the problem is when you squeeze the hood to unscrew, since it is so tiny, you are putting pressure on the screw thread from your fingers. The best way to do it is using a rubber cork. If you don't have one, find a mouse pad (the one for your computer, not the mice the animal) and turn it arround, it should have the rubber matterial on the back. lay your lens with the hood down on the mouse pad gentally and then turn. it should come off.