Lets face it. Light is king when it comes to photography. There are literally thousands of different ways we can manipulate the light using modifiers and such, but what about one of the most simplistic ways that is already built into the camera. The exposure compensation button. All makes have this, but why is it important to photographers. You paid a lot of money for a very sophisticated computer, so lets allow it to handle some of the heavy lifting. So, what is exposure compensation? Short answer, it allow you to override what the the default exposure that the camera views as the correct, by several stops up or down. Today’s modern cameras do a pretty good job of rendering a decent exposure, but what if you want more creative control? Your camera is making assumptions for the correct exposure based on the subject or scene but there may be times based on the lighting, you may want the outcome to be lighter or darker. Generally your camera is going to try an expose for 18% grey or the middle. Exposure compensation allows you to over-ride the camera’s exposure, by telling the camera to over-expose or under-expose the scene by up to two stops away from the middle grey that your camera is trying to achieve. Cameras typically support at least two stops of exposure compensation in each direction.
Now, having said all that, the question remains, should you use exposure compensation? I present two examples here of my morning alarm clock outside my window. The picture above is what the camera rendered as a correct exposure of the subject based on the lighting conditions which in this case was front lit. Certainly not a bad picture, but when I looked at the LCD on the back of the camera I had highlight warnings on some of the breast feathers. Now the question of EV compensation comes into play. Should I or shouldn’t I underexpose to recapture the lost information?
The second picture is underexposed by 2/3 EV and I actually prefer that for my style of photography. I prefer what the underexposing and blacks do for the picture. That does not make it right or wrong, it is just what I prefer for my photography. That is really what I tell people when they ask why I am using the EV compensation. It is about manipulating the light for your photographic style and creating a picture with passion that tells the story. Their are settings in the camera that will read the scene or subject differently which factors into the EV equation as well.
Metering Modes and Exposure
Choosing the best metering mode is important to consider too, because the metering mode determines how your camera will measure the scene being photographed, when determining the exposure.
The default evaluative / matrix metering mode will cause the camera to meter the entire frame to determine the exposure required. Spot metering, which causes the camera to use a much smaller portion of the frame (such as the face) to determine the exposure. So in summary, exposure compensation allows you to over-ride the exposure determined by the camera. This is particularly useful when photographing bright scenes that the camera might under-expose (snow / beach sand / etc), dark scenes that the camera might over-expose, or for bright backgrounds, where the camera may under-expose the foreground (rear-lit subjects).
A Word of Caution
Note that any exposure compensation setting will remain, even after powering the camera off. Be sure to check the exposure compensation setting each time you pull your camera out, to ensure you can reset any exposure compensation that may still be set.
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