In Nature, cast shadows on snow, and, snow-covered areas in shade, tend to be blue or at least at the blue/blue violet end of the spectrum of daylight. But the highlights, the areas not in shade or covered by cast shadows ... are white. So why do both the highlights and shadows go so blue in many photographed snow scenes?
The answer ... it's a phenomenon related to camera light meters; in the development of metering systems, many, many, many images were recorded in order to determine what degree of brightness constituted an "average," acceptable level around which to calibrate the metering systems.
Ultimately, that "average" was determined to be what is referred to as "18% gray."
And what that means is the following:
White = 0% tone. Black = 100%. If you started with a can of white paint and began incrementally adding black paint, when the paint was 18% gray you'd be at the one your camera's meter would use to correctly expose what it "sees" when evaluating a scene.
But meters cannot think for themselves, so, when they "see" an exceptionally bright scene ... they meter so as to adjust the exposure to make it that 18% gray. Overly dark areas ... it will want those also to be 18% gray.
So, how do you, the photographer, keep the brights, bright and the darks, dark? I am about to tell you.
For snow scenes (with lots of bright areas) ... use your EXPOSURE COMPENSATION FEATURE and INTENTIONALLY OVER EXPOSE the shot to bring the brightness back from the gray (or from those muddy blue shadow/shaded areas).
In scenes where you fear the darkness of shadow areas will be cloudy rather than crisp ... do the opposite ... UNDER EXPOSE.
Do this incrementally ... take several shots of a scene you think is a potential winner. Overexpose by +1/3 f-stops, then +2/3, then 1 full f-stop ... experiment ... you'll get it and in time, reading such scenes will become second nature.
Go for it and share those winners with us.
© All Rights Reserved/Article and Images/A. Macarthur