dtcls100
Well-known
I have the 50 1.2 ais. It is very good stopped down to f/2 and smaller. Wide open I find it very hard to use on my F2. The rate of misfocused shots is too high in my opinion, even when carefully focusing. I suspect there is some considerable focus shift, given that your viewfinder does not utilize the full aperture (meaning you focus at about f2.8 even wide open). If you hit it, its fun and looks nice. But more often than not, the image has little sharpness due to misfocusing, not due to reduced overall sharpness of the lens (which is to be expected).
Another possibility is that your mirror needs to be perfectly calibrated for this lens. If the angle is not perfect, you can theoretically also get misfocused images... So be aware that using the lens to its fullest capabilities is not easy.
No focus shift on mine, as tested on Nikon film bodies and Sony A7Riii. Takes fine photos even wide-open, although at f1.2, it is a bit dreamy looking, razor sharp at f2