What should I pay attention to when shooting with Canon SLR camera in ultra-low temperature environment?

I am from Harbin, a 60-day user. Harbin is much colder in winter than Beijing, but we still shoot ice lanterns and the world of ice and snow at night. At the coldest time, the temperature is MINUS 40℃, and the lens will freeze occasionally when zooming, but I'll just slow down. At low temperature, the battery consumes quickly, so just prepare a factory one. . . Let me tell you a few experiences. Take out the memory card first, put it in your underwear pocket after shooting outdoors, and then you can enjoy the film when you come back. Don't turn on the camera after you enter the room in the camera bag, and turn it on the next day, so that the machine can naturally adapt to the temperature change, which is absolutely no problem. Instead, you can hold the machine in your arms and wrap it in a coat (down jacket) when shooting. In fact, the main purpose is to prevent the machine from suddenly frosting from the cold into the warm room. . . .