I bought this lens new in 2011, it has not seen much use and should be in good condition. Suddenly it fails to autofocus. The problem is on and off unpredictably on different cameras. I have cleaned the contacts, but what seems to help sometimes is to turn the focusring 10-15 times. Or just leave the camera, take it up another time - suddenly the AF can work. When the AF works, there is no strange sound that indicate problems with the motor. Can the problem be caused by little use of the lens or corrotion in AF/M contacts og switch on the outside? This lens is common, so is there anyone in this forum that has an idea or experience with this problem?
