How to Handle Your Camera’s Metering in Snow
The snow has begun to fall here in the west, blanketing mountains in a carpet of white. When we photograph snow, we need to pay closer attention to the light metering in our cameras. Manufacturers have different terms for their in-camera meters. But all of them basically function the same. A typical in-camera camera meter (even in today’s digital cameras) takes an average reading of the light being reflected off of the scene in our viewfinders. By taking an average reading, the in-camera meter can then determine proper exposure based on the 3 reciprocal variables of ISO, shutter speed, and aperture.
The Limitations of In-Camera Metering
As I mentioned, our in-camera meter takes an average reading. This essentially means that the meter is reading the light, then averaging that light to be somewhere in the middle, and then giving you an average setting for exposure – something as between “light and dark” as you can get. So if we understand that our reading is averaged, components of our scene that are lighter or darker than average in real life probably need the brains of the photographer for proper exposure.
Have you ever photographed snow with your meter in auto mode only to realize after taking the photo the scene is significantly darker than what you witnessed with your own eyes?
This same scenario happens oppositely when photographing dark subjects. Scenes with a lot of black are typically rendered lighter than they appear to your eye. This happens because your camera averages the light between pure white and pure black to create what is often referred to as middle tone, middle gray, or even 18% Gray.
18% Gray and Metering
So what is 18% Gray? The 18% refers to the reflectance of the color gray that your light meter reads. However, unless you only shoot black and white subjects, or nothing but Star Wars Star Destroyers and Death Stars, 18% gray will typically mean very little to you. I personally feel that middle tone is the most accurate description of what our camera meters adjust for us. If you think of any color out there – blue, red, green, orange, etc. – there are light tones, dark tones, and middle tones of those colors.
Our cameras average scenes for the middle tones of ANY color. This why lighter-colored scenes come out dark and darker-colored scenes come out light if we make no other adjustment to our camera’s meter when photographing these types of scenes.
Snow happens to work out perfectly for the gray color scenario. So if middle gray is what our camera is averaging for, then white snow will look gray or muddy if we do not adjust the meter to intentionally overexpose or add light to our meter’s reading.
Metering Types in Most DSLRs
Most DSLRs have the ability to adjust the in-camera meter for size/sensitivity. The typical adjustments are Spot, Center-Weighted, and Evaluative/Matrix metering. Brands cue in their own names for the meter settings as well (for example, Sony sometimes uses “Pattern” to describe Evaluative), making it even more confusing. So let me try to simplify what the meter is doing when you adjust these settings. Also see my viewfinder photo for a graphical representation.
Spot Metering will only allow the meter to pick up a small fraction of your scene in regards to its reading. This is usually highlighted in your viewfinder by a small circle in the center of your viewfinder frame. If you want the most accurate meter reading possible, switch to spot mode and put the circle over the specific part of your scene that you want to meter for and adjust accordingly. In the film days, this was the only meter setting you could effectively use to get a proper reading when shooting high-contrast transparency films like Fuijchrome Velvia.
Center-Weighted Metering is typically highlighted in your viewfinder by a larger circle or a set of brackets further from viewfinder center. It essentially expands the area of your in-camera meter and averages what is in the larger circle.
Evaluative/Matrix Metering averages out the entire scene in your viewfinder. I can honestly say that I never used this metering mode during the film days and almost always use it with my digital cameras today. Let’s discuss why.
Today’s digital cameras do an amazing job of automatically compensating for reflected light in most situations. The algorithms built into our digital cameras are far superior to film cameras of yesterday. With simulated exposure in Live View and camera sensors that have significantly more dynamic range than film, nailing exposure in-camera is becoming less and less important for photographers.
However, there are a few scenarios where you will need apply what is called “exposure compensation”. One of those situations is photographing snow.
The first time that I set out to photograph skiing, I knew nothing about exposure compensation and the effect that a bright subject would have on my final scene. I left my camera meter dead center and EVERY photo (a whole brick of Fujichrome Velvia) from that day was black. Film had a lot less dynamic range and a smaller latitude for failure.
The second time that I went out, I overexposed my ski shots by 1 1/2 to 2 1/2 stops and came home with perfect exposures.
Enter the digital camera. Two things happened when digital arrived. First, you were able to look at an LCD to see what your photo looked liked. Second, digital sensors weren’t as demanding for proper exposure as film was.
Even though digital cameras have brought this exposure gap down, I still find that a little overexposure in snow helps a great deal. Instead of adding 1 1/2 to 2 1/2 stops, a single stop is typically sufficient. Messing up isn’t necessarily a deal breaker either.
You can fix underexposed RAW photos in post. If you forget to add some exposure to your snow photos, you can still fix the exposure in Lightroom without adding too much noise.
It is pretty simple to take a test shot and look at your histogram to judge your exposure. The key is to overexpose your photo to the point at which your histogram is just touching the highlight side, or the right side. A trick for remembering which side of the histogram is for blacks and which is for whites: say to yourself “black and white”. We always say “black and white” in that order, as in “black and white photography”. We write from left to right – your histogram matches this. Left side is “black” and right side is “white.
Another way to remember: have you ever heard the term “expose to the right”? By exposing your scene to the right, the camera sensor is actually picking up more of the colors of your scene. When I do this for snow photos, I typically don’t use “blinkies” or even really look at my photo on my LCD screen. This is because it may actually look overexposed. As long as you do not have a huge spike on the right side of your histogram, you can pull back your exposure in post.
RAW vs JPG
If you are shooting RAW files, you do not need to worry about white balance in the field. Set your camera to auto and go to town. Your photos will potentially have a blue cast as the light gets lower. You can easily adjust this later in Lightroom. If you are shooting JPG in the field, you are screwed. Kidding, but you do need to take an additional step. Set a custom white balance for the best JPG results in snow. With my Canon 1D X, I can point the camera directly at the snow for any scene, take a photo, then set a custom white point for that snow.
If you are shooting RAW and you shoot through a sunset or even during a snow storm, you will probably get a final photo that is too blue. To fix this low-light bluing effect, I grab the White Balance Selector tool in the Basic Panel of Lightroom. From there I click in various places on my photo to get a custom white balance that gives my photo a more appealing color tone. Simple and done.
When photographing snow, a little exposure compensation goes a long way. Blowing your exposure while shooting RAW is time salvageable with today’s sensors. Adding a little bit of overexposure to your in-camera’s meter reading will not only give your photo more color, it will also introduce less noise should you need to add even a bit more exposure in post. Shooting RAW instead of JPG in-camera will also make your life easier when choosing a white balance setting. With a RAW file you can just set it to auto and go.
The Most Important Metering Mode
I think Evaluative/Matrix metering is the best setting for getting my camera to expose snow properly with the least amount of effort. But it’s really important to know what the other modes do. Here is a quick visual representation of the different modes from the post 3 Major Graduation Shooting Tips: Metering, Exposure Compensation, and Focusing:
Go out and try photographing in the snow and discover some results of your own!