Beseler 810 MXT enlarger

Nick: A couple comments which sort of halfway answer some of your issues. (Well, nobody else has responded...) I have the Beseler conversion kit on the 45V-XL enlarger, and it works very well. At least with that set up I have used the Beseler branded (Rodenstock) enlarging lens (240 mm) without light fall off issues. I have also found that the enormous Nikkor 210 lens will cover an 8X10 and be sharp out to the corners. When you use it, you don't have to crank the upper stage up so far. (The only problem I have had with the V- XL is that the top stage droops toward the front when cranked up all the way with the big head on it. This is easily solved with a little prop on the front and a level at the beginning of the printing session. You shouldn't have to do this with a piece of equipment this expense, of course, but it has always been like this and I never bothered to figure out exactly why.) After I converted the tube in the head to the Aristo V54 tube, I found printing times acceptable in the print ranges you are talking about.

The 240mm lens sold by Beseler is an Apo Geragon process lens it really does not compare in performance to the 5.6 Rodagon 240mm which fully covers 8x10" and is rated for 2 to 8X magnification.

This lens has a 72mm mounting thread as opposed to the 50mm thread on the Apo Geragon. Also the process lenses work optimally at f22 if they are shorter then 600mm which is an uncomfortable aperture for printing.

The Rodagon hits optimal aperture much sooner and is considerably brighter for focusing as well as having the illuminated aperture scale.

I've been looking for a good used 8X10 enlarger. Have you looked at the Zone 6 model?