A comparison shot taken with my new 40mm f4 Nikkor D, the same scene was also shot with my 40mm f4 PS Zenzanon to be posted at a later date.

The back I was using has a light leak ( seen on the left side of the image). It's a 40+ year old back from a S2 and will be retired.

Kodak TMAX 400 developed in TMX developer.

Update: The portion on the upper right is blurred like the Zenzanon image. Coincidence?

Compare to next image.

Update: I found light leaks in 3 S2 backs. Buy S2A backs when shopping. 6 digit serial numbers vs 5.