For anyone who has this lens (the non usm one) when I switch to manual focus and adjust the focus ring it sounds like the motor is still engaged to the automatic focus. All my other lenses make no sound and it will turn very smooth while this makes a bit of a whining sound and is fairly stiff when turning it. Its still under warranty so I just want to check to see if i messed it up somehow or if this is normal. So what does yours do in manual focus?

