Have you ever admired a scene, then taken a photo of that scene, only to realize that the photo looks nothing like what’s in front of you? Maybe the image came out too dark or too bright, making it impossible for the image to reflect what your eyes are taking in.
This unfortunate phenomenon can be attributed to an incorrect exposure of the image. Cameras rely on light to capture and create images. The way a camera takes in and uses light for each photo is known as the image’s exposure.
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Images can be either correctly exposed, meaning the image looks like the real scene, underexposed or overexposed. Underexposed images will be too dark, and overexposed photos will be too bright. However, you can slightly under- or overexpose an image on purpose for stylistic reasons.
Learning how to work your camera and manipulate the settings that change your images’ exposure is what will set you ahead of novice photographers. Understanding how exposure works is the first step to fully grasping exposure compensation, giving you creative freedom in your photographic endeavors.
Exposure Compensation: What is it?
Cameras use three tools – ISO, shutter speed, and aperture – to control the amount of light and how it affects an image. Exposure is combining these three variables, which measures how light or dark an image appears when captured by your camera.
Exposure compensation is the manipulation of light in an image. ISO, shutter speed and aperture are the three features every camera uses to discern how the light is displayed in an image. When it comes to exposure compensation, these three features can each be manipulated separately while using a camera set to Manual mode.
The automatic mode of cameras is named as such because it automatically sets your ISO, aperture, and shutter speed to take the available light into account for the image you are making.
Automatic mode shoots for a perfect exposure every time – which means the exposure tick on your camera’s meter would hover right below zero, signifying that the image is “perfectly exposed,” according to your camera’s meter.
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Using other modes on your camera allows you to play with the exposure of your image, shown by the placement of the tick on your camera’s meter. Using exposure compensation will enable you to manipulate the photo even further.
If the tick on the camera’s meter is to the left of the zero, the image will be underexposed closer to the negative numbers. Underexposed images will come out dark, meaning there was not enough light used in the image’s exposure.
A tick to the camera’s meter’s right toward positive numbers means the image is overexposed and more light is being brought into the picture, creating a brighter exposure value.
Reading a camera’s meter is the only way to understand how your camera deals with light, based on the way you have set your exposure with the ISO, aperture, and/or shutter speed.
Since the exposure settings cannot change in automatic mode, there can be no exposure compensation when using your camera’s automatic mode.
Though you can essentially create your exposure in manual mode, exposure compensation comes into play when using the Program (P), Shutter Priority (S or Tv), or Aperture Priority mode (A or Av). Each of these modes has unique features that allow you to have creative freedom by manipulating your images’ exposure.
How You Can Use Exposure Compensation
Now that we’ve discussed what exposure compensation does to an image, we can talk about using it on the go.
The exposure compensation button is a small button with a +/- on it. The exposure compensation button’s exact location may vary, and high-end DSLR cameras may not have the button at all.
Instead, these models will feature an exposure compensation dial on the back of the camera body that usually goes from -3 to +3; the exposure compensation dial will be used the same way as the exposure compensation button.
As said above, exposure compensation is the manipulation of light in an image by changing one of the three variables in the exposure triangle.
Those three variables of exposure are:
- ISO
- Aperture
- Shutter Speed
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The exposure compensation button will alter one of the three variables, depending on which mode the camera is in. You can increase the exposure compensation by pushing the exposure compensation button to the left or decrease the exposure compensation by pressing or rolling the exposure compensation dial to the right.
Each of the modes listed above — Program, Shutter Priority, and Aperture Priority — are compatible with the exposure compensation button. That compensation button will alter the exposure by adjusting the ISO, aperture, or shutter speed, depending on which settings you’re using.
To understand precisely how you are changing the image, you should understand how the exposure variables affect a photograph. Understanding the exposure settings will help you know exactly what the exposure compensation button is doing in each of these modes.
Understanding ISO and Program Mode
ISO, an acronym for International Organization for Standardization, is essentially a numerical value of how sensitive your camera’s sensor is, given the surrounding light at that moment.
ISO values typically range from 100-6400 on most DSLR cameras. The lowest number will be least sensitive to light, meaning it should get used in the brightest settings. The highest numbers will be most sensitive, meaning the higher ISO values will attempt to bring out as much light as possible in a dark environment.
If it’s a bright and sunny day, you should opt to set your ISO around 100. But, if it’s the middle of the night, an ISO of 100 would make your picture practically pitch black. Higher ISOs in dark settings make the scene more visible, meaning that the photo is more lit up than it appears in person. High ISOs are also a way to avoid activating the flash for dark scenes.
Higher ISOs can also degrade the quality of an image. Often, when ISOs are extremely high, the photos come out grainy or “noisy.” To avoid that “noise,” you should compensate by raising your ISO only slightly, focusing more on manipulating another variable in the exposure triangle.
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Program Mode is essentially an ISO Priority mode. When you are shooting with this setting, your camera will automatically set the aperture and shutter speed, but you can customize the ISO to your liking. If you change the ISO using the exposure compensation button, the other exposure values will change automatically to keep the photo from being overexposed or underexposed.
You can see how the exposure compensation is working in real-time by watching the camera’s meter. As you lower your ISO to be closer to 100, you allow more light to come into the image.
Some of the best times to use Program mode are when:
- Your subject is coming out too dark or too light
- Your photos look grainy and noisy from high ISO values
- You’re shooting very bright or very dark scenes
- You’re having trouble focussing on your subject
Understanding Shutter Speed and Shutter Priority Mode
Shutter speed is the amount of time your camera’s shutter is open to expose light onto the camera sensor. These speeds range from 1/1000th of a second to multiple seconds.
Photos of sports or other moving activities usually get captured on at least 1/500 of a second or quicker. Longer speeds can be used in very dark environments to light up the scene or stylistic choices to capture movement.
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S mode will allow you to set the shutter speed while the camera sets an aperture and ISO automatically. Using the exposure compensation button to boost the shutter speed to a faster and smaller value will not only bring in less light, but it will also affect how quickly the photo gets taken. High-speed action can get captured without blur on smaller and faster speeds.
Using the exposure compensation button to lower the shutter speed to become slower will bring in more light. For the camera to keep the correct exposure value, it will likely bump up the ISO and widen the aperture. These automatic compensations will keep the same amount of light available for your image.
You should use Shutter Priority mode when:
- Photographing a sports game or other action-filled event with both fast- and slow-moving subjects
- Using long exposures to capture a night sky or other dark subject
- Photographing wildlife
Understanding Aperture and Aperture Priority Mode
Aperture, also sometimes referred to as F-stop, is the opening in your lens that light passes through when making an image.
When you’re using your camera in automatic settings, the aperture acts like an eyeball attempting to find the right exposure. Like the iris of an eye, your camera’s aperture automatically widens when there is less light available and shrinks when light is abundant.
Small aperture values, like f/1.4 or f/2.8, are technically much wider than larger values because they bring in the most light by opening the aperture lens the widest. Values of f/11 or f/14 are small, in comparison, because they are bringing in less light by being less open than other values.
Aperture also affects the focus of the photo. Wide apertures, like f/1.2, will have a small depth of field, which can create a blurred, bokeh effect in the background. Smaller apertures, like f/11, will bring everything in the frame into focus. Small apertures are better for landscape photos, while wider apertures are ideal for pictures with a purposefully blurry background.
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Using Av mode gives you the option of manipulating the aperture’s size to create the look you are after. The exposure compensation button, in this setting, will change the size of the aperture.
The camera will automatically complete the exposure triangle by providing an ISO and shutter speed to work with the aperture. The exposure compensation button will alter the photo’s look, but the camera will always push for a correct exposure by adjusting the other variables accordingly.
Some examples of when to use Aperture Priority mode are:
- When photographing landscapes
- When making portraits of people, especially in crowded areas
- When photographing in low lighting
When to Use Exposure Compensation
Creating an image as you see it in your head requires using exposure techniques and customizing your images’ exposure value to your liking. In some instances, scenes, as they appear in real life, will be impossible to capture without using exposure compensation somehow.
Mostly dark scenes, action-filled moments, and photos of things very close or very far away are examples of times to utilize exposure compensation. Though your camera is smart and can usually set the right exposure for general scenes, the camera can’t find the right exposure value every time. These instances are when exposure compensation comes into play.
Practicing exposure compensation in different modes will help you understand how light works in photography. Finding the correct exposure on your camera’s meter may be difficult, but photography is open to interpretation and customized to fit the user.
The exposure compensation button is an excellent way to learn more about how your camera is using light. Use exposure compensation as much as you can in your day-to-day life to become proficient as quickly as you can.
Just remember — all three parts of the exposure triangle must work together to create the image. Understanding one part of the triangle is useless if you do not understand the other parts, too.
Now, you’re just some practice time away from being a more knowledgeable, confident photographer!
