Have you ever tried to take a photograph of a snowy scene and later realized that your shot was underexposed, maybe with an overwhelming orange or blue hue, or just lacking a certain "something?" Frustratingly, and surprisingly, snow can be one of the trickiest environments in which to make a correct exposure. But, with a few tricks and techniques in mind, hopefully you'll be able to make easy work of these trying conditions.
It All Begins with the Light Meter
The culprit behind these wrong exposures is likely your light meter; but this light meter is also the solution to finding the correct exposure for snow. In simple terms, all light meters, whether they are in your camera or handheld meters, are designed to read what's called 18% gray, or medium gray. Anything you meter—that is, point your light meter at—will return you with the information that will expose that subject so it is rendered as medium gray. For most subjects, this is fine; green trees, yellow fields, and gray asphalt—they're all medium tones and will look relatively fine if exposed as a gray subject. But then consider that your meter is going to do the same if you're photographing something pitch black or, in the case of snow, stark white. Your light meter is telling you the correct exposure for the snow in order to render it as a medium gray, not a bright white.
Backing up a bit, maybe you learned this in your high school photography class or stumbled on it on a late-night deep dive on the photo forums of the web, but the easiest way to envision these principles is to refer to the Zone System. Formulated by Fred Archer and Ansel Adams, the Zone System is a technique to help determine the best exposure using a system of visualization and precise metering. While mostly applicable to large format film photography, aspects of this system can benefit digital photography, too, with the simple concepts of visualizing a scene to help determine how to use your light meter readings. Refer to Ansel Adam's The Negative for a much more detailed look at the Zone System, but some quick takeaways for snow shooting:
• The Zone System scale comprises 11 distinct tonal values, or Zones, ranging from Zone 0 that is pure black with no detail up to Zone X that is pure white with no detail. Each Zone is one stop brighter or darker than the next (e.g., Zone V is one stop brighter than Zone IV).
• Light meters measure at Zone V, or middle gray.
• Adams described Zone IX as "glaring snow," Zone VIII as "textured snow," Zone VII as "shadows in snow with acute side lighting," and Zone VI as "shadows on snow in sunlight."
• Depending on the lighting and type of snowy situation you are photographing, you can see that between 1 and 4 extra stops of exposure may be required.
How to Use a Light Meter
With the above in mind, you could boil it down to simply needing to overexpose a couple of stops, depending on the lighting conditions, when photographing large expanses of snow. Either do this manually or set the exposure compensation to +1-2 stops, bracket your exposures a bit with some additional over and under shots, and you should be set.
If you're looking for the greatest accuracy, there are some techniques to help get everything right in one shot, and to develop a greater understanding of what's going on with your exposures each time. Even though it's your light meter that is deceiving you when making the poor exposures, it's also the tool that can be relied on to help make correct exposures. Once you understand the meter's objectivity, and its inability to determine what color or tone a subject "should" be, then you can work more effectively.
A hypothetical example could be an image of a small barn in a snowy field, with bright blue skies. Assuming you are using your in-camera meter, and it's averaging the scene; this is a perfect recipe for underexposure because the snowy field and bright blue skies are subjects that are brighter than middle gray, and the darkness of the barn will not be enough to bring the meter's average to where it needs to be. The snow will be gray, the sky an intense cobalt, and the barn will likely be too dark to make out the desired details. Ways around falling into this trap include using a spot meter, using an incident meter, or working with the Zone System and either manual exposure or exposure compensation:
• A spot meter, whether the specific Spot mode in your camera or a handheld spot meter, is a specialized method or tool for metering that focuses on a narrow "spot" to take the light reading. Opposed to averaging meters that might measure the entire scene being photographed, a spot meter is perfect when there are anomalies in the scene, or dramatic lighting that you wish to preserve. In our hypothetical example above, you could use a spot meter to measure only the barn and set your exposure there, which will render the barn as a middle tone with the snow and sky brighter. Alternatively, you could take a spot reading of the snow and then overexpose a stop or two to place it in the correct Zone.
• An incident meter is another type of specialized meter but is one that only exists outside of a camera. Compared to how your in-camera meter works (measuring only reflected light), an incident meter measures the light that is falling on the subject. These types of handheld meters are distinguished by their translucent white semi-spheres and are used in such a way where you point the meter back toward the light source or toward the camera, rather than at the subject. This method inherently avoids the issue of underexposing snow since it is not being tricked by reflected light. The one drawback to an incident meter is that it works best when you are able to be right next to the subject you are photographing, making it tough for landscape shooting.
• Use manual settings or exposure compensation, in conjunction with the Zone System methods mentioned above, to make intelligent decisions about how you want the snow to appear in your shot. In the example above with the barn, you would take a metering of the scene and then overexpose depending on how the snow looks. If it's bright out, and you want to preserve this brightness but still hold onto some texture, you would maybe want to place the snow in Zone VIII. If your light meter reads 1/250 sec at f/16, you would then set your camera to either 1/30 second at f/16 or 1/250 second at f/5.6, depending on whether you need to preserve depth of field or keep the shutter speed higher. Alternatively, you could also adjust the ISO if increased noise isn't an issue.
Hopefully, this helps you wrap your head around the intricacies of getting a proper exposure in snowy conditions. It's also worth pointing out that the same concepts can be applied for those in beach or sandy climates, since sand and very light-colored dirt will react very similarly to snow. Let us know if you have any specific questions about how to meter and expose in the snow, or let us know your metering process, in the Comments section, below.