I exercised my 28 - 135mm by zooming out from 135mm to 28mm and immediately focus on something nearby. understand that the lens motor will work and slight jerk will happen while focus is being acquired. I noticed that other then the motor going to work, the image through my viewfinder displaces upon the completion of the AF. Is this normal for a Zoom Lens? Is this behaviour what people call the "counter torque"? Pls help me out here. Thanks a million!