Matt Friedman

It's certainly a Hoya CPL. It briefly crossed my mind that a linear polarizer might interfere with the focusing sensor, but that isn't the case. Besides, it won't focus with the filter removed. The more I think about it, the more I think that I might have inadvertently jarred whatever linkage there is in the focusing mechanism when I initially had trouble with the filter. I didn't force anything, but I wonder if something got knocked out of place. Does anyone know if this might be serviceable (I'm fairly handy)?

Okay... I have a problem with my AF 24-85mm f/3.5-4.5. It has stopped auto-focusing. The manual focus works fine, but when I have it in autofocus, it whirrs, but does not focus. For background: I had it on a Maxxum XTSi, when I went out to shoot some early spring shots in the local state park when the sun came out. I did not drop or knock it in any way, and the switch back from AF to MF seemed perfectly fine. The problem arose when I put on a CPL filter. It did not want to sit on the threads, but eventually screwed-in just fine. But then, the camera would not autofocus. I removed the filter, and it still would not autofocus. My 70-210 beercan works perfectly, though. So the problem is with the 24-85 and not the body. Any ideas? Did I somehow damage the focusing mechanism when I put on the filter?