What mm is a Series II filter ring? (second question on the same lens.... I know...)
I just searched through the two most definitve sources I have - the 2003 Calumet catalog, and B&W's Filter catalog, and there is no menton of a series II (two in Roman Numerals) or Series 11 (eleven) filter size. The smallest "series filter" listed is 4 and the largest 10b. There is no entry for either II or 11 in B&W's extensive adapter listings either... and those are *extensive* (why would anyone need a 49ESA to 49ESA adapter?)
Are you sure this is intended as filter size ... and not something like a "Whiz-Bang Special II" name?