Does the image stabilizer on Canon lenses decrease the overall image quality?

Question

When I'm shooting hand-held during the day, when the light is strong enough for the camera to shoot at 1/2000 and slower (therefore the image stabilizer should be useless, right?), should I disable the IS on my lens, or should I leave it enabled anyway? What about cases when using a tripod, for example?

I know that IS consumes the battery a little more, but let's ignore this fact. Let's talk about the produced image quality.

Answer

It is documented that stabilization should be disabled when shooting from a tripod. This is because the stabilization system me try to compensate for inexistent movement and create a feedback loop. In this case you would lose image quality.

Sometimes it is done for you:

• Some modern high-end lenses supposedly detect when mounted on a tripod and turn off stabilization automatically. Disclaimer: I own no such lens, so I do not know how well it works.
• Pentax DSLRs automatically disable stabilization, which is provided by the body, when a self-timer or remote is used.

For high shutter-speeds, I am not entirely sure. There were anecdotal evidence that some lens-based stabilization system had trouble at shutter-speeds faster than 1/1000s and caused increased blur unless disabled. I have never seen it happen but I haven't tried every combination of lens and shutter-speed :)

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