Backlit Subjects

Now that we understand the basic variables which determine exposure, let’s look at some circumstances under which your camera’s light meter might lead you astray.

The classic example involves a photo subject that is back lit. Even though this book is about nature photography, we’ll use an example from that most unnatural of photo fields: portraiture. You’re taking a photo of a friend with a bright sky in the background. A normal averaging meter will see all that bright sky, and try to make it gray. Your friend, who isn’t so bright, will wind up too dark.

You need to train your eyes to see situations like this; always examine the background of your photos with its brightness or darkness in mind.

Once you have identified a backlight situation, there are three ways you can deal with it. First, you can overexpose the image (relative to your meters’ recommendation) by one, or possibly even two stops, depending on how bright the sky is and how much of the frame it covers. This way, the sky will be very bright on the photo, but your friend will be properly exposed.

The second way yields similar results, but uses a more precise method. You move in close to your friend, so the camera sees only the person and not the sky. Then you manually set the exposure, so that the primary subject of the photo (the friend) is exposed correctly. Then, you back off, and shoot your friend.

If your camera has a built in spotmeter or a zoom lens, you can take the meter reading of your friend without getting close. But then, maybe you want to get close to your friend. After all, you only shoot the ones you love.

Dr. Garth’s Prescription for Improving your Photography #614:

Set the exposure so that the primary subject is exposed correctly; don’t let the background confuse your meter.

The third way to expose your backlit friend is to use fill flash. This way, both your friend and the sky can be properly exposed.

Check your camera’s manual to see if your model can do the fill flash thing. Fill flash is great for situations like this example, but I don’t use it much for nature photography; it doesn’t usually look “natural” in broad landscapes. Generally you can see an abrupt transition from the flash’s light to the natural light.

Other confusing lighting

Sometimes, an image is dominated by dark tones. An accurate rendition of such a scene might be considerably darker than the middle gray your camera meter prefers. Perhaps the image is a close up scene of dark green moss growing on a black rock. The camera’s meter will try to take all of these dark tones and make them a light gray, substantially changing the mood of the picture. We’ll need to underexpose (again, relative to the meter reading) in order to preserve the dark feeling.

When I’m faced with such a situation, I use a highly scientific method to determine the exposure: I guess. I’ll say to myself “this scene is pretty dark. I’ll need to underexpose it a smidge.” Then I’ll set the exposure 1/3 or 2/3 of a stop below the meter’s recommendation. While guessing is a fine and wonderful method, you may be yearning for something more precise. Try this: find a region in the planned image that you want to be dark, but not so dark that no detail shows in the final print. Move in so that this region fills the viewfinder. Set your exposure value two stops below the meter’s recommendation for this spot. Re-frame your shot, and press the shutter.

Images dominated by light tones pose a similar problem, only backwards. To accurately render a bright scene, such as a snowy landscape, you need to overexpose (relative to what your stupid ol’ meter says.) The methods for determining the degree of overexposure are similar, as well. There’s the Garthian Guess Method, and there’s the move in and meter off of a small region method. This time, choose a small region which is light, but you want to still show detail. Set the exposure two stops over the meter’s recommendation. Re-frame, and shoot.

Another time your light meter might mislead you is when there is a lot of sky in the photo. A daytime sky is nearly always a lot lighter than the ground. An averaging meter often selects a value that leaves shadows on the ground in deep dark murky blackness. We’ll need to overexpose, but by how much? In this type of situation, I pretty much always use the GGM. I’ve been working at it for long enough that my guesses are usually pretty close. You might try a version of the “move in close” method, or you can bracket your exposures.

Dr. Garth’s Prescription for Improving your Photography #816:

When you are in doubt about the best exposure, bracket your exposures; take two or three frames of the same scene with different exposure values.