I was in a camera store recently asking about the real value of the Canon image stabilizer (IS). I was told that one should always turn the stabilizer off when using a tripod. Is that true? I would love to hear your opinion on this.
That depends on which Canon IS lens you mean, Jackie. The pro calibre (L-series) IS telephotos were designed so the Image Stabilizer will work well even when the camera/lens is mounted on a tripod. By the way the same applies to certain high-end Nikon VR lenses as discussed in Tripod mode – Nikon. The relevant Canon IS lenses and some Nikon VR lenses are equipped with a feature that automatically detects if a tripod is being used and either disables the stabilizer or switches to a different stabilizer mode. Some of the pertinent Nikon lenses provide a Tripod option on the switch used to activate the Vibration Reduction system.
With lenses that do not include either feature, be sure to turn the Image Stabilizer or Vibration Reduction off when using a tripod. The reason for this suggestion is simple: when the stabilizer system cannot find vibration, it will create vibration, as Chuck Westfall of Canon USA told me a few years ago. Since a monopod does not provide equally great stability, any lens with a stabilizer system should work fine when this accessory is used.
You may not really need the image stabilizer’s Tripod mode when using a large/rigid support accessory, except on very windy days. However, the system can be useful in high magnification photography because it can correct even for the minimal internal vibration caused by the camera’s shutter movement or reflex mirror slap. Of course, if your lens is not equipped with a Tripod mode or an automatic tripod-recognition feature, be sure to turn the IS or VR system off whenever the camera is mounted on a solid support accessory.