Rob said:The main issue with taking pictures in extreme cold and altitude relate to the temperature.
At low temperatures your batteries will pack up. Sometimes completely, to the point of being unable to turn an electronic camera on. At mega cold temperatures, your shutter will stick.
Generally in my experience, most cameras will work in temperatures which you can tolerate, however the batteries won't. The work around is to carry two or more batteries, with the active one in the camera and the spares in an intimate and warm place (I'll leave you to think that up). Trouser pockets are pretty effective. A battery will only last until it gets cold, then it'll conk out and you then swap it with one of your warm spares.
Generally, old fashioned cameras are better at lasting extreme temperatures. Also generally, fully manual SLR cameras are better than digital. However, it's not very likely you'll have a choice in which camera to take, so keep those batteries warm whatever you are doing.
Avoid exposing your camera and lenses to sudden and large changes of temperature - at best you'll get condensation and at worst you'll risk permanent damage.