tips after the break
Generally if you are shooting in snowy conditions and you are using any auto settings such as
P, A( Av), S (Tv), or Auto (or if you are looking at your histogramme) you will want to add a
POSITIVE EV compensation
(the reason is that the sensor is looking at the situation and seeing a lot of white, thinking it is over exposing, it will decrease the shutterspeed (iefaster) or the aperture size
to try and keep everything more in the middle tones, but snow is meant to look white so you have to tell the camera to compensate and keep it at the right hand side of your histogramme)
Tip 1 (part B)
If you set your camera to a positive 2 exposure compensation, and you are using flash in a TTL setting, your flash will also be shooting at Positive 2 TTL. This will totally blow out the subject you are shooting.
You will have to dial in some Negative Flash Exposure Compensation in the flash menu settings to help over come this.
When moving from a cold location (such as outside) to a room temprature (such as inside) your camera lens will steam up. The sudden change in temp on the front glass element will cause condensation (which could give you a cool looking soft focus halo look to a portrait, but is not advisable) and steam up the eye piece as well. Give your camera and lens at least 20 minutes in each temprature location before trying to take any snaps.