Exposing the Snow

Author: Bruce Taubert

I love photographing wildlife in the snow.  When it snows in Arizona I grab my gear and head to one of those places where the snow will stick for a few hours.  Even though I left the Midwest in part to escape the frigid winter weather I find myself drawn to Canada, Wisconsin, Yellowstone and the like when the snow fly’s.  Why, because wildlife images taken in the snow show a simplicity and drama that is difficult to achieve during the warmer months.  Imagine a red fox in the bright, fresh snow or a snowy owl flying through falling snow.  The subject stands out in stark contrast to the all-white background.


Unfortunately, the photographer cannot just pick up their camera, point at the subject, focus, and shoot.  Well, they can but without preplanning the image will not be of their liking.  Why, because all light meters are designed to provide the photographer with a well exposed image of a “neutral gray” subject-one that reflects about 18% of the light that strikes it.  When taking images of lighter than neutral gray subjects the light meter directs the camera to underexposed rendering a darker than desired photograph.  The opposite happens when taking a photo of a dark subject-the light meter directs the camera to gather too much light and the result is an overexposed image.


Most photographers know that the way to correct for the light meters ill-advised settings is to use the cameras exposure compensation dial to add light to bright subjects and to subtract light from dark subjects.  Let’s say the photographer has their camera set on aperture priority.  The scene has a lot of snow with a red fox filling about 25% of the frame.   To obtain an appropriate exposure, the photographer adds 2 stops of light.  Snap, a perfectly exposed image.  Next the photographer sneaks closer to the fox to the point where it fills 50% of the scene.  Snap, oh crap the image is overexposed.  The cameras light meter reads an overall darker scene, sets the parameters for the darker scene (slower shutter speed), and then adds the 2 stops of light.


The same problem arises when photographing a moving subject, for instance a flying snowy owl!  The photographer approaches the owl sitting on a mound of snow.  The photographer exposes perfectly for that particular scene-probably aperture priority at plus 2 1/2 stops of light.  Snow reflects more than 90% of the light so this is a good starting point.  The photographer snaps a practice frame, looks at histogram, and is very pleased with their image.  The snowy owl spots a prey item (food), takes off, fly’s in front of a dark barn, up to the blue sky, and eventually lands on the unsuspecting mouse.  From the time the snowy owl takes off the photographer maintains sharp focus (difficult at any time), and machine guns the camera at 10 frames per second. The smiling photographer looks through the images and finds several underexposed images, several overexposed images, and a few correctly exposed images.  The photographer believes the underexposed images can be saved in postprocessing but the overexposed ones are lost to the world of texture less pixels.


The same phenomenon happened to the snowy owl photographer as the fox photographer.  The amount of light reflecting from the snowy owl never changed but the overall/average brightness of the scene did change as the owl flew through one background to the next.   During the process of making their images the changing light meter reading caused the camera settings to change.


There are several methods the photographer can use to rectify the exposure issue.  Try setting the camera on spot metering.  That way the meter will do a better job of sending the correct directions to the camera.  Unfortunately, it is very difficult to keep the spot metering focus point/s on a moving subject.  Just keeping a flying bird focused and in the frame, is difficult enough.  The photographer might place the camera on P setting (this is for programmed not professional) and hope the camera can do a better job of estimating exposure.  P setting might help a little but most of the time the image will continue to suffer from a misguided exposure meter.


The only cure for the problem is to set the camera on M for manual operation and take control of your future.  On manual, the photographer sets the shutter speed and aperture.  The photographer can take as many images as they want in as many different situations as they want and the settings never change.  The light meter will continue to operate but it will have no effect on the settings.  Let’s go back to the fox and owl.  As long as the lighting conditions do not change the only challenge is to take a proper exposure of the SNOW.  Yes, the snow not the subject!  In snowy conditions, or any time there is white in the frame, if the photographer sets the manual settings to take a good exposure of the white ALL OTHER PARTS OF THE IMAGE WILL BE PROPERLY EXPOSED.


The process I use is to first set the aperture.  For most wildlife subjects, I only need a modicum of depth of field.  Normally, I set the value to around f/8.  Then I decide on the shutter speed I need.  For the relatively stationary fox anything more than 1/500 sec will work nicely.  For the flying owl, I need a higher value of say 1/2000 sec.  Next I set the ISO value within the constraints of my camera.  On my Canon 7D Mark II I try to stay as low as possible and below 800.  With my 5D Mark III I can go higher and with my 1DX Mark II I can go to 3200 and feel perfectly comfortable.  Next, I take an image of the snow.  If it is too dark I make the decision what to change.  For the fox, I can probably go down to a shutter speed is 1/125 and still hand hold the camera (with modern image stabilization).  Depending on what camera I am using I could increase the ISO or, maybe, take the aperture to f/5.6.  In dealing with the flying owl I want to make sure to keep the shutter speed high so I first change the ISO and aperture.  I keep taking images until I have just overexposed the snow.  My favorite tool for detecting an overexposed subject is the highlight alert-blinkies as I like to call them.  When I see the blinkies I know my snow is overexposed.  Then I change the settings until the snow no longer blinks and then, for safety purposes, take away 1/3 rd. more stops of light.  I know this is a lot to swallow but it is very easy to accomplish.


Now that my cameras settings are correct for the snow all my images will be properly exposed.  The darks will be dark, the mid tones correct, the whites bright, and my efforts rewarded.  Now, IF THE LIGHTING DOES NOT CHANGE life is good.  If the day is uniformly overcast, the sky cloudless, or any other scenario where the lighting stays the same these settings work better than anything I have tried.  But, nature being what it is, the lighting conditions will change and the photographer must react.  Either change the settings in Manual mode or try aperture priority and suffer through the pains of losing valuable images.  In my mind the small amount of time it takes to readjust the Manual settings is well worth the effort.


Bruce is an instructor with Arizona Highways Photo Workshops