Well a lens like the Symmar drops off at cos^4 and the Super Angulon drops off at cos^3. So I would say that a 120mm Super Angulon would have less fall off at any angle off the center line. Center filters aren't used on Symmars because they don't have the kind of wide angle coverage that would need them. They only cover 72-75 degrees compared to the 100 or so for the Super Angulon.
Originally Posted by jbbooks