Not a very nice day ,have just confirm that my Sigma 70-700 mm 4-5,6 DG ,camera lens give problems. The lens is used on a Canon D1100.
The problem is the Auto-focus ,sometimes it just don't work,it actually get stuck.The lens is about one year old and been used 30 hours.(3 year warranty)
After the initial "shock" try to do some research on the internet and saw the following interesting remarks.
-Sigma and Cannon is not that com-pliable(inter) as said in the marketing field.
-The focus problem is known to some users(?) and there is some models (lenses) that is recall by sigma and repair cost free.
The problem now is ,repair,give back(with a fight) OR buy a new one(not likely).
Want to limit my risk of a broken lens during that precious hours of a weekend or holiday.