The Final Word on Proper Snow Exposure
©1999-2011 Mike MacDonald
From gentle flurries that fall from the sky to endless fields of white, snow is the essence of winter's magic. Snow has the power to transform a lackluster landscape into a shimmering snowscape, the gray earth into a fairyland of white. Sadly, dramatic photographs are often ruined because the photographer did not know how to properly expose his camera's sensor.
What I am teaching here is covered in my Complete Exposure class through Creative Eye Workshops. But, what I'm teaching here is just one special case. To learn about how to properly expose EVERYTHING, not just snow, the course is essential.
To properly expose anything, we first need to talk about how a light meter works. Reflective light meterslike the one inside all modern camerasassume that the color of any subject you point it at is a middle-toned shade of that color, even if it isn't. If you point it at a red-winged blackbird, it thinks it's a red-winged graybird and it will turn out that way in your picture. If you point it at a magical white snowscape, it will end up as a dingy, gray landscape. However, you can accurately record these subjects by simply adjusting your camera to let in less light for the bird, and more light for the snow.
To take an accurate meter reading, your camera needs to have spot metering capability. Partial metering may work, too, but you need to be very careful. First, set the camera to Manual Exposure Mode ("M" on most cameras). To take a meter reading, look through the viewfinder and aim the spot at the point of the subject you wish to meter. Now, change the shutter speed and/or aperture such that the meter is centered at 0 (zero). Congratulations! You have just taken a spot meter reading. (NOTE: Your viewfinder may not actually show an outline of the spot (or partial) metering area, so consult your camera's user manual to give you an idea of how big it is.)
However, remember my example of the snow and the blackbird? Well, that was a lesson about your camera meter having certain limitations. So, it's up to you to make the proper corrections or "exposure compensations."
So, for snow, simply let in 2 stops more light. This means that, while you have the spot meter aimed squarely at the brightest patch of snow, change the shutter speed and/or aperture so that the meter reads +2.0 stops (instead of 0.0). Then recompose and take the picture. NOTE: IGNORE THE METER AFTER RECOMPOSING.
Though all of this may seem a bit tricky, metering a snow scene is actually extremely reliable and accurate, since the reflectance of snow is fairly predictable. Snow acts as one giant "white card" with a known value of 2-1/3 stops brighter than middle tone. This makes it easy to get an accurate light meter reading simply by spot metering that magical patch of white.
To guarantee the perfect exposure, it's helpful to bracket the exposure by only the slightest amountusually only 1/3-stop. There are really just two steps to perfect snow exposures:
Step 1: Study your snow scene and determine the brightest area of snow that must show detail.
Knowing what to meter is very important, so understand and practice this step. That's because there are times when a subject is so small in the frame that recording detail is not necessary. In Example 1, if you decided to record detail in the sunlit accents of snow on the tree branches, most of the snow in the scene will be sorely underexposed. In this case, it is essential to ignore these sunny highlights and expose only for the snow that fills the vast majority of the frame. This is a critical decision that you will need to make.
For snow scenes that are evenly lit (overcast or hazy days, open shade, or full sunlight), pick the snowy spot that seems to be the brightest. In situations where the snow is dappled with sunlight, select the brightest area of sunlit snow.
Step 2: Spot meter the area selected in Step 1 and increase exposure as follows. Sunny Snow: +2 stops. Cloudy Snow: +2 to +2.33 stops (bracket if you wish).
In evenly lit situations, this step is a snap. Just spot meter the snow and open up. However, it's sometimes hard to get a spot meter reading from a bright patch of snow in dappled light. If you're using a wide-angle lens, you're spot meter area will probably record both sunny and shady snow areas (see Example 2).
In this case, I've figured out a very slick way of indirectly metering the sunny snow. It starts by taking 2 meter readings in Manual Exposure Mode. First, move the spot meter to an area of snow that's completely shaded and balance the meter to zero. Now, carefully aim your spot meter at a 50/50 mix of sunny and shaded snow and note where the meter falls. If it says "+1.3," then turn the meter to the exact opposite or "-1.3" (stopping down 2.67 stops). Now, exposure compensate for the snow by adding 2 stops. Bracket by 1/3 stop and you should be fine.
EXAMPLE: You're working on a landscape that requires an aperture of f/16 to get enough depth of field. There are many trees with their shadows cast upon the snowy ground. But, because you are using a wide angle lens, you can't get a reading of the sunny snow without also including some shadowed snow. Set the camera to Manual Exposure mode and Spot Metering. Aim the spot meter at a patch of shady snow and balance the meter to zero. Let's say that it reads 1/30 second @ f/16. Next, aim the spot meter area at a patch of snow that is equally sunny and shady (the 50/50 patch). The straight edge of a tree shadow should provide the perfect dividing line. You see the meter move to +1.3. Now, while holding very steady on the 50/50 snow patch, change the shutter speed so that the meter moves to -1.3 (minus 1.3). It will now read 1/200 second @ f/16. Finally, open up 2 stops to compensate for the snow (dial meter to +0.67) and you get a final meter reading of the sunny area as 1/50 sec. @ f/16. Take the picture and bracket by 1/3-stop.
Get out there and practice. With digital photography, you should be able to immediately see if you're doing things correctly. Check the picture and also your histogram. In a snowy setting, there should be some bumps to the far right of the histogram, otherwise your shot is underexposed. But, again, you need to practice.
It's a great disappointment to photograph a magical winter landscape, to later find that you're pictures turned out badly. Now, when you find that sensational snowy scene in wondrous winter light, you can concentrate on your creativity and show others how enchanting winter really is.
Copyright 1999-2014Mike MacDonald Photography, Inc.
Copyright 1999-2014Mike MacDonald Photography, Inc.