Zeiss 50/2 (Milvus) vs. Summicron-R 50/2

[Airy]

The Summicron has a good reputation. A well-corrected lens, with no big flaws (except some flare when shooting against the light) , sharp wide open and quite homogeneously so. It can be found, or transformed, Nikon F-mount.

I had a check this morning, using D800 and performing a close range brickwall-type shooting. My reference lens would be the Zeiss Milvus.
Overall, there are few differences. The Zeiss is warmer (but less outrageously yellow than its predecessor, the 50/2 ZF II). Vignetting is similar; both display some low barrel distortion, Zeiss has the lesser one.

Well, wide open, the Zeiss has the better contrast and, doing some pixel-peeping, it shows better sharpness until the far edges. The surprize comes from the corners, where they are equal and, given that the Summicron has some forward field curvature (towards the photographer), it might even be a winner here if corners really mattered. As nobody places subjects in the corners, it does not.

It takes until f/4 to have both lenses levelling out, the Zeiss corners improving a lot, while the Summicron catches up in the center.

Further down, f/5.6 - f/8, the center sharpness of the Summicron seems to exceed the Zeiss. I'd have to re-test it in order to be sure, doing some focus bracketing etc. but at that level it does not really matter. On the other hand, the Zeiss has less CA and LoCA.

Overall, at this short distance, the Summicron is amazing, if you can stand fully-manual operation (no aperture coupling !). The Zeiss is more universal (MFD, flare resistance, smoother bokeh with 9 blades instead of 6, simpler handling) and is the king wide open, so for portraits of impatient or restless subjects, it is highly recommended. The Summicron does an excellent job for slow photography, fits in a pocket and won't empty your bank account as efficiently.

[toolazytotry]

I hope, since mirrorless cameras are becoming the norm and lens mount adapters are becoming just as common, that people start doing more comparisons between the best M mount lenses and the best F mount lenses on the same sensor. (Most comparisons previously have been on a Nikon DSLR vs Leica mirrorless)

[MEPER]

It could be interesting to know how far an old Nikkor 50/2 is from this performance. A bit stopped down a 50/2 can be very sharp but is probably not as flat field as the Leica and Zeiss.
I used a Nikkor 50/2 many years ago with a B/W film called Gigabit and 50/2 lens resolution at F/5.6 was quite impressing.

[Airy]

I own a Nikkor 50/2 AI and use it rather often on travel : the recessed front lens makes it an excellent lens for walking around. Besides, the 6-blade diaph provides interesting results at night. Wide open, it shows some blue fringing and, while usable, it is far from the other lenses performance level. Stopped down at 5.6, it is very sharp indeed.

[MEPER]

I have a link to a couple of scanned Gigabit film 24x36 frames shot with 50/2 at F/5.6. I used a Nikkormat FTN with mirror lockup and used self timer to fire:

https://pbase.com/mxp/gigabitfilm

There are two frames with some 100% crops (Tobermory and Lighthouse).
The is a full scan of Tobermory at the bottom (15 MB). I used a Coolscan 9000 at 4000 DPI. If I had a 8000 DPI scanner I think I could pull more information out of the frame. It shows that Nikkor 50/2 can be very sharp stopped down. It is possible to get a few of them and then pick the sharpest. There can be some sample variations.

I have a Summicon 50/2 for Leica M. When I probably some time in the future gets a Z camera.....I can try it out via an adapter...…..