Archived from groups: rec.photo.digital.slr-systems (More info?)
"you know who maybe" <nguser2u@spamnotAOL.com> wrote in message
>I know my Rebel will not autofocus my 100-400 at f/5.6 with my 1.4x TC (at
>f/8.0) but it works fine on my 1D (without taping over pins of course) What
>about the 20D, and what do you call this?
Only the 1 series will AF at a minimum aperture of less than 5.6, i.e. f8.
The 20D is the same as the Rebel, f5.6. Unless you use a nonCanon TC, like
Kenko, that doesn't report the correct aperture to the camera. Then it will
AF, albeit not well, at apertures smaller than f5.6.