Given that rain, or any type of sky water, is about as free of impurities as any on earth (unless scouring an exceptionally dirty atmosphere), I can't think why there would be any marks if left to dry. I have carefully, and perhaps unnecessarily, blotted large drops on occasion, but normally let rain, mist, snow, etc. dry on its own without evidence. When shooting in mist or rain, I sometimes use a clear filter (warming, UV) to protect the lens, and have likewise never seen any evidence of unblotted drying marks on the filters. Last summer, my unprotected LX5 became wetted during an unplanned dunking in "clear" river water. I took the battery and memory card out and left it on a rock to dry overnight. The next day it was, and remains, in perfect working order, including its unblemished lens.
Last edited by ROL; 12-07-2012 at 12:24 PM. Click to view previous post history.