Glad Mark, and I do enjoy your posts a lot, so keep them coming, and I guess you did have an insanely good copy of the Canon 50mm 1.2... ;)
Joseph what most need to understand that when it comes to Lenses it is never as simple as that vs the other, NEVER.
Still glass does indeed need to be good so to resolve imagery from, well, STILLS, yet one can not EVER really compare Still glass to Cinema glass, in depth and saying that Still is better the Cine glass, it will never be!!
There are several reasons for this, one is of course the Build it self, and not talking about Build quality here, but about how the actual lens is build!!
Cine glass has to overcome many more obstacles then what Still glass is originally designed for, and for this you find all kinds of Lens Defects in Still glass, much less prominent or insistent in Cine glass.
Such as Super Color Matched Optics, NO CA, NO NO Barrel distortion, NO Focus Breathing, well, some Cine do, but the best don't, NO Light fall off thru out the entire Focus Range, which in the best Zooms is also maintained, etc.
the list is long, and for this Cine glass is Cine glass and Still glass is Still glass.
Can Still glass be used instead of Cine glass?
Yes of course, but only for those on a Budget or after a particular look given by a particular lens, or for reasons of weight and size, were the image quality is not as important.
Sharpness is only one part of the equation, the capable resolving resolution is the most limiting factor in some lenses, and Jim already pointed that out, more then once, so I don't have to go in to it here.
So is not that Still glass is not sharp in off, is just that, it is only but good in off, and for me good in off will never cut it, not when it comes to my images, I except no compromises... IF I CAN.
Again, its okay to use, of course, but there is a difference and it is not a small one.
I'm surprise that Mark has gotten a FANTASTIC copy of the Canon 50mm 1.2, as I had 4 and tested against other 4 RED PRO PRIME 50mm, and my Master Prime 50mm, and the only one that was sharper was the RPP.
But not all lenses are built equally, so it could be and I trust Mark that it was.
But Joseph, you must be more careful in your assessments, and BTW, lots of Photographers do use Cine glass on EPIC... ;)
What I am curious is to see how Medium Format glass will do, no big expectations, but I know for fact that will do bounds and leaps better then 35mm Still glass, but that too will never match the Cine Glass overall capacity and qualities, again, SHARPNESS been only but one element of the MAT in a GOOD LENS to produce a great image that can stand out in large prints and in a large 4k Screen.