Cameras and the Cold - How to keep your camera working
If someone were to think of two things that don't go together, they might think of toothpaste and orange juice or electronics and water, or cameras and winter. However, there are some things you can do to mitigate the affects of the cold on the camera so that the camera will last longer than you want to stay out there. I recently spent two hours in the dark on the frozen ice at Lake Louise in Alberta Canada shooting the stars at -20C and my camera was still rearing to go when I was ready to pack it all in.
The first and most obvious problem is that the cold drains the battery incredibly quickly. Unfortunately, there is no getting around that. To give yourself more time, the best thing to do is to take the battery out of your camera and keep it in an inside pocket in your jacket. That way, as long as you're warm, your battery should have a decent charge to it. While you are setting up your shot, just keep the battery in your jacket. When you are ready to shoot, then you take the battery out of your jacket and take the shot. If you are planning to recompose after your shot or something isn't perfect and you need to wait for a bit, make sure you take the battery out and keep it warm.
The other issue is not actually the cold weather, but rather the relatively quick change in temperature. What I mean is when driving in your car on a very cold day, generally you have the heater on so that the inside of the car is at a pleasant temperature. When you leave the car, however, the temperature drops significantly. Colder air holds less water, so as the air inside your camera cools down, the teenie tiny water droplets in the air inside your camera end up condensing on the nearest solid surface, which might very well be the circuit board inside your camera. For obvious reasons this is something you want to try and avoid.
Likewise, when you move from cold to a warmer environment, so when you get back inside your car for example. The reason the car windshield fogs up is because with our breath in such an enclosed space, the air inside the car quickly becomes a relatively humid environment and as water vapour cools, it condenses back into water. Since your camera is likely very cold after spending a couple of hours outside taking photos, water is likely to condense on the camera.
The best way to counter the last two issues is to take a couple of the large freezer Ziploc bags. When you are going to change from one environment to the other, put the camera in the Ziploc bag and pad it with some air from the environment that the camera is coming from. Then leave it in the bag for twenty minutes or so to give the air in the bag a chance to acclimatise to the air outside. Since the bag itself should be where the change in temperature occurs, the water should condense on the bag and not inside your camera. Neat, hey?