Quote Originally Posted by StoneNYC View Post
The SCS lenses are specially coated and supposed to be better (for back then) than non-coated.
Coating lenses started much earlier and there is no uncoated Canon lens than can be fixed to an FD-bayonet, thus including the R-lenses from the late 50's.

Canon indeed changed in the 70's from SC coating to SSC coating, which means from single-layer coating to multi-layer coating.