Had two of these; VERY BAD so far

Maybe I have been unlucky with this lens as I have had very poor results. Surprising really when I have read good things about it from other users.

I bought this lens ironically to replace a 17-35mm Sigma EX lens that was very soft. This lens boasted to be sharp and had won a few awards from camera magazines.

I used it on a friends wedding and had a horrendous shock when I looked at the images later. A huge number of them were out of focus! I was checking the camera back on the day but shooting in RAW didn't always afford me time to check all the images (due to the camera being slow to process) so I trusted the AF.

For about a week I tried numerous tests and tried to work out where the problem stemmed from. I soon found that the lens after locking on in af mode then seemed to slip it's focus when the photo was actually taken. I have ruled out the possibility of a fault with my camera after trying other lenses.

This lens is also appalling when it comes to the fringing effect of high contrast areas (white against black). The colour fringing makes the images look soft even when they are sharp (which isn't often!!)

The only thing good about this lens is it's minimum focal distance and it being F2.8 throughout it's focal range. Honestly though what good is a lens if it can't focus correctly?! Don't forget this is my third try with Sigma in this focal range (the 17-35 and two of this lens). I'm sending it back (again) and am going to go for a Pentax equivalent. My only success so far with Sigma has been my 70-200 F2.8. Other than that I’m going to steer well clear of Sigma!

Avoid it like the plague unless you don't spot soft images easily.