Please consider I'm on crop sensor. Should I go for it? The two extra stops over my 17-55 f2.8 would be nice, but if I have to stop down to f2.8 to get decent results, it may not be worth it... if the AF will fail me within two months, it certainly wont be worth it. On the other hand, I really like the alternative of low light shooting.
The other option is wait 6 months or so (perhaps even more) and get one of the 35mm options that would be a bit more of a 'normal' lens on my T2i (the Sigma 35mm f1.4 appears to be a FANTASTIC lens... everyone is jumping through hoops for it!).
I owned a 50mm for a few weeks for my 7D. I found it too narrow for my shooting, keep in mind I do not shoot portraits though. I bought a 35mm and loved it, although I still longed for the 24L. The 35mm seemed even a hint narrow for my liking.
If I were you, I'd wait for the Sigma 35mm to be reviewed. The easiest way to think about which focal length, is go shooting with your 17-55 with the zoom ring gaffer-taped at full-zoom. Then do another shoot with it gaffer-taped at 35mm.
IMO, the 35mm is too narrow for non-portrait / indoor sports purposes on the crop sensor.
My thoughts though are: Are we about to see a 50mm 1.4 replacement? If so, might it be a 50mm f/2.8 IS? If it is a 2.8 IS, I don't think it's fast enough for most users of this lens.
I just bought a 6D, and will be in the market for a fast 50 to complement my 35/1.4 and 40/2.8. Don't know if I should wait or not...
