Looking for some insight regarding protecting my lens and camera during a upcoming cold weather shhot in Montana next March. I've watch the videos and already know about the power supply concern. My concern is that would it so cold out as to effect the lens from functioning? I'll be shooting with a 500 as well as 100 to 400 and a few smaller primes. I just returned from Monument Valley where it appeared the 500 stopped working after several hours in the cold of night (no focus no IS). Is there a "sock" or other outter garmet other than raingear? Or am I worried about nothing and just be prepared to work around the cold. I really don't see me standing out in the cold winter of Montana for the same period I was in Moument Valley were it only got down to the mid 30's. Yes, I am expecting much colder weather in Monument Valley. Any help all is welcome.