Can you guess which one is which?

It is raining like crazy here and I was kind of bored so I decided to do a quick and dirty comparison between my 10.5cm f/2.5 Nikkor-P and 105mm f/1.8 AIS Nikkor. I cut a notch in the aperture ring of the 10.5cm so I could mount it on the D850 and meter with it, a pretty easy task using a Dremel and cut off wheel. The hardest part was figuring out how the get the aperture ring off! The f/1.8 is an insanely sharp lens so I was pretty much expecting it to blow out the 1964 vintage 10.5cm. To my great surprise (and delight), at f/8 they are nearly indistinguishable! Nikon got it right even 57 years ago. There is no post processing of either image except to combine them into one image and resize them to a size that Nikonites will let me upload.

See if you can figure out which one is which:





Since Nikonites reduces the hell out of large images, a larger sized image (100% crops) can be found here:

https://www.flickr.com/photos/185644121@N08/50959531383

The photo on the left has slightly better contrast on the yellow flower center.

I would say it is impossible to notice any real difference.

The background of the one on the right either appears to be slightly sharper or has a little more contrast. No idea which is which although the one on the right would be my preference.

Ok, the one on the left is actually the 105mm f/1.8 AIS Nikkor. On paper (MTF tests) it does better than the 10.5cm but in practical usage I doubt you would see any difference unless there is a bright light in the frame at which point the multicoating is far better at preventing flare and ghosts. If you look at the rust on the support, it does appear that the f/1.8 is a little contrastier, but the differences are very subtle.

Look like the post (the straight-up part) in the left is more focused. I guess the left one is shot by 105mm.