I have been shooting with my 100-400 L for quit some time, but recently decided to get the EF 1.4X II to extend my range, as I just bought a 40D to complement/replace my 20D.
I can't seem to get the autofocus to work, despite having played with apertures and all sort of other settings. I looked on the Web and saw a few blurbs here and there, but nothing conclusive...
Well, according to Canon no XXD camera will focus with the 100-400 and 1.4x converter, since you'd be shooting at f/8. However, if you tape the pins (google that) you can get autofocus to return on your 20D. The 40D won't let you do that with the center AF point, but will with the others.
