Greetings all, new here obviously, as numerous google searches did not help me find an answer, so in hopes you all do :thumbup: Here's the dilemma, I just got in the mail today the Sigma 17-70 OS lens for my Canon XTi. Right off the bat after installing the new lens, i noticed now that when i turn off my camera : 1.) Takes about a 3-4sec lag time before the green LED indicator turns off ( almost instant with the kit lens ) 2.) The camera makes like a "thump" sound as its turning off. ( never heard it before with kit lens ). Im not sure if its coming from the body or the lens.. 3.) The "sensor cleaning" icon sometime shows and sometimes doesn't, after turning off the camera. Can someone shed some light into this? thanks!