OK, that all sounds plausible. By the way, you do know you can impart this information without telling me I am an idiot for simply switching off my AC in every single reply, don't you? Anyway, as I said right from the get-go I had figured out this was something to do with misting even if the pattern wasn't very consistent. I shall endeavour to leave my AC on now that it is truly cold and damp and see if things settle down. What I haven't heard from anyone yet is something like "Yeah, mine does that if you don't leave the AC on all the time" or "Mine has never done that and I do/don't leave the AC on)." @rfo65: That's interesting information, and what I would expect, really. It really shouldn't rely on the cabin conditions to make sure that the screen in front of the camera is clear.