I got a canon 20D, I would like to buy this lens, but I have heard of focusing problems with the 20D. Any comment regarding this will be most welcomed, thank you all in advance. Walter.

I've heard that older Sigma lenses (you might get them second hand) need chip upgrades to work properly with the AF system in the newer Canon cameras.
But apart from the lower AF speed of the Sigma lens I tried, it was focussing fine on my 20D.

There are a lot of reports of focusing problems with the 20D with a variety of lenses due to some defects in the autofocus unit, but I haven't experienced these first hand.

I had my first 20D replaced bevause of AF problems, but that was with all Canon "L" series lenses.
So I know that when I got hte second body it was workign with Canon lenses and with Sigma.

I haven't found any focussing problems with the 20D or my 350D for that matter using either Canon L series lenses or my Sigma 18-200mm

Jurgen
Australia