I have a Minolta 16mm 2.8 fisheye, which has four built-in filters that are selected by rotating a selector ring. I used to use one of the filters for B&W regularly, the other two less frequently but since going to digital all I use is the clear filter.
Can anyone recommend a repair tech(prefer a craftsman if you follow my meaning) who could replace one of the least-used filters with a CC30M? This craftsman would have to have the capability to grind a filter to the correct diameter to fit the internal holder, and would ideally have some knowledge of the lens so I can first find out whether the filters are flat pieces of glass or if they have some convex/concave profile. It seems from the repair manual for this lens that the two faces of the filter are parallel but it is not stated explicitly.
I have an email out to Pete Ganzel on the subject, any other recommendations welcome.