Do you hear a slight "clunk" sound from the front of the lens when the IS activates, and again upon deactivation? I noticed this in mine for the first time last week. It is 10 months old with several thousand shots. There was also a faintly detectable "hum/buzz" when you put your ear on the lens tube. I had noticed my IS shots seemed unusually soft.
So, I sent it off to Canon on 12/31/04. I received it back today stating the IS was not working, and it was replaced under warranty.
The lens however still makes the noises, but my images look good . This is different from when I sent it to Canon.
I would have thought there was a relation between the "clunking/buzzing" and the malfunctioning IS that was replaced? I wonder if perhaps things were cleaned up instead of replaced?
The IS on my 100-400L also makes a clunking sound when it turns on and off. I believe that this sound is normal (although someone with more IS experience may want to confirm this).
This "clunk" sound is normal. I have this sound also on my 100-400. You would also see that image is moving a little at the same time. That's the IS kicking in and keep the image steady...
All of my IS lenses make that "clunk "sound and also a whirring sound, neither of which I had ever heard until I read this thread and checked all of them in the quiet of my den. When I'm out shooting there is usually so much ambient noise that the sounds go undetected.
