Should IS be activated with tripod support?

I just switched camera platforms to Canon for bird and sports photography. I’m now using a Canon 7D along with the Canon f 4-5.6 100-400mm lens with built in IS. While I’d love to use a 500mm single focal length lens for birds, the zoom is more useful for the sports shooting that my work occasionally requires. Plus my kids’ soccer seasons start real soon.

My new-to-Canon question is whether the lens’ IS function should be kept activated when using a tripod and shooting moving subjects like sports and birds? The lens is mounted on an Acratech ballhead on which I have set very slight tension, if that matters.

Alternatively I’ll use a monopod now and then, with the lens directly mounted.

Thanks.

ME

Typically with that lens it's recommended not to use IS while on a tripod (due to positive feedback, newer versions of IS turn themselves off when they detect that there's positive feedback). However, if it's very windy, or if you are actively holding the camera/lens and moving it around, it can help - best is to just try it for your specific set up if you're not sure and see what the results look like.

Some lenses, (the 300 f2.8, 400 f2.8, 500 f4, and 600 f4, for example) can be used on a tripod with the IS turned on.
Other lenses, especially those with earlier versions of the Canon IS system, cannot. In those lenses, the IS system may be fooled into correcting for movement when there is none, and the result is a blurry image.

Use IS mode 2 if panning horizontally. You might consider mode 1 if you are not locking down your ballhead for each shot. I leave IS off for the most part because constantly recalibrating made it difficult to get as many shots as possible before a bird would fly away.

I use IS1 (xy stabilization) almost all of the time with my Olympus E-3, 300 +EC20 and Wimberley I setup. I don't believe there have been any drawbacks.