I just got a Beseler 23C enlarger and I am looking for a set of contrast filters for it. I can certainly get a set of them on line but I just had a thought... I work in a theater. It's both a movie theater and a legitimate theater. Consequently, we have scads and scads of Rosco gels floating around. We have a whole drawer full of scraps we use for small projects and, sometimes, we even throw out gels because we don't have room for all the scraps we accumulate. That's what got me thinking. Does anybody have a list of which numbered Rosco gels can be used for contrast filters? We also have Lee and Gamcolor filters as well. We could always order certain colors of gel if we need it but my main thought would be to put some of the stuff we have lying around to good use instead of tossing it out.