Canon 70-200 f2.8L IS (version 1) vs Sigma 70-200 f2.8 OS

[killswitch]

So there! Both have the Image Stabilization (Optical Stabilization or OS for Sigma). So the mark 1 version from Canon vs the Sigma's OS version. How is the sharpness and contrast from Sigma 70-200 f2.8 OS compared to the Canon 70-200 f2.8 IS version one. Is the difference in terms of sharpness and contrast huge or noticeable? AF performance of Sigma I hear is more or less on par with the Canon version, but please correct me if I am wrong. Also, can you AFMA Sigma or other 3rd part lenses on a 5DII/III ? Lastly, if I want to add focal length multiplier which teleconverters would be great for the Sigma glass on the bodies mentioned above. Kenko? Thanks.

[enraginangel]

I shot a wedding a couple a weeks ago with my Sigma 70-200mm OS for the first time and I had like 90% keepers. It really is a great lens. Yes, AFMA works and yes, TCs work. However, lens profile autocorrection within the 5D Mark III will not work, but you can still do that in Lightroom.

[killswitch]

I shot a wedding a couple a weeks ago with my Sigma 70-200mm OS for the first time and I had like 90% keepers. It really is a great lens. Yes, AFMA works and yes, TCs work. However, lens profile autocorrection within the 5D Mark III will not work, but you can still do that in Lightroom.

Cool, I was scouring the net to see what's the difference in sharpness. So far I found center sharpness is great, but the corners/edges tend to be soft. Have you felt this in your images, or are they just overstated. Personally for me as long as its not too obvious I guess its fine.