I'm new to LF so forgive me if this is a stupid question.

I need a good, cheap filter holder for my LF lenses. Since many seem to have NO threads on them, I assume there is some other way to get a filter in front of the lens. In a few books I have seen examples of clamp on gel and "cokin style" filter holders, but there have been no brand names associated!

Any help? I already have several Cokin A filters (hey, I'm cheap). So anything that takes them would be a BIG help. I could also move to the P size.