Mounting filters on vintage c-mount lenses

[austinchimp]

I've managed to collect a few good c-mount lenses of different and unknown front filter sizes, and I was wondering if anyone knew of a good solution to mounting filters without a large matte box and without having to get unusual filter step up rings. Is there some way of attaching filters with a resizable or adjustable attachment on the front of the lens?

Ideally I'd be able to use a 62mm filter for example, on multiple smaller c-mount lenses. Has anyone tried using anamorphic lens clamps for example?

[Cinegain]

But... that's exactly why there are step up rings... You can get a set of them pretty cheaply. There must be one amongst those that will fit. Then place a sticker on the lens with the filter thread size for when you're using it next time. A clamp idea probably works too, you could even make one yourself, you just buy an attachment tube with filter ring for a compact camera and drill some holes in the base (or if there already are some, you might need bigger screws)... I 'm just not sure why you would though. Again, step up rings are there to negate said problem.