In my eagerness to get taking pictures i unzipped my lowepro backpack at just the wrong angle and sent my d70 and sigma 70-200 crashing to the ground.Fortunately it was damp soil and all seems ok but for a noise from the mount end of the lens when the lens is tipped upside down and back again.This happens on or off the camera body.I am not sure if this is normal or a bit of damage i have caused.Can anyone confirm either way?...Thanks in advance.