Questions repeatedly arise about whether or not Image Stabilization (IS), available on a fairly wide variety of Canon EF lenses, should be turned on or off when mounted on a monopod, tripod, etc., and whether or not the lens would be damaged if an incorrect choice is made. This information is provided to address these issues and concerns.
When the camera and lens are mounted on a monopod, it is recommended that you should keep IS turned on as there is still a fair amount of residual motion, and that IS performance will help dampen that motion.
For tripod use, things get a little more complicated, as the IS technology itself has progressed over time, and different lenses use varying forms of this feature. First, no damage will occur if IS is left on, under any circumstance. The primary question is whether or not it is advisable to leave IS turned on or off when mounted on a tripod.
Through a post by Alan Hartmann at the Canon SLR Talk forum on Phil Askey's Digital Photography Review site, I was led to a site created by Klaus Schroiff: Canon EOS Lens FAQ. The main page can be found here. There's a lot of useful and interesting information there. One section addresses this specific issue, and with his permission, I am quoting this part in its entirety here (with a few spelling, format and grammatical changes). The original can be seen here.
Q: What about IS and tripods ?
A: There are some rumors about there that state that the IS gets damaged when activated on a tripod. This is obviously just nonsense. This is what you can read in the manual: "Do not set the image stabilizer switch to 'I' when using the camera on a tripod. Doing so may cause the image stabilizer to act erratically. Turn the image stabilizer off before using the camera on a tripod.". Further more this is only true for the following lenses:
Here is the explanation from Chuck Westfall (Canon USA):
"The IS mechanism operates by correcting shake. When there is no shake, or when the level of shake is below the threshold of the system's detection capability, use of the IS feature may actually *add* unwanted blur to the photograph, therefore you should shut it off in this situation. Remember that the IS lens group is normally locked into place. When the IS function is active, the IS lens group is unlocked so it can be moved by the electromagnetic coil surrounding the elements. When there's not enough motion for the IS system to detect, the result can sometimes be a sort of electronic 'feedback loop,' somewhat analogous to the ringing noise of an audio feedback loop we're all familiar with. As a result, the IS lens group might move while the lens is on a tripod, unless the IS function is switched off and the IS lens group is locked into place."
In 2000 Canon released the next generation IS professional lenses. These lenses feature a "tripod-detection" mode which means that there is no problem using IS on a tripod. Even more than that - IS will correct vibrations caused by the mirror operations of the camera. So far the feature is available on the following lenses.
... is the first IS incarnation
with an improved IS effectiveness of up to (officially) 3 f-stops.
Anybody having any additional information on this subject, please email me.