I picked up a used 85L (Mark I) at the local camera store here yesterday for $1200. Whenever the camera has been off for a while, when I turn it back on, the AF won't work. Not at all. Manual (by wire) doesn't work either. Then, magically, after about 5-10 minutes (of camera being on), it'll start working. After that, it doesn't fail. This problem only seems to be happening when I first turn the camera on after it's been off for a few hours.
I love this lens, and don't want to take it back because I'm afraid I won't get another deal like this. I'm even starting to rationalize: "Okay, no biggie...I'll just let the lens 'warm up' for a while before trying to shoot with it."
Any idea what's going on? The lens came with a 6 month warranty, so it's no problem to return it...I just don't want to