I note with some interest that color changes quite a bit between enlarger lenses. While waiting for the Jobo to come up to temp. today I decided to swap lenses between my Leitz and Beseler. I swapped a Nikkor 50 2.8 for a Rodenstock 50 2.8. I left the enlarger head the same height and focused. The Rodenstock is a different body height which created a tighter crop. First test print (of the same neg I printed last night and never moved) was 1/2 stop brighter so I corrected the aperture for that (never changed the timer). Well, the exposure was right compared to the print with the Nikkor, but the Rodenstock printed much cooler skin. I always warm my lamp up with a couple timer runs just before I get the paper out too, so I don't think lamp temp. caused it. So, for those of you doing multiple formats, are you staying with one brand of lense with the same coatings etc. so as not to have the color bouncing around between lenses -- or did you figure and write down the filtration value differences? I edited this because I forgot to mention that the Rodenstock appears to be slightly sharper than the Nikkor too.