Its pretty heavy, and made a couple years back. It has a fabulous Red ring on it, and can be made to F/1.4 if you'd like.
Any idea what it is?
Yes I own all 3 50mm lenses and the 50 f/1.2L isn't worth $1699 what it was when new. Stopped down and I can assure you it performs no better. Now, apertures wider than 2.0, yes I agree it is superb. IQ isn't WORSE than the 1.4 or 1.8 stopped down, but it isn't better. It's the ONLY L lens that has this characteristic. And with today's RAW processing, I have duplicated IQ at f/1.4 between both lenses on the same subject. Would I sell my 1.2L? No, I love the bokeh it produces below f/2. But I'm not going to pretend that it was worth the premium over the 1.4 for a second. You can't deny that the L version needs updated and secondly, that there is room for an update.
I can, and I will say that the 50mm 1.2L is the best, fastest, and sharpest 50mm SLR lens avaliable in the market today when shot from F1.2-2.8. Its the flamberge sword in the canon line-up, its difficult to use and specialist but once mastered, can be even more effective that traditional non-aspherical 50mm's.
And i've shot many, many different 50mm's and equivalents in Medium format 80mm's in hasselblads and yashicas. I grew up on 50mm's and I have to say the canon 1.2L is my favorite so far.