Basic Photography 101: A Beginner’s Guide to Understanding Overexposure and Underexposure

Exposure is a measurement of how much light reaches the film or camera sensor when a picture is taken. The exposure translates into how bright or how dark the final photograph will be. The more the film or camera sensor is exposed to light, the brighter the image will be, and vice versa.

Overexposure is the result of too much light hitting the film or, in a digital camera, the sensor. Overexposed photos are too bright, have very little detail in their highlights, and appear washed out.

Underexposure is the result not enough light hitting the film strip or camera sensor. Underexposed photos are too dark, have very little detail in their shadows, and appear murky.

Exposure is a creative choice and there is no “correct” exposure for any one photograph. How much you expose a photo depends on what mood, emotion, and feeling you hope to convey in your work. Some photographers consider correct exposure to be a natural-looking photograph with balanced both highlights and shadows that don’t result in any lost details. Other photographers might deliberately overexpose or underexpose a photo to obscure unwanted details or convey a specific feeling or emotion.

Understanding these concepts will help you take better photos:

1. 1. Understand the exposure triangle. The exposure triangle explains how shutter speed, aperture, and ISO work together to take a photo with proper exposure. All three elements affect one another; if you adjust the shutter speed, it affects both the aperture and the ISO. Understanding how they work together will lead to more properly exposed photographs. Learn more about the exposure triangle in our complete guide here.
2. 2. Set a low ISO. The ISO number determines how sensitive your camera’s sensor is to light. If your ISO is too high, you could overexpose the image. Some guidelines to keep in mind: ISO 100 on a sunny day, ISO 400 on a cloudy day, ISO 800 when shooting indoors, and ISO 1600+ in extremely low-light settings. Learn more about ISO in our complete guide here.
3. 3. Set a medium-to-high aperture. The aperture is the opening that allows light to hit the sensor and changes the depth of field. Aperture is expressed in f-stops. If your f-stop is too low and your aperture is too wide, you could let in too much light and overexpose the image. Start with a medium aperture around f/8 and tinker from there. Learn more about aperture in our complete guide here.
4. 4. Set a medium to fast shutter speed. The shutter speed refers to how long the camera shutter is open while taking a picture. The longer your shutter is open, the higher the chance of overexposing the image. A shutter speed of 1/60 is a good place to start, and you can adjust from there. Learn more about shutter speed in our complete guide here.
5. 5. Use the light meter. A light meter measures the amount of light in a scene to help you determine the best exposure for an image. Most Canon, Nikon, and other DSLR cameras have a built-in light meter. You can buy your own light meter, which is generally more accurate and can test light from a variety of angles.
6. 6. Use exposure compensation. When you’re shooting in shutter priority mode or aperture priority mode, if part of the frame is very dark or very light, your camera may get confused. Rather than switching into manual mode, you can use the exposure compensation dial to override the camera settings. Turning the dial tells the camera to overexpose or underexpose the shot.
7. 7. Reference the histogram. In digital photography, a histogram is a bar graph that indicates how many pixels are captured ranging from pure black on one side to pure white on the other. Most digital cameras can show a histogram on the display: bars clustered toward pure black indicate an underexposed image; bars clustered toward pure white indicate an overexposed image.
8. 8. Use bracketing. Bracketing is the practice of taking two extra shots for every photograph: one with a +1 exposure value, and one with a -1 exposure value.

Underexposed and overexposed photographs are inevitable and happen to every photographer. You can adjust exposure and recover details in the over- and underexposed areas with editing software, like Adobe Photoshop or Lightroom. Try these techniques and see what works best for your photo:

1. 1. Move the exposure slider. Perhaps the simplest way to adjust the exposure, the exposure slider easily lets you add or take away brightness from the overall image. Drag it to the right to increase exposure or drag it to the left to decrease exposure.
2. 2. Move the white balance slider. The white balance slider specifically lets you adjust an image’s mid-tones. Drag it to the right to increase brightness or drag it to the left to decrease brightness.
3. 3. Move the highlights slider. As the name implies, the highlights slider lets you adjust the highlights, or brightest parts of your image. Drag it to the right to increase brightness or drag it to the left to decrease brightness in the highlights.
4. 4. Use a graduated filter. The graduated filter tool lets you add a darkness gradient to part of your photo. Select the overexposed area and adjust the settings to darken the blowout and reveal more detail.

Learn more about controlling exposure and adjusting it in post-processing from Jimmy Chin.