I have been meaning to do this comparison for a while, and finally decided to give it a go. This is pretty informal, but all images are posted SOOC (shot raw and converted by ACR. Metering for highlights, so the darks are dark).
This is slightly unfair to the UMN, which is designed for a monochromatic light source. I was pretty close, though, to the specified working distance of 7 meters. I did one shot of my refrigerator magnets, a relatively flat surface, and one close up (handheld, not equivalent) of some flowers with bright reflections. I'm posting the original frame of each shot with both cameras, and then some extreme crops. Shot with a Sony A7r4 body with 62mp.
First the refrigerator. What is immediately noticeable is the difference in color rendition. I shot both with Sony's tungsten WB to have a fixed reference. The UMN is quite warm. The Apo EL Nikkor has a much more neutral rendition. What is noteworthy is how much better contrast the UMN has. The AEN looks veiled in comparison. Also I have found the AEN to have a tendency to flare that the UMN does not share.
In terms of center sharpness, both are mind blowing. I find that the AEN has a slight edge. Near the corner it is no contest. The UMN is slightly soft and is showing LaCA. It also has some LoCA, but both are pretty well controlled, given that we are at a magnification of ~200% in the center crop and ~100% at the corner. THe AEN is stunning in how sharp it is across the frame, without a hint of any CA at all, at least in this situation. While my hat is off to the AEN, I have to say that I find the rendering of the UMN with its saturated colors and deep blacks very attractive.
The flower shots are not equivalent, but what I find interesting is the rendering of OOF specular highlights. The UMN is showing some serious chromatic aberrations (though again, relatively small, considering). There are hints also in the AEN, but they are miniscule.
Another great contrast is, of course , in the physical size: the UMN weighs in at 2200g, with the AEN at 140g, a huge difference. Strangely, the review at Coinimaging reports fuzzy corners on the AEN, but they were testing the old version. To my eye, there is barely any difference in sharpness between center and edge, but perhaps at closer working distances things change (though in that case the lens is built to be reversed).
