Long post, but thanks if you are able to follow along! A while back I made an attempt to calibrate my old Beseler Dichro DG colorhead to my particular printing materials. I did a series of projection prints of a stouffers 21 step wedge onto 4x5 sheets of papers, and various filtrations, and tried to make a curve of the resulting contrast range vs. the changes in filtrations. Recently, reading an Ilford data sheed for multicontrast paper makes me think I may have made a mistake. I started my wedge print series with a maximum of 130 units of yellow, no magenta, and decreased my yellow by, I think 20 units per print, then continued on with 0 units of yellow, and steadily increasing magenta. The curve was somewhat irregular, but gave me enough data to figure rough approximations of equivalent paper grades. Now I'm thinking I could have done better... The Ilford data sheet I read suggested yellow and magenta values to achieve grades using two different Durst heads, a kodak value, and a Leitz Focomat V35. My questions: Does my Besler DG Dichro use the equivalent of "kodak" filtration values? Also, my testing didn't mix yellow and magenta, but used only varying amounts of either one. The Ilford data sheet seems to recommend combinations of both Yellow and Magenta. Is this only to keep the speed point similar, or is there other reasons? [update- a close look at the data sheet implies that using both colors, though requiring longer exposures, keeps the exposure times closer together for different grades.] Do most of you mix these two values in different ratios, or use either Yellow or Magenta only, but in varying amounts? I guess this would explain my not so smooth curve in my plots of the contrast range vs change in filter values, described above?