I just got home from a long wedding.
During the wedding, suddenly my 16-35mm focus ring was stuck. It would only move maybe 1 mm only. Auto focus is still working fine. Zoom is also fine.
After trouble shooting for a few minutes, I realize that the focus ring worked after I hold the camera upside down and start moving the focus ring again. But after I hold it right side up, the focus ring was stuck again.
After a couple more minutes of trouble shooting, I can feel a small bump under the rubber focus ring. Then I figured out that it must be something loose inside.
I manage to lift the rubber focus ring, and voila a loose screw.
Now I'm home and manage to tighten the screw.
My question is, How important is this crew? Does it affect the focus? I mean, should I bring my camera to Canon Service Center to fix it instead of fixing it myself (over tighten maybe)?
FYI: I noticed that there are 2 screws next to each other, 1 with a white plastic ring and the other without. The one that is loose in my lens is the one without the white ring.