions with full sun and contrasty subject matter, the 10D and the 1D-MkII are both fast. But in dim light with fairly monochrome subject matter, the difference becomes pretty noticeable. At some point the 10D AF will just give up but the 1D-MkII will still work.

[paullantz]

Right now I use a 10D. I am generally very happy with it except when it comes to auto-focus with moving objects, especially where the relative movement is fast(e.g. a bird flying overhead).
At some point, I probably should buy a better camera...
I am curious if other forum users are aware of any objective evaluation of the auto-focus systems in current canon cameras (eg. 20D or 1d mark ii).
I mostly use the 100-400 L lens, without IS for moving birds. I know that this is not the sharpest lens in the world at 400mm but it does produce some sharp shots of stationery objects which is why I am curious about auto-focus.

[Paul Sumi]

Not aware of any objective evaluations, but I second Jonathan's analogy.  The 1D Mk2 is wickedly fast.  I would suggest borrowing/renting the 20D or Mk2 to see which best fits your needs (and budget).

[pathfinder]

I think part of your difficulty is the lens you are using with the 10D.( This is not a snide comment at the 100-400 IS L - It is one of my most used lenses, but it CAN be soft if not used carefully - even on a 1DMkll!) I used a 10D until I replaced it recently with a 20D.  I also own a 1DMkll, so I am familiar with all three Canon bodies.
  But the autofocus in the 10D will not perform at its best with an f5.6 maximum aperature, which is what the 100-400 f4.0-f5.6 IS L  is when zoomed all the way out.  A faster maximum aperature lens - f4.0 or f2.8 will help the 10D quite a bit, particularly if the light level is low.  

    This is a nice way of saying the 10D works better with nice prime L telephotos like the 300 f2.8 or the 400 f4.0 DO.  I have many lovely shots with the 100-400, but the 10D definitely will focus better with these faster primes.  Kind of makes sense - More light = better focusing!
  The other think that will help the 10D, is to use ONLY the center focal point.  I was never happy with the focusing  of the 10D until I  turned all the other focus points off. And you must shoot in the Creative Zone ( as Canon calls it ) not the Basic zone to do this.
   The 10D can take lovely pictures with the 100-400, but the 20D and the 1DMkll are faster in dim light.  But I have shot images in darkness that the 1DMkll could not autofocus in either - but that was with a tripod anda 24-70 L, not a telephoto.  

    SO the failure is not in the tools per se, but just expecting too much out of them !?