lovelifey: [Photography] Exposure Compensation: Everything You Need to Know

The post Exposure Compensation: Everything You Need to Know appeared first on Digital Photography School. It was authored by Jim Hamel.

exposure compensation: the essential guide

What is exposure compensation, and how can you use it to improve your exposure settings?

Exposure compensation allows you to take control of your camera’s exposure variables. With carefully applied compensation, you can brighten up an underexposed photo, darken an overexposed photo, and create shots full of stunning, beautiful detail.

Of course, exposure compensation does take some know-how, and that’s what I share in this article:

The simple techniques that will get you the perfect exposure every single time you hit the shutter button.

Let’s dive right in, starting with the basics:

What is exposure compensation?

Exposure compensation is your camera’s exposure override button; by dialing in exposure compensation, you take control of your photo’s exposure from your camera (to brighten or darken the image). Note that exposure compensation is generally referred to using thirds of a stop, like this: -1, -2/3, -1/3, 0, +1/3, +2/3, +1, and so on.

Now, under normal circumstances – assuming you have your camera set to Program mode, Aperture Priority mode, or Shutter Priority mode – your camera will automatically measure scene brightness (i.e., meter off the scene) and input its calculated exposure settings.

But here’s the problem:

While your camera often does a good job, it won’t always get the exposure right. I get into the specifics later on, but there are certain situations in which your camera’s meter will fail consistently. Fortunately, you can learn to anticipate incorrect exposure values, in which case you might dial in positive exposure compensation to brighten up the shot (e.g., +2/3) or negative exposure compensation to darken down the shot (e.g., -2/3).

When you add exposure compensation, your camera changes exposure variables (i.e., aperture, shutter speed, and ISO) to give you an adjusted brightness. So exposure compensation isn’t free; it affects your images as if you’d manually dialed in an aperture, shutter speed, or ISO adjustment. But it’s a useful way to nail your exposure when you need to shoot quickly, and it’s also helpful for photographers not yet ready to shoot in Manual mode.

When should you use exposure compensation?

Every now and again, your camera’s meter will fail you.

Camera manufacturers have determined that most scenes will average out to a middle gray tone, often referred to as 18% gray. And your camera uses this 18% gray as its exposure benchmark; it analyzes the scene, then sets the exposure to perfectly match that gray value.

Of course, not all scenes do average out to middle gray. Some situations are supposed to be brighter than middle gray, such as a snowy landscape. Unfortunately, upon encountering snow, your camera’s meter will assume that the white should be gray, and will therefore choose settings that underexpose the image, as in the shot on the left:

two snow scenes, one with exposure compensation and one without — A snowy scene frequently confuses your camera’s meter. The left-hand shot was taken at a normal exposure. The right-hand shot was taken after adding in a stop of exposure compensation (i.e., deliberate overexposure).

Another example is night photography, where genuinely dark scenes should appear dark. The camera’s meter won’t recognize this, however, and it will try to brighten up the picture, as you can see below:

night scenes, one with exposure compensation and one without

In both of the above examples, you can see the problems inherent in camera meters – but you can also see the power of exposure compensation. Since I knew the camera would underexpose the snow scene and overexpose the night scene, I dialed in a stop of positive and negative exposure compensation, respectively, and I got a perfect final result.

So when should you use exposure compensation?

Whenever your scene is significantly brighter or darker than middle gray. Small deviations from middle gray aren’t a big deal, as you can fix subtle exposure issues when post-processing – but at the very least, you should add exposure compensation to very dark and very bright scenes. Otherwise, your exposures will look shoddy, and you won’t always be able to recover the lost detail when editing.

Another reason you may want to use exposure compensation is that you simply don’t like the “correct” exposure. For instance, you may want to darken a scene to add some mood or drama, or brighten things up for a light, airy look. Photography is a highly subjective artistic endeavor, so if you want to deliberately under- or overexpose your scene, then by all means, go for it!

How to use exposure compensation: the step-by-step process

You know what exposure compensation is, but how do you use it? While the specifics will depend on your camera model, here’s a standard step-by-step method:

Step 1: Set your camera to Aperture Priority, Shutter Priority, or Program mode

First things first:

You can’t use exposure compensation if you’re shooting in Auto mode, nor can you use it when shooting in Manual. (In Auto mode, your camera selects the exposure and refuses to give up control; in Manual mode, you don’t need exposure compensation because you have complete control over all exposure variables.)

So you need to set your mode dial to Aperture Priority, Shutter Priority, or Program. Aperture Priority is the most popular mode of the three – it lets you set the lens aperture and ISO while the camera automatically calculates the shutter speed for a good exposure – but Shutter Priority mode, which lets you set the shutter speed and ISO (while the camera sets the aperture), is also useful.

I’d recommend you set your camera’s metering mode to Evaluative metering, also known as Matrix metering. This will tell your camera to analyze the entire scene as intelligently as possible (whereas other metering modes, such as spot metering, may throw off your exposure process).

Step 2: Evaluate the scene and determine any necessary exposure compensation

The hardest part of setting exposure compensation is determining how much compensation to use.

For very dark and very light scenes, you can safely add a stop or two of exposure compensation in the relevant direction (remember: you need to underexpose dark scenes and overexpose light scenes!).

But if you’re dealing with a scene featuring lots of tones, you can do a bit of experimentation. Dial in some exposure compensation (as discussed in the next step), take a shot, then review the image on the LCD. (On a mirrorless camera with an EVF, you can just look in the viewfinder before pressing the shutter button!) You might also check the camera’s histogram.

Ask yourself: Does the result look good? Or is it too dark (in need of positive exposure compensation) or too light (in need of negative exposure compensation)? Based on your evaluation, you can make changes to the exposure compensation value, then start again.

In fact, when you’re just starting out with exposure compensation, you’ll need to do a lot of test shots and adjustments. Over time, you’ll get faster, but in the beginning, it’s all about learning!

Step 3: Find your camera’s +/- button and dial in the necessary exposure compensation

Most cameras feature a little +/- button, which is designed specifically for exposure compensation:

So find the button and press it. As you do, turn the main dial of your camera right or left, which will reduce or boost the exposure compensation value. Each click of the dial will usually change exposure settings by a third of a stop.

Note that pretty much all mirrorless cameras and DSLRs feature some form of exposure compensation, so if you can’t find the button, don’t panic. Some cameras will have a second dial, like this, that adjusts the exposure compensation settings:

the wheel on some cameras that allows for exposure compensation — The exposure compensation dial, or wheel, lets you quickly change exposure values on the fly.

Step 4: Shoot and review

Once you’ve dialed in your exposure compensation, go ahead and take a shot. Then immediately review it on your LCD (and check your histogram, too).

If the image is well exposed, then that’s fantastic, and you can continue to take shots of the scene as long as the light doesn’t change.

If the image is poorly exposed, however, then you’ll need to make adjustments and try again.

Bear in mind that your camera will retain your exposure compensation value after you’ve taken a picture. Every shot will be a stop brighter or a stop darker (for example) until you set the exposure compensation back to zero, so after moving on to a new scene, make sure you reset your exposure compensation!

Exposure compensation and the exposure variables

As I mentioned earlier in this article, exposure compensation adjusts different exposure settings to create a brighter or darker result.

But which exposure variables does it adjust? Does it change the aperture? The shutter speed? Or the ISO?

It depends on the shooting mode you use.

In Aperture Priority mode, exposure compensation adjusts the shutter speed. You set the aperture and the ISO, while your camera sets a corresponding shutter speed; if you then dial in positive exposure compensation, your camera will choose a slower shutter speed, and if you dial in negative exposure compensation, your camera will choose a faster shutter speed. In other words, Aperture Priority exposure compensation gives you the ability to change the shutter speed (and the overall exposure value) without adjusting the aperture or ISO.
In Shutter Priority mode, exposure compensation changes the size of your aperture. It is basically the reverse of Aperture Priority mode: you set a shutter speed and an ISO, while the camera sets a corresponding aperture. If you dial in positive exposure compensation, your camera will choose a larger aperture, and if you dial in negative exposure compensation, your camera will choose a narrower aperture.
In Program mode, exposure compensation changes the shutter speed – at least on my cameras. You set the ISO, and your camera will set the aperture and shutter speed. Then, when you dial in positive exposure compensation, the shutter speed lengthens (and if you dial in negative exposure compensation, the shutter speed is reduced). That said, it’s possible that your camera responds differently, so check your manual (or experiment) to be sure.

camera LCD with settings — Here we see the back of my camera before and after applying one stop of exposure compensation. In the example on the left, the camera shows a normal exposure with a shutter speed of 1/500s. Because the camera is in Aperture Priority mode, as soon as I dial in -1 exposure compensation, the shutter speed is reduced by 1 stop to 1/1000s.

Pro tip: Try bracketing your exposures

Bracketing is the practice of capturing a slightly underexposed and a slightly overexposed photo for each scene.

The idea is to maximize your chances of getting the proper exposure, and it can be very helpful, especially when you’re dealing with complex scenes or an expansive dynamic range.

Using exposure compensation, you can manually dial in a stop of positive and negative exposure compensation after each “standard” shot – or you can enable your camera’s Auto Exposure Bracketing feature, which will automatically adjust the exposure after each shot.

Note that bracketing doesn’t just act as exposure insurance; it’s also helpful if you want to do high dynamic range processing, where you blend tones from several different exposures for a perfect result.

So if you’re shooting landscapes or other stationary subjects and you have the time, go ahead and bracket.