Quote Originally Posted by Dougjgreen
I don't know how they stack up statistically, but there is FAR more anecdotal evidence around about sample variation in Sigma lenses than about any other brand, Tamron would be next worst. BTW, what does that have to do with 4/3 sensors being "bad"? They're not, they just have a roughly 50% higher pixel density than comparable resolution APS sensors - which lessens the size of the photosensitive parts of the pixel, making them somewhat less light sensitive.
True, also demanding better lens to achieve those good results. 10 megapixels on an APS sensor vs 10 on 4/3, put an identical lens on each and the lens problems will be more noticeable on the 4/3 than on the APS.

Thanks for the info on the crop factor.