75mm f/2.8 just about wide open on the shortest extension tube, Ilford Delta 100 in Fomadon Excel (Xtol) undiluted
BTW - I was using the 220 insert here, with the little doohicky reversed for 120 film. It works, though after the 15th frame the camera advances to 16 and locks up the shutter, instead of winding on to the end. This is OK, as the film is nearly all wound up in the take up spool - though I'd advise to take it out in subdued light. I will put the 220 insert back in its original state and maybe someday buy some 220 film.