Seemed to run into a problem with my primary lens, and it is starting to concern me. I was out stalking a bird for about ten minutes, and when I went to auto-focus, the lens emitted a horribly loud screeching noise that scared the heck out of me and caused the bird to fly away. The lens did focus correctly, just made a noise, which cannot be good for it, and then continued working without making the noise. After a few days of being good, it just recently started making the noise all the time, but still focusing properly. I am just wondering if anyone else has had this problem. What is going on and what can be done?
Oh, and the lens is the Sigma 70-300 f/4-5.6 Macro Super II (non APO)
