Why should IS be "off" when using tripod?

[RovingEyePhoto]

I am shooting indoor macro this winter, and have read from various sources (and my Oly E-3 manual says) to turn IS "off" when mounted on tripod. I understand turning horizontal IS off when panning, but why turn any of the IS off when shooting still on tripod. I shoot a lot with center post set to horizontal, so there invariably is some latent movement out there at the end of the beam, so why not use IS to counteract? I have thus far left IS on for still shooting on tripod, and shots appear sharp at screen size, but haven't yet processed at 100% size in PS, so maybe I'm fooling myself. Thoughts?

[Moogle Pepper]

If you use IS on a tripod, the IS system will get confused.

[bauerman]

Here is one the better explanations that I have ever read on the subject from someone at Canon that know a things or two......

Canon’s Chuck Westfall explains it well:

“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.”

This may or may not apply to the Olympus system that you are using - but I thought that I would throw it out there anyway...

[jonh68]

IS shakes to compensate for shake. When there isn't any shake, it still shakes causing blur.

[RovingEyePhoto]

Thanks to all of you. It may be that the Canon concept regarding moving lens groups doesn't apply to the Oly in-body moving sensor, but since the E-3 manual says to shut IS off when using a pod, possibly it does. "Threshold" I guess is the important term here, do I get enough shake with the camera 10" or so out on a horizontal center post to trigger the desired IS response (not so little movement that the IS is "confused")? My macro rig is only about 3 lbs, E-3 body and Zuiko 50mm (100mm equiv) f/2.0 lens (small lens, 4/3 helps), and legs/head are Manfrotto 190CXPRO3/ReallyRightStuff BH-40, so small load and solid support, but the load still is hung out there so inevitable vibration does occur. I think my proof will be to PS some existing shots at 100% to see in finer detail exactly what I got leaving IS on, and take it from there. I'll post the conclusion for whoever's interested.

[sherijohnson]

I am glad I took the time to read this and I have confirmed that all of my cameras advise to turn off IS if using a tripod, at least now I know why. It does make sense.

[pyry]

I think Canon at least tries to make their stabilizers detect mounting to a tripod and stop - but it doesn't quite work, it's still best to turn IS off.

Tripods hold the camera rigidly enough to push the IS into a feedback loop - the system was designed to be held by something rather more soft and squidgy so the corrective movements are simply set up wrong for a tripod.

[Awais Yaqub]

So if you get invest 500$ more in IS version of 70-200 it will act like non IS version if you use monopod ? :scratch

[pyry]

So if you get invest 500$ more in IS version of 70-200 it will act like non IS version if you use monopod ? :scratch

Monopods are another story I believe. I don't have one so I can't test, but I've heard that you can keep IS enabled on a monopod.

As for tripods, yes, IS is of no use.