IS

The info manual says to turn off the IS when not in use, can it drain the batt with the camera off? Can it cause any probs if left on?

thanks, Pete

I always leave it on unless on a tripod. Never had any battery problems. I am using the battery grip though.

I only turn on IS when I need it. IS is a mechanical, moving device. I don't want it running if it's not needed. Not for battery concerns, but for the lifetime of the IS "engine".

I believe the IS is only activated when you press the shutter button. When looking through the viewfinder the image does not stablilize until you press the shutter button. It also continues to run for a sec or two after you release the shutter. Which is why you should give the IS a sec to spool up before you snap the shutter. I could be wrong but that is the way it seems to work for me.

I'm not exactly sure what it means but has anybody else noticed this. Turn off the camera with an IS lens installed. Remove both batteries from the grip.

Now, put back one of the batteries and pay close attention to a sound coming from the lens. It sounds like the IS mechanism just came to life, doesn't it? And it does it whether the IS is turned on or off.

I know the IS 'motor' only come to life on my 75-300 when I half press the shutter, quite a noticable noise in quiet conditions.

May or may not be related, but turned my D60 on after a couple of idle days with the new 100-400 on it (switched off) = absolute dead flat batt.
It was the oldest battery I own (2002) but haven't seen this before...
Will see how it goes...

I often leave my 75-300 IS USM lens on my 20D for days at a time and haven't noticed either that it kills the battery faster or that it makes any noise except when I press the shutter release button half-way.

I bet the sound PacAce noticed is the AF motor syncing rather than the IS motor, but that's just a guess on my part. I've never noticed any noise from any of my lenses when I change lenses with the power off and I turn the power on.

And I have read that to avoid lockups it is best to change lenses only with the power off, so that is all I have done.