My winter wildlife photography tours and workshops put us in locations with lots of snow on the ground, which presents a new issue for most people – how to get good exposure without continuously messing around with exposure compensation.
You have to tell the camera to brighten your images by up to two stops of exposure to make whites white, because the meter in your camera wants everything to be a mid-tone gray.
For example, here is a photograph of one of our main subjects, the Japanese Red-Crowned Crane (above, left). It’s a predominantly white bird on a snowy white background. For a shot like this if I put the camera in Aperture Priority mode with the aperture set to f/8 for example, the camera would tell me that the shutter speed should be about 1/2000 of a second, which would result in a photo like the under-exposed dark version (above, right).
To avoid under-exposing images like this, one thing you can do is to dial-in +2 stops of exposure compensation in Aperture Priority mode. This would result in a new shutter speed of 1/500 of a second at the same aperture, and a beautifully white image.
There is one fundamental problem with this method though, and this is what most people fail to understand until they’ve missed enough shots for them to take my advice seriously. The moment your subject moves away from their white background, the exposure with +2 stops of exposure compensation is no longer valid.
To prove my point during a recent tour, I switched to Aperture Priority with auto-ISO and photographed this Whooper swan on the snow with +2 stops of exposure compensation dialed in. This gave me a perfectly white bird with perfectly white snow, as we’d expect.
Then, just moments later, I photographed a flock of Whooper swans flying into the same location, this time with a darker background, which fooled the camera into increasing my exposure and the result was this totally over-exposed photograph.
To avoid this, when photographing wildlife in the snow, the best course of action is to lock your exposure down (using Manual) so that when the opportunity to photograph something with a darker background arises, the exposure doesn’t shift, and the subject and the snow remains perfectly exposed, as in this example.
The downside of this method is that you do have to continually check your exposure, especially on a day with patchy cloud for example. Because you’ve locked down your exposure totally, you are responsible for noticing when it gets a bit brighter or darker, and updating your camera settings.
In my experience though, although you sometimes have to tweak the exposure in post-processing, you still return home with many more usable shots, as opposed to the above example with the flock of supernova swans, which is a firm candidate for deletion.
Settings Your Exposure for White
To set my exposure I usually just fill the frame with snow, and adjust the settings in Manual mode, until I see the caret on the camera’s meter indicate that the exposure is now at +2 stops for overcast snow or +1 1/3 stops for brightly lit snow.
How you achieve your exposure depends on your subject. Personally, I usually start with the aperture, as that controls depth-of-field, and I want to select that based on how much of the subject or scene I want to be sharp, and how much of it I want to be nice blurry out of focus bokeh.
Then I select the shutter speed, based on my focal length and how much I expect my subject to move. The rule of thumb for the slowest shutter speed you can use without the risk of introducing camera shake, is to use the focal length as the denominator of the fraction in your shutter speed. For example if you are shooting with a 200mm lens, the slowest shutter speed you can safely shoot hand-held is 1/200 of a second.
Of course, image stabilization or vibration reduction in the lens can help you to go slower, but you also have to consider subject movement with wildlife. To freeze a large bird in flight you need at least 1/500 of a second, but ideally 1/1000 or higher if possible.
These are, of course, general guidelines. You may decide to slow down the shutter speed and pan with your subject to use the blur of the wing movement artistically as in this example, but that’s the subject for another article.
Once I’ve decided the aperture and shutter speed based on the subject and any artistic decisions I might make, the last setting that I usually change as I lock in on my manual exposure is the ISO. Once the caret reaches +2 on the camera’s meter scale, I make a test shot, and check the histogram.
For a photograph of a field of snow, or a white bird on a white background, most of the data in the histogram should be almost touching the right shoulder of the histogram. This means the image data captured is almost pure white, as it should be. If the data is in the middle of the histogram, the whites will be gray. This is what the camera would do automatically without our help.
Also remember to turn on your highlight alert or highlight warnings in your camera’s settings, commonly called “the blinkies”, as these will alert you to any areas of your image that you might be over-exposing. It’s okay to over-expose a few specular highlights, but try not to over-expose large areas of your image, especially on your main subject, or the detail in those areas will be lost, and cannot be recovered on a computer later.
One of the other nice things about photographing birds over snow is that the light from the snow reflects up onto the underside of the birds in flight, as in this example. This means that you really don’t have to worry about where the bird is once you have locked your exposure down in Manual mode.
The subject can be on white background, a dark background, or a blue sky, and your exposure will be spot on, leaving you free to concentrate on focusing and composition, instead of frantically trying to adjust your exposure compensation as the action unfolds.
The post Why Manual Exposure is Better for Winter Wildlife Photography? by Martin Bailey appeared first on Digital Photography School.
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