This was my second year in a row going to a pheasant farm with a friend and his dad for a Jan. hunt. It was 21F degrees, windy, and cloudy (with moments of sunshine.) I slapped the Sigma 70-200mm f2.8 on the k10d, charged up all 4 batteries, loaded up the pocket with 2gb cards and went out the door. I wasnt sure how my battery life would be in the cold so I shot jpegs just in case. Turns out I could've just shot RAW. We were out for about 2.5 hours and didnt even use one full battery, or one full card. I took 109 shots. I shot shutter priority to freeze action, Iso 400, shutter 1/400, apperture between f4.0-f11.0 depending on light. Everything worked great, no malfunctions, no dead batt., just freezing hands that missed a few action shots while trying to warm up. These are by no means the best shots I've ever taken but, the equipment worked flawlessly in the extreme cold. Just thought I would share. I posted a few shots here
https://www.pentaxforums.com/forums/post-your-photos/18821-pheasant-hunt-21f-degrees-out.html