Simple rules of thumb for exposure compensation when photographing snow using colour negative film such as Kodak Ektar 100 or Portra 160, 400, 800 or any other CN for that matter.
When you meter in the snow, you can almost be sure that your cameras centre weighted average metering system will underexpose as it sees the world as an average 18% shade of grey. So you will need to compensate for this by adding in some additional stops of exposure. Here are some rules of thumb that you can use in different lighting conditions to help with this:
- Snow with a clear sunny sky then give +2 to + 3 compensation*
- Snow with a lightly overcast sky then give +1 to +2 compensation
- Snow with a heavily overcast sky or in open shade then give +2/3 to +1 compensation
* top tip: if you using aperture priority mode on your camera and your exposure compensation dial only goes to +2 as most do and you think you may want +3 on a clear sunny day for with a bright blue sky, meter directly from the sky instead and lock in that exposure to make your photo.
Now an example, if your camera's centre weighted average metering system shows 1/800 at f5.6 for a snowy scene with Portra 400 on a dull overcast day, then dial in +1 stops of compensation to slow the shutter speed down to 1/400 and all should be good.