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What is Exposure Compensation?
Exposure compensation is a feature available on almost all cameras. It allows us to fine-tune the brightness of our photos, to make them darker or lighter, depending on our subject and our vision for the photo.
When would you use exposure compensation?
Do a simple experiment in either Program (P), Aperture Priority (A/Av), or Shutter Priority (S/Tv) mode.
Get a white piece of paper and take a picture of it – make it fill the entire frame of the camera. No flash.
Do the same with something that’s almost completely black, like the back of a large picture frame. Again, take a picture of it, no flash, and make it fill the entire camera frame.
Now go to your Playback mode and compare the two images. They’re close to the same tone, or shade, right?
A bright white object and a dark black object will be almost the same shade. That’s not how they look in reality!
The camera’s autoexposure will always want to expose your scene to “middle gray” – it’s the camera’s recommended brightness for your picture.
Depending on how you’re metering the scene (spot, evaluative, partial, etc – see your manual), the camera wants to set the exposure to be a tone halfway between black and white.
That’s just how cameras are because sometimes the tones in the scene average out to this mid-gray.
This is why you use exposure compensation. You need to compensate the exposure by telling your camera how bright or dark your scene really is. Remember, the camera isn’t smart enough to know what you’re photographing.
When taking a picture of that bright white piece of paper, or snow, or clouds, we need to tell the camera that our scene is really brighter than gray.
Taking a picture of that black picture frame, or asphalt, or a night scene, we need to tell the camera that our scene is really darker than gray.
That’s the key to understanding exposure compensation – how dark or bright is your scene supposed to be?
Setting exposure compensation
Somewhere on your camera is an exposure compensation dial or button, usually marked with the +/- icon. Refer to your manual. It may be referred to as EV Compensation as well.
Exposure Compensation is typically unavailable in AUTO modes; it will only work in the following modes:
- Program (P): The camera selects the shutter speed and aperture, but you can control the brightness with Exposure Compensation (EC).
- Aperture Priority (A/Av): You select the aperture and the camera selects the shutter speed, you control brightness with EC.
- Shutter Priority (S/Tv): You select the shutter speed and the camera selects the aperture, you control brightness with EC.
In addition to the dial/button, there’s also a metering scale on your LCD or in your viewfinder. The scales are usually divided into small tick marks and large tick marks, or numbers. Each large tick mark or number is one “stop” of light while the smaller marks can be set to 1/3 or 1/2 increments.
The positive and negative sides can be set to your preference and different manufacturers have different defaults, but moving towards the “+” makes the image brighter while moving the cursor towards the “-” makes it darker.
Exposure compensation Rules of Thumb
There are some generalizations to start, depending on your subject. Again, these are generalizations – they could be different depending on the lighting and reflectance of your subject. But they’re a good place to start, and you can adjust your exposure compensation from there.
- A blue sky at mid-day is generally the same reflectance as mid-gray, so set it to zero. Same with photos at dusk or dawn.
- Clouds and bright snow in daylight, +2.
- Asphalt, -2.
- Green vegetation or forests, -2/3 or -1.
- Human faces: +1 for pale Caucasians, -1 to -2 for darker Africans.
Look at the example below. The top image is letting the camera think for you. The snow appears gray instead of white. The bottom image is set to +1.3, making the snow look like real snow!
There is no one correct method of how to use exposure compensation. It all depends on your vision for the photograph.
Go ahead and intentionally underexpose for silhouetting or overexpose when a “washed out” look may be appropriate.
It may help to read my post about the Zone System for digital photography to further understand exposure compensation.
And if you’re using a mirrorless camera, you have the real-time histogram in your display as another tool to help you with exposure compensation.
Do you have anything to add?