Quote Originally Posted by Leigh B View Post
To properly identify the thread you also need to know the pitch (the distance from one crest to the next).

It's probably 0.75mm, but no guarantee.

- Leigh
I don't know how to find out the pitch, but it might not be necessary since I believe the lens came with the locking ring. I'd have to head home and into the darkroom to find out, though... Thanks for the tip.