What lenses take a 36mm filter?

[ColdEye]

I just purchased a red leitz 36mm filter on ebay. I thought it would fit my industar-50-2 (m42 mount), but apparently it does not. What lenses were these made for? I am planning to get a Fed 2 and a fed 50/3.5, will that fit it?

 

[Ralph Javins]

Good morning, ColdEye;

A good question. I am not sure about the lenses for your FED 2. There is also the point that one of the standard filter sizes is 35.5mm, which is very close.

 

[anon12345]

My Canon III has a collapsible Industar 50 attached. The yellow filter I am using is a push-on Ernst Leitz with a knurled locking nut on the edge. The inside collar measures 36mm.

Dann