I know it sounds silly wanting to print so "small" a format on such a large format enlarger but i've been having some problems focusing my 50mm lenses (for large enlargements from 35mm ) using the Durst 138s. I have the right condencers installed but cant get the bellows "short" enough to focus. Are they specialized 50mm lenses for this enlarger? I tried a Meopta Anaret and an old Componon. Would one need a lens with a longer screw thread? Regards, Mario.