I have a recently acquired model, virtually unused.? I am?familiar?with most every other M model but not an M6ttl.? Lets say you cock the shutter and then turn the speed dial to "off'". Presumably, the light meter is now "off"--and then you press the shutter button--the shutter opens and when you release the button, it closes. Obviously the "bulb" setting which is adjacent to the "off" setting, is operative. Is this normal?