From
http://pdf.textfiles.com/manuals/CAMERAS/VINTAGE/pentax_spotmatic_ii-1.pdf, PDF page 24:
Quote: Primarily made for use with the Spotmatic II, the Super-Multi-Coated Takumar 50mm f /1.4 can also be used with the original Spotmatic, the models SL and SP 500. Further, it can be used with only two other cameras: Asahi Pentax SV and S1a with an orange-coloured R marking on the film rewind knob. Use with any other camera will damage the rear element lens.
"
Use with any other camera will damage the rear element lens"?
Does the
S-M-C Takumar 50/1.4 have a protruding rear element that doesn't clear the mirror on early Asahi Pentax bodies?
—DragonLord