I don't think that either of those is likely - the base lens isn't interchangeable on these as far as I can tell. It doesn't screw in like on the EX series. The optional lenses are just add-ons that mount in front of the base lens, and I don't have any of those. As far as not turning far enough, if the focus ring didn't turn far enough I'd think it would increase the MFD, not decrease it.