Here's what I've been waiting for - a 50L to 50A comparison from SLR Lounge
I think it's enough to convince me to cancel my pre-order. The Sigma is sharper, but not shockingly so, and the Canon's bokeh is slightly better (IMHO). The Canon also appears to have ever-so-slightly better contrast, while the Sigma has better CA control, but again, only by a hair.
The other thing I've learned is that you'll have buy the USB dock to enable full time manual focus (which I guess isn't standard for Sigmas). That's crappy.
The 50L has killer build quality and USM in a much smaller package and I don't think the Sigma is worth 950 of my dollars for such subtle differences at f/1.4 in what for me, is a portrait lens.
I guess I can't cancel it till the 24th, so I'll keep my mind open until then, but I think I'm going to cancel and resume the 50L II vigil
This is exactly what I expected. Sigma very slightly sharper, Canon better bokeh.
IMO no comparison if price not an issue, the Canon f/1.2L is the better lens. Although I got my Canon for $1200 during the rebate season.
* Minimal difference in sharpness/CA
* Canon has better bokeh
* My bet is on Canon for faster autofocus
* Canon does f/1.2, sigma does not
* Canon is much smaller, and probably built better
you can take a look to a more scientific review
the canon 1.2L is destroied on sharpness in the corners
The Sigma 50/1.4 Art's sharpness holds up very well against the sub-$2,000 competition, as well. At ƒ/1.4 and on a full-frame camera, it pretty well blows all of the others out of the water. The Canon 50/1.2L is pretty sharp in the center, but the corners are extremely soft.