Originally Posted by The1
I don't find AI servo the most usefull focusing mode, so may not be the best indicator depending on camera body.
I've taken lots of pictures where i was focusing on an animals head and gotten it's tail in focus with AI servo... it's just too sow to keep up.
The 7D has a much more acurate system, but i've never taken the time to bother testing it, just because i don't like shooting with it activated.
p.s. I've never heard a lens make a clicking type noise like that. the Non-usm lenses are lounder, but they don't sound like a machine gun with no bullets in it.
I've been pretty successful using AI servo in the past with other lenses. I only use it when tracking moving subjects, though.
My nifty-fifty isn't as loud as this thing is. I'm waiting to see if the guy can come up with the receipt before sending it off to Tokina for evaluation/repair.