A topic that comes up often on Trailspace is photography - what camera to get, posting pictures, photos with trip reports, photo contest, member albums, and so on. I am putting this in Backcountry, since Trailspace does not have an "Outdoor Photography" forum, and since it deals directly with backcountry winter photography (or maybe Climbing photography), but not about gear choice per se.
A commercial photo dealer, Ritz, which sends out huge amounts of emails once you get on their list, has started including "how to" articles. Now that winter is upon us, they posted an article on cold weather photography. Now, although I have bought some things from Ritz (mail order, internet, and hundreds of affiliated stores), this is by no means an endorsement. I prefer to deal with my local specialty photography shop, Keeble and Shuchat, just as I prefer to deal with my two remaining mountaineering shops.
Just a couple comments on the article and my personal cold weather "tips" -
Overall, the article has some good points to make. Things have changed drastically in the realm of photography, with film virtually disappearing (although digital cameras still have a way to go before matching the best quality film photographs, if you compare like formats - FX format to 35mm film, medium format digital to medium format film, etc). Certain of the precautions with film do not apply to digital cameras - the old bugaboo of static discharge streaks in subzero dry conditions, for one. However, condensation is a very strong consideration for digital electronics.
If you take a warm camera into cold conditions, condensation is not a problem. But bringing a cold camera back into a warm environment (even into your tent, sometimes) can get condensation inside the camera on the electronics. I find that putting the camera in a ziploc bag while still outdoors in the cold, then letting it warm slowly helps - the condensation forms on the outside of the bag rather than on the camera. Also, I generally put the now-cooled camera into a ziploc bag before stuffing it back into my parka to allow it to warm a bit - which prevents my sweat from condensing on or inside the camera.
What about shooting in wet-snow conditions? There are waterproof enclosures, such as GoPro supplies with their cameras, and plastic waterproof bags with a hard plastic viewing window, as well as "raincoats" for your camera (I have an Aquatech that I mostly use in rain situations, but have used in wet snow conditions). If you are using the hard plastic box type or soft plastic bag type enclosures where the camera is sealed against the outside world, be sure to allow plenty of warmup time before opening the enclosure in a warm, possibly more humid environment.
Batteries do lose power when cold, including lithium batteries. Lithiums do retain more of their power at colder temperatures than any other variety (including NiCd rechargeables). So keep spares inside your parka and inside ziploc bags. Something to note is that often a battery will appear to die because of the cold, only to revive when heated by carrying it inside your parka for an hour or so.
Note - some cameras and other electronic devices that use AA and AAA batteries do not work with Lithium AA and AAA batteries, due to the fact that the new Li have an initial voltage of about 1.8V, vs alkalines at 1.6V and NiCd rechargeables at 1.5 V. Barb's Canon A-series has overvoltage protection that shuts the camera down when it detects a higher voltage than about 1.65V, as do a couple of my GPSRs and some other electronic widgets we have.
But what about the need to change batteries or memory cards? If you have kept your spare batteries and memory cards inside your parka so they stay warm, you have no problem. You can change the batteries and memory cards, even though the camera may have become chilled. Put the used ones in a ziploc bag before moving them inside your parka. As noted above, the chilled batteries will sometimes recover a little as they warm up.
Then again, you can avoid changing memory cards by getting larger memory sizes. It takes a large number of photos to fill a 32GB card, even when shooting RAW 14-bit color depth images as I usually do (more than 1100 pictures). And you can now get SD and CF cards up to 128G (remember, SD cards come in SD, SDHC high capacity, and SDXC extreme capacity, so make sure your camera can use the higher capacity cards before buying them).
The most basic tip is, of course, keep yourself warm and dry. That includes your fingers and toes. Learn to use your camera WITH your gloves on.