Please help me troubleshoot - I'm having an issue with my 70-200 f/2.8 lens

[Blue_In_AK]

For some reason my Canon 70-200 is suddenly being very temperamental about shooting at 70 mm on autofocus. When I depress the shutter halfway the little green light down in the corner flashes and then I can't depress the shutter the rest of the way to take the shot, as if I'm too close to my subject, but I'm not. If I move up to 100 mm or above it works fine. It also seems to work okay on zone manual or 19-point autofocus, but not so much on the single point autofocus, although sometimes it does and sometimes it doesn't. It's making me crazy.

Any clues?


I know it's the lens and not the camera because it's doing it on both the 7D and the 1Ds.

[Major Nikon]

1. You might try cleaning the contacts with a q-tip and some rubbing alcohol

[Blue_In_AK]

2. Thanks.

We're in Fairbanks, but I'll try that when I get home. It might be something funky that got in there in Nome when I was going in and out from the cold. I tried to be careful, but it was pretty hectic up there.