Minolta MC 58mm f/1.2 Rokkor-PG ("single-coated" radioactive early version with chromed filter ring)
Minolta SRT-102 w/ mirror lock-up and stopped down diaphragm*
Vignetting = B- @ f/1.2, B+ @ f/2, A @ f/2.8 and thereafter
Distortion = slight waveforming with a slight barrel tendency
Aperture Center Corner
f/1.2    C-     C
f/2      C+     C+
f/2.8    B      C
f/4      A      B
f/5.6    A+     B+
f/8      A      B
f/11     A      A-
f/16     B+     B+
Notes: * equivalent to "mirror and diaphragm prefire" procedure attained by use of self-timer on late model Olympus bodies. Moderately high contrast at f/1.2 to f/2; high contrast at f/2.8; very high contrast at f/4 and f/11 to f/16; extremely high contrast at f/5.6 and f/8. This is a metal focusing grip model with radioactive rare earth glass in the front of the lens. As with all rare earth glass from the 1960s and 1970s, there is a yellowing with age, due to side effects from radioactive decay. Thus the lens produces warmer images on color slides than does the later version below. Paired comparison with the later version (below):
differences in SQF grades significant at the 1/3 grade level. Outstanding lack of vignetting (i.e., light falloff) for a super speed lens, likely due to the large front elements (compared to the more petite 50mm f/1.2 and 55mm f/1.2 Zuikos).