Canon 100-400 IS lens on D60 and EOS-1N

[peeps27]

I recently bought the Canon 100-400 IS primarily for sports photography and am slighlty disappointed that it has a certain "clunkiness" during focussing. I have read elsewhere that if using a tripod or monopod (in my case) the IS should be turned off. Is this why it is clunky? I am on the point of returning it to a dealer for checking it out. I can't see any advice about this in the manual.

[meckstein]

The "clunkiness" you hear is the "IS" doing it's job. Canon reccommends that you turn off the IS when on a tripod. I never do and have had no adverse effects.

[peeps27]

Thanks for the quick reply. Sorry for being thick but when you say "I never do and have had no adverse effects" does that mean you keep the IS on and you don't get the clunkiness, or you never switch it on when using a tripod?