Canon 814XL - Manual (Page 99)

(Ambient temperature)
In very cold places, if you take a camera into a
warm room coming back from the cold out­
side, drops of water adhere on the lens or the
viewfinder because of the abrupt temperature
change, so that good filming becomes im­
possible. Be careful about this.
In the light of considerable temperature
changes, please gradually adapt the camera to
the environment's temperature. A way to do
so is to put the camera inside a vinyl bag, seal
it up, and let it gradually adapt to the change
in temperature.