The C330 body I got earlier this year was from a portrait / wedding photographer who has gone digital. He was explaining the system to me and how he had used it for many years with great success. He ran into a problem with sharpness on one of the lenses (not sure which one now), and had sent it back to the factory for a check-up. The problem was as reported earlier in this thread. It seems the shims which came with the lens were not correctly installed. The same lens was returned and was "tack sharp" when he next used it, said this was a common problem with the lenses. The glass was excellent, but the shims would normally be out of adjustment due to an improper c.l.a. or tinkering by someone who didn't understand the lens.
This seems to me to be simply a manufacturing issue from years ago. With today's technology and tolerances, the use of shims would be an unacceptable,costly and unnecessary manufacturing procedure. In the past, it was just a necessary part of the "system" for production. tim