I shared a house with a good friend who wintered in Antarctica for a year. It was actually 22 months as the supply ship could't get there due to the severe storms that year.
The Australian base he was at, was not the type the Americans have, it was a reasonably rough affair. I remember receiving a message that the ice was getting through the cracks and freezing most of the building except for one room during one very bad blizzard.
He took two fully manual cameras, Nikon FM2 with three lenses. His film stock was FP4+ and he had more problems with the lenses freezing up than he had with the camera. They didn't really freeze up, but they became very hard to turn the focusing mechanism.
Basically down to about -30C there wasn't any problem, below that the 105 Nikkor started to be a bit hard to move.
The film worked perfectly, the coldest I believe that he shot at, was around -45C plus there was a wind chill factor of whatever degrees.
I developed about 90% of his film upon his return, not one roll of film was damaged. He had to get his film developed upon his return as he dropped his developing tank and cracked it in half. They stuck it together, but he couldn't get the screw top to go on properly.
I myself have used HP5+ down to -26C with no adverse problems, there was a wind chill factor as it was howling on the mountain top, don't know really how cold it was, except to say the I had difficulty changing film with gloves on. Without gloves my fingers started to stick to the metal of the camera which was a Nikon F3HP.
Mick.