Originally Posted by alexandru_voicu
Now I have print with it. I have an El-Nikkor 50/2.8 and I want to see whether I detect any improvement.
You *might*, but it will have to be at 11x14 or larger, perfect enlarger alignment and using a glass carrier, the EL-Nikkor is no slouch.
I own the 50mm 2.8, 80mm 4.0, 90mm 4.0 and 150mm 4.0 Apo-N enlarging lenses and they are no doubt regarded as the best in the biz. But they were also primarily designed and popularized with the reduction of color fringing in mind for Cibachrome, type R and type C color prints.
If you are just doing black and white then most good modern multi-coated enlarging lenses will more than satisfy. But yeah, the Apo-N's are really all anyone will ever need and they deserve the reputation they get.