10 out of 10 points and recommendedGreat OS, pretty fast auto-focus, 98% accurate, good sharpness overall.Softness near edges at wide apertures.
I originally had the non-OS version and did not intend to buy the OS version assuming that the overall quality would be about the same except for the OS, which I thought I could live without.reviewed December 22nd, 2007 (purchased for $510)
However, when I saw the first samples posted by a user, I was near convinced and after I bought the lens and tried it out for a couple of days, I knew I had not made a mistake.
What struck from the samples were the superb performance of the OS and the fantastic zoom range with two shots he took (while in a moving bus) from 18mm to 200mm close-up with both very sharp.
Most of my photography is done on the move, indoors and outdoors, at close quarters and then zooming out to capture something in the distance. With the OS, let's say, of 100 blurred shots caused by hand shake, this number has now been reduced to 10 or even less.
My use of flash has dropped too and now instead of 800 or 1600 ISO, I can get good, sharp shots at 400 ISO indoors using natural lighting. I have been successful as low as 1/4 second at 200mm though the success rate is somewhere around 30% to 40%.
In the 5 months that I have used the Sigma, I have never had any problems with colour rendition from this lens and most times, they are clear and vibrant, particularly if I take off the UV filter and just rely on the lens hood for added protection.
I have never used any L lenses and my experience is limited to the original kit lens, the Sigma 28-200, 18-200 and then the Canon 50mm f1.8 II. The Sigma 18-200 OS outperforms the first three of these for focusing speed, accuracy, image quality and, of course, low shutter-speed photography with its excellent OS. It matches the Canon 50mm f1.8 II near the center but, of course, not near the edges or for distortion. It's focus is quieter than the Canon 50mm f1.8, faster and more accurate. I have had many more out-of-focus shots with the Canon 50mm than the Sigma.
I have tested 5 copies of this lens with one that seemed a tiny bit worse OS-wise but I wasn't absolutely sure as time was limited. I bought two - one for myself and one for my nephew living in Canada. He regularly updates me on the shots he has taken and posts in his online album. He's very happy with it and calls it his "trusty Sigma". A friend of his is so impressed with the lens, he will be buying one this Christmas on his holiday trip over here.
Having read a previous post here, I tried out DXO Optics Pro on my Sigma shots. There is some improvement but not to the point where the original shots would be considered not good or unacceptable. The most obvious improvements so far (as I have only used DXO for about a week) are the reduction of CA, distortion and exposure adjustment between light and shadow. For CA, you would have to inspect the edges of the shot at 100% to really see the difference. I cannot see any difference in colour as yet. Perhaps, I need to explore further. However, DXO is definitely a good piece of software to use with this lens and I will continue to use it.
If one isn't into professional photography but wants convenience, good overall image quality, lots of keepers from shooting in different lighting conditions, particularly on travel (as it has done for me), this is a good lens to have on the camera.