CONDENSATIONWhen you take a cold camera into a warmer environment (as when going indoors after a shoot) or a warm camera into a colder environment (as when leaving your home or car with the camera), condensation likely will form on—and inside—the camera and lens. A good way to avoid this is to seal the camera and lenses in your camera bag, or a small plastic resealable bag with the air squeezed out, then allow them to adjust to the ambient temperature before opening the bag.
Don't exhale as you bring the camera up to your eye—your breath will fog the viewfinder eyepiece, and it won't soon clear on its own. Keep a microfiber lens cleaning cloth handy to carefully wipe away the fogging. Don't breathe on a lens to clean it—your breath will freeze on the lens surface. Use a camel-hair brush, lens-cleaning tissue or microfiber cloth to clean the lens.
WEATHER-PROTECTED CAMERASGenerally, the pro DSLRs can handle harsh shooting conditions, including cold and rain. Lower-end DSLRs cannot and should be used with protection, such as an underwater housing, in wet conditions.
AF performance and drive rate can become sluggish in very cold conditions, as can LCD monitor response (a particular concern when operating in live-view mode). That's another reason to protect your camera tucked inside your coat or jacket except when shooting—to keep it warm and maintain maximum performance.
If you're going to shoot in extreme conditions, you may want to consult your camera manufacturer's nearest repair center about winterizing your gear. This essentially consists of replacing the lubricants with cold-weather ones (you then can't use the camera in "normal" conditions unless the procedure is reversed).
This is quite costly, however, and most DSLRs can be used safely in conditions colder than those specified in the instruction manual if proper precautions are taken. Canon's EOS-1D Mark IV has an operating range of 32º-113° F (0º-45° C), for example, and Nikon's D3S has a range of 32º-104° F (0º-40°C). While those are top pro models, many less expensive DSLRs have shot a lot of winter photos in cold temperatures. Just check your owner's manual to see what your camera can handle.
WEATHER PROOFCOMPACT CAMERAS
A new generation of such cameras features really rugged, shockproof models offering protection against water, dust and cold temperatures (down to 14° F/10° C). These cameras are great winter-weather shooting companions, although again, not as versatile as DSLRs and mirrorless, interchangeable-lens cameras. Canon, Fujifilm, Nikon, Olympus, Panasonic, Pentax and Sony all offer at least one compact camera with waterproofing. These cameras can be an affordable way to try photographing in inclement weather without risking your DSLR.