I purchased the Panasonic 12-35 for a good price from DigitalRev ($999), but when I went to test the OIS, it didn't seem to make a difference whether the switch was on or off. Tiny purposeful jidders don't seem to be affected significantly by the position of the switch. Yet when I put the IS on in the OM-D, it does diminish the jidders. I tried depressing the shutter release for both, and also tried it on a GF3. Do I have a dud, is the OIS feature on the lens that much less effective than the IS built in to the OM-D, or is the OIS feature only active at the time of shutter actuation? Thanks for your help.