Well, I've used my Zorki 4 with Jupiter 9, 12 and 8 in down to -28 Celsius.
When I was skiing downhill i Sweden 3 years ago. -25 - -28 in the morning, -14 to -18 in the afternoon. Without my Zorki slung in a half "never-ready" over my head/shoulder, I would never had gotten any pictures of my middle son doing big slopes for the first time. The camera was outside my jacket, sometimes getting some snow on it. No problem.
He was adamant to go up to the highest hilltop regardless of temperature. Up there the -14 to -18 was even colder, thanks to 10-20 knots of wind. But clear sky and sun. Up there he was more quiet than ever, but skiing and wanting to go up again, and again, and again.
(Do I sound proud? 😱)
Not many digitals around then 🙂.
The biggest problem was the fragile film. Winding had to be done very carefully.