I have several process type lenses off of copy cameras, and I thought I would try a couple as enlarging lenses as I have read a few threads describing them as acceptable. Problem is, I can't get any of them to focus with the aperture opened up. They look sharper stopped all the way down, but just a blur opened up. I figured I must be doing something wrong. My enlarger is a Durst 138, and the lens in question is an Apo Gerogon 240 (among others: Konica Hexanon GRII 150mm, Eskofot Ultragon 210mm). Trying to focus a 5x7 negative with two 240 condensers. Any suggestions, or are these lenses useless as enlarging lenses?