Quote Originally Posted by John Koehrer View Post
You're right. A Series 8 filter isn't threaded it's a drop in.
You got me there...! Almost: i haven't mentioned Series VIII filters with thread have i?

Anyway: the thread on the Hasselblad lenses taking Series VIII (or Series 63, as Hasselblad calls it) is not the same as the one on 67 mm thread mount lenses.
The thread on the Series VIII/63 retaining ring consequently isn't the same as that on 67 mm thread mount filters either.

As was mentioned: the two will mix. But only a bit.