was happy to ge this lens. i knew it would have to be calibrated, not a problem. but the problem was even after calibration this lens would just not focus properly. sigma gave me a new lens...same thing...they gave me another new lens, same thing. finally they gave me a 4TH LENS and the manual focus ring does not work. the distance ring was unbelieveably tight, and the focus ring would spin, but the scale would not move...go figure.
stay far away from this lens or expect repairs and calibrations. yes i said calibrationS. i even had a lens calibrated, took some shots with the tech beside me. i noticed the shots were getting worse and worse AFTER CALIBRATION. the tech and i went back in to check the calibration and IT WAS NOT EVEN ON THE SCALE.
this is the biggest problem, the lens is totally unreliable. i shoot a lot sports so i would notice this more than someone who casually uses this lens. maybe you'll be lucky and get good one, but take one look at the ratings and you'll see the old lens is a far better lens then the newer one. very very unreliable and inconsistent, if your shots are important and you shoot more quality than quantity, this lens will hurt you and this is not the lens for you.
it just seems to not be able to focus properly. manually it is fine, but i think sigma needs to take a look at their chips and whether they believe it or not, there is defintely an issue with this lens.