<p>I went through similar search for the optimum enlarging lens. This was a long time ago and I primarily used slow films such as Tech Pan, H&W EI 25 VTE Ultra grainless panchromatic film and several others.<br>
I started with El Nikkor 50/2.8 but did not like the results, tried several others including Leitz 50/4.5 focotar and Rodenstock 50 apo, I finally ended up with a very hard to find 63/3.5 Fax El Nikkor, not to be mistaken with the later offering 63/2.8 El Nikkor which is a ordinary enlarging lens. The 63/3.5 is single coated and was intended for microfilm applications, I bought mine about 30 years ago, at that time it was priced at three times that of 50/2.8 El Nikkor, the resolution is above average and it starts showing up in very large enlargements where other premium lenses just do not cut it.<br>
Vahe</p>