How To Use Exposure Compensation (And Why I Don’t Use It)
As you're browsing through your camera's manual – you know, the page with the line drawing of your camera that tells you what all these buttons are supposed to do – you have likely stumbled upon a feature referred to as Exposure Compensation. The purpose of this feature is to override your camera's built-in metering system to force it to over-expose or under-expose at your command. As artists, we have great use for any feature that gives us more control. Exposure Compensation can be pretty useful, but it isn't the only way to control your camera's meter. So in this article, I'm going to teach you how to use Exposure Compensation. And then I'm going to teach you about a different method.
Using Exposure Compensation
Inside our camera is a pretty powerful computer that can, among other things, evaluate a scene and the to determine the best exposure. It does so by balancing the tonal values within the photograph so that the average value is equal to the tonal value of 18% gray, which is the industry standard for metering. This number was realized in the early days of metering research where it was determined that the average photo, when properly exposed, would have an an average value of about 18% gray, and the rest is history. This is an important fact because your camera is ultimately trying to push your photo so that the average tones meet this standard. Most of the time, this is going to be good or close enough. But it's not ideal if you are shooting in extreme conditions. Suppose, for example, you're shooting on a winter day with snow everywhere. If you let your camera do all the work, that snow won't be white because your camera wants that photo to result in an average of 18% gray. The same is true in the inverse when your goal is for a low-key image. Using Exposure Compensation, you can tell the camera your intentions and purposely over-expose or under-expose the shot.
Using Exposure Compensation is fairly simple. Somewhere on your camera, you may have a button that has “+/-” on it (the location and appearance on my camera is shown here). You can use this button to increase or decrease the Exposure Value (EV), most often in 1/3rd stop increments. Its use differs slightly between brands, so check your manual (Don't see a button? You may need to go into the menus).
By increasing the EV, you are intentionally over-exposing (or making the photo lighter) the shot. A decrease in the EV is an intentional under-exposure (or a darkening of the photo). Most often, you'd be using Exposure Compensation to correct for a miscalculation on your camera's part. I again revert back to that snowy winter day: Your camera won't see enough darkness in the shot, so it will improperly under-expose the shot. Increasing the EV will bring the shot back into balance. But you can also use Exposure Compensation to exaggerate your exposure for artistic reasons.
An Alternative Option (My Preferred Method)
Exposure compensation is a great way to bend your camera's will to meet your desires. But it does have two limitations that are of concern:
- The EV will also control your built-in or intelligent flash by changing its brightness in addition to altering the camera's exposure triangle. This may sound reasonable; and it is if your goal is simply to illuminate the scene. But if you're trying to create dramatic lighting effects, exposure compensation is going to severely limit your creative control. Remember, flash behaves very differently at different apertures and shutter speeds.
- The EV is always locked to your camera's ideal settings, which could change rapidly as things change within your scene. Here's a scenario: You're shooting a series of family portraits, each with a different number of people or arrangement of the people within the photograph. If the light isn't changing (and in a controlled environment, it definitely isn't), there is no reason why the ideal exposure would change. But as different people with different colored suits change position, your camera will think it needs to change the settings. You can save yourself a lot of time in post if you can lock it down.
The solution in both cases is simply to use manual mode. And it is simple. Many people are intimidated by manual, but it's a lot simpler than you think. Now I'm not going to try and convince you that you should be shooting manual all of the time, because that's really not necessary. Under normal conditions, you can likely use Aperture Priority or Shutter Priority. But again, under normal conditions, you wouldn't have need for Exposure Compensation either. Manual is for shooting under extreme conditions.
When shooting in manual, it's not that different from shooting in a priority mode, you just have an additional step. If you were shooting in Aperture Priority, you would start by selecting the desired aperture and then your camera would select an appropriate shutter speed. In Manual, you would also need to select the shutter speed. But you're not going to be operating blind; your camera's Exposure Indicator – like the ones shown here – will aid you. Reading them is fairly simple. The longer line or the arrow at the middle is what your camera views as the ideal exposure. This is your target. If the indicator is showing bars on one side of this line, your shot will be over-exposed if the bars fall on the '+' side, underexposed if it falls on the '-' side. On most camera, each bar represents a 1/3rd stop, and there are often indicators for a full-stop of light. You simply change the aperture or shutter speed until the indicator moves into the right position.
So to compensate for extreme conditions, you simply adjust your settings so that the indicator falls in a position on one side of the center (zero) point. For example, we're back in that snowy scene and we want the snow to be white. We'll compensate by over-exposing by a full stop, or three bars shown on the '+' side of the indicator.
In theory, this acts no differently than using the Exposure Compensation button. Except you aren't giving up control, your exposure is locked down and you aren't going to frustrate yourself with self-altering settings while trying to get dramatic lighting. In the long run, you're going to save some frustration.
So now you know two ways to override your camera's meter in order to compensate for extreme conditions. While the Exposure Compensation method is the easier of the two methods, it does have its limitations. Manual mode alleviates these concerns, but it can be somewhat intimidating for young photographers. Experiment with both to find the method that works best for you. Regardless of which you choose, both methods will give you more control. But more importantly, correcting for exposure in-camera using either method will ultimately save you time in post-processing. Who isn't interested in that?