My experience with Canon 50 1.4 type 2
From what I can tell of the Canon museum pictures, the differences between type 1 and type 2 of this lens amounts to this:
Aperture ring - type 1 has tick marks at each aperture setting.
Type 2 doesn't.
Focusing scale: type 1 has only one set (in feet in the picture from the museum)
Type 2 have both metric and imperial measures on the distance scale.
Now here are some caveats from actually living with one.
1) Don't use the original Canon rear cap!
I bought one from maiku, who had it CLA'd in Japan.
I was upset to find that it didn't focus right.
Clarence Gass, my usual repairman, told me the answer.
The original Canon rear cap is so shallow, that if you rotate the focus ring much beyond minimum focus, the RF cam will jam up against the cap. You CANNOT put the focus to infinity with the original Canon rear cap mounted on the lens. Apparently, I must have done so, and what gave was the RF cam. It was indicating beyond infinity. So, this needed to be reset during the lens' servicing. I now use a nice deep Voigtlander rear cap if the lens is ever off my Canon 7s.
2) Make sure your RF is accurate.
The depth of field at f/1.4 is extremely shallow. You need to be sure that the lens cam (see above) AND the camera RF are BOTH properly calibrated.
In my case, I sent both the lens and my Canon 7s to Clarence to have this done. I've attached a photograph of how this setup images at 1m distance, at f/1.4.
3) 48mm UV filters and hoods
I bought the original Canon 48mm slim UV filter. It appears to be single coated on each side. B+W make a 48mm UV MRC filter with modern multi-coating, and this is what I use now. The B+W filter also has front threads, if you want to use a 48mm hood. The original Canon lens hood is the S-50, which is friction fit, with a locking thumbscrew. I went with this route. A 62mm push-on lens cap (Kalt, from B&H) will fit right on top of the S-50 hood.