I have an Omega Concept Six enlarger. I would like to set it up for medium format. It seems like the condenser lens is big enough for medium format, but it only came with a 35mm negative carrier and a weird 4x4cm square one (?). It has some Rodenstock El-Omega 50mm f/3.5 lens on it. Even assuming I get a 6x6 negative carrier, I will probably need a 75mm lens. Can I just get any old enlarger lens, or does it have to be a special one for Omega enlargers? Could I interchange lenses between this enlarger and my Beseler Printmaker 35 enlarger?