Broken 70-200 f4/L IS
Two weeks ago I returned from a month-long vaction in New Zealand - I'm still reviewing and processing those images. Among the lenses that I brought along was my EF 70-200 f/4L IS - it worked flawlessly on the trip.
Last weekend, I brought the same lens along on a short hike. Through the viewfinder, I could never get a sharp image - it was especially soft in the corners. At home, reviewing the images on the computer monitor confirmed that there was a problem. Images taken with my other lens showed no problems. (I was particularly bummed since I saw, and photographed, 3 different bobcats on the hike.)
I tested and confirmed that my beloved 70-200 had a problem. The IS mechanism works, as does the AF mechanism, but it produces only a "lens baby" effect. When I rocked the lens forward and back, I could hear something loose inside.
Monday, I sent it off to Canon in Irvine, California, for an out-of-warranty repair. They received it today and I now await their diagnosis.