Hi, i just saw the latest "lens accessories" video in the EF101 video series. The one thing in it that I haven't heard before was a general tip towards the end (around 4:35) of the video: For IS lenses, one should turn IS off before taking the lens on/off the camera body. I have managed to stay completely unaware of this until now, and I'm not sure why one should do this. Could anyone explain the reason why one should set the IS switch to OFF before removing a lens?