im a sucker when it comes to MTF charts...
can someon explain what he reads out of the MTF chart?
From what I understand, Sigma's MTF charts only provide result for the lens wide open (this is according to Sigma's own notes in their MTF Chart guide), and performance looks great assuming this is the case. It basically matches the performance of the 35L stopped down to F8 (judging from Canon's own MTF chart) - which makes me think that I must be reading Sigma's chart incorrectly.
But seriously, that's too good, so I don't think that it's right. I'm guessing that Sigma's chart is actually stopped down performance, which case it pretty much matches a stopped down 35L. Either way, IQ should be pretty good.