I haveowned this lens for about 6 months now. It's a sharp lens, even at f/2.8. I see in comparisons w/ the Canon 70-200 f/2.8 the Sigma looks sharper at f/2.8 thoughout the zoom range. See comparison - http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=242&Camera=9&Sample=0& FLI=1&API=0&LensComp=469&CameraComp=45 3&SampleComp=0&FLIComp=1&APIComp=0

I used it for a wedding w/ good results but I find now using it for some more detailed photos it's having a few issues. I had a lighting setup configured for some product type shots consisting of a softbox nearly overhead, each side of table the product was placed on were white matte reflectors and a softbox on other side of soft box but lower to reduce any shadows. I shot some cooking ingredients - garlic, basil leaves, shlots - and they looked quite nice. However, I also had a black bowl filled with a couple more garlic cloves. In the shots on the rim of the bowl, ever so slight is yellow fringe on part of the circle. I know this will cause rejection for sure at istock. I shot w/ sigma at f/11 to f/13 at 1/125, iso 100. I also shot a glass bottle w/ olive oil, set on a mirror to give a real nice look of full bottle plus reflection, isolated w/ white. Here is where I really got annoyed. The metal dispenser at top of bottle (it's refillable, not the bottle the olive oil comes in) has too much purple/blue and there is RED all around the metal. Ironically I had just started using ACR for converting raw images and I noticed on the lens fix section you can fix red/cyan in chromatic aberration. I haven't really noticed red before. The metal top had both red and blue anda black dish isolation done seperately had a red ring around top of bowl. Each were shot at around 100mm.I shot the isolations at f/16 & f/22 to get the whole thing in focus. One advantage of the sigma was the "macro" capabilities. I am very disappointed in the results. In the end I reshot w/ ef 85 f/1.8 at f/16 for bottle and NO blue or red. I am a big fan of primes but it's nice to have one zoom in the bag. I have photographed my sigma lens and it may have togo up for sale. I'd love to see if the chromatic aberrations would be found in a canon zoom either the f/2.8 or f/4 version using the same lighting and materials. I'm guessing probably not. Either way I've had a few rejected w/ sigma 70-200 for chromatic aberrations that I didn't really see (though accepted by other stock sites). Basically I need a lens w/ little chroma as stock is insanely anal about it as I'm sure most of you know.

How is your experience w/ your canon zoom concerning chroma? Would my lighting setup cause chromatic aberrations in most zooms? Any help is appreciated. I have my sigma already in its bag getting ready for sale. So sad, it was almost a perfect compromise zoom to canon.