Just picked up a 135mm f4.7 Wollensak Raptar. Price was $10 and it works okay except that no retaining ring was present. I measure the thread diameter at 33.5mm. Are these retaining rings specific to a brand and type? Are they available anyplace or are they very hard to find?
Regardless, I will figure out a solution, but it would be nice to have a regular retaining ring.
The retaining ring from my 90 f6.8 Angulon is close but a bit too small.