The Sigma 70-200 EX is not on par with the Canon 70-200L. I provided full size controlled comparison samples, above.

As you can see, the Sigma is quite yellow in color (almost all Sigma lenses suffer from yellow color), lower in contrast, very slow to focus (the Sigma is takes about three times longer to focus), built relatively lightly, has a busier bokeh, is 1/2 stop dimmer at f/2.8, is too soft wide open and substantially softer stopped down. It is cheaper, however, though I don't think Sigma's discount makes up for their lower quality.

Sorry, my experiences shooting with both differ from yours. I stand by my statement and my photos - IQ is virtually no difference. Focus speed in good light is no difference. Focus speed in low light, slight edge goes to Canon. But it's only very slight. But people can judge for themselves based on the photos I've posted. Every bit as good as what I can get out of the Canon.

SigmaSD9 wrote: I fail to see the merit of your argument, this is the Nikon site. I have not used the nikon 70-200, but a friend of mine used one extensively for outdoor sports (high school baseball) in daylight and under lights, and much prefers the Sigma.

JohnG wrote:

A few facts/observations from using both lens extensively side by side:

The Canon lens focuses in a little under 1/3rd the time under all conditions. Canon's USM motor is more powerful than Sigma's HSM motor.

The Canon L is much sharper wide open. The Sigma EX is too soft at f/2.8, it should carry an f/4 badge. Even Canon's f/4 version is sharper than the Sigma at f/4, plus it is less expensive.

The Canon L has a much heavier build

The Sigma EX's glass is noticably yellow cast, the Canon L is both more colorful and neutrally balanced.

Here is a controlled MLU f/5.6 test using SPP: