The filter size situation is absolutely crazy, and the lens manufacturers apparently don't care. It seems like nearly every lens I own takes a different size filter. I have five coupled lenses for my Technika, from 90-360mm) and there are FOUR different filter sizes, plus three uncoupled Dagors each with it's own Series filter adapter. I think that Kodak had it right with their Series Filters -- maybe we should go back to it. But I'm not sure that anyone even makes Series filters any more, and the step-up/down rings are available only in one or two sizes. Pardon my Primal Scream -- Aaaaahhhhggggggggggggggggg!