I'm not sure what I"m supposed to remove on this lens. There doesn't seem to be anything to grab onto to unscrew. On my 50mm Elmar, there's a spanner ring front and back. Here, nothing that I can see. When you refer to the decorator ring, do you mean the black one with the identification information? There isn't so much as an indentation in it and with the curvature of the lens I don't know how to grab onto it.