I got my new 50mm 1.2L from B&H today that I bought to replace a refurbished one that I returned to Adorama last week. I returned the refurbished one based on a focus test I did using it. I also did a focus test with the new lens to be sure that I got a better one this time.
All of these were shot with the 5D Mark ii, focusing on the center line using the center focus point. Images are zoomed in to 100%, no sharpening applied at all in PP.
Right side is closer to the camera left side is farther away
50mm 1.8 ISO 640 ss 1/200 f/1.8
50mm 1.2L Refurbished ISO 400, ss 1/320 f/1.2
Just to be confusing I forgot how I shot it before and it is reversed here left side is closer to the camera and the right side is farther away
50mm 1.2L New ISO 200, ss 1/200 f/1.2
When I looked at these images I saw that the 1.8 was sharp, but it focused in front of the center line by a bit. The refurbished 1.2 wasn't sharp at all, nothing in the image was in focus, though it looked like the least out of focus area was a bit behind the center line. The new 1.2 on the other hand is much sharper, maybe shifted back a little (note how the 1 on the right is more in focus than the one on the left of the image) but MUCH sharper overall than the refurbished version. With just a little sharping in post the new 1.2 will be perfect!
I found the focus test instructions here.