One of the most important components of a good photo is light. Too much light, or not enough, can ruin what would otherwise be an amazing photograph.
Learning how to control how much light is in your photo is an essential part of learning how to take good photos. The exposure triangle is the combination of aperture, shutter speed, and ISO of your camera that helps you control the light in your photos.
How does the exposure triangle work?
The three components of the triangle work together to create a photograph. When you change one component it affects the others. If you increase the ISO, you will also have to change the f/stop and the shutter speed to compensate to keep your photograph exposed correctly.
- Aperture is the opening in a camera lens that allows light to pass through. Adjusting the aperture changes the amount of light that hits your sensor, as well as the angle at which the light passes through the lens. The ratio of the opening versus the size of the lens is referred to as f/stop or f/number.
A wider aperture (lower f/stop) lets more light into the camera and gives you a shorter depth of field to focus on your subject, like in the example below. A smaller aperture (higher f/stop) lets less light in, but gives you greater depth of field. F/stops are on an exponential scale, not linear, so if you change your aperture from f/8 to f/4, you’ve quadrupled the amount of light passing through the lens.
- ISO is a measure of how sensitive your camera’s sensor is to light. A higher ISO means more light being received by your sensor. For example, if you start shooting at ISO 400 and then change to 800, you’re doubling the sensor’s sensitivity to light. Shooting in low light requires a higher ISO, but it can cause more “noise” or graininess in your photos.
In the example below, you can see how a photo taken with a higher ISO captures some details in darker areas, but also results in washed-out colors and a less contrasting image overall. Finding a balance is key.
- Shutter speed is a measurement of how long your camera shutter is open, or in the case of some digital cameras, how long the sensor is on. The longer the shutter is open, the more light that comes through your lens, and the more movement is captured in your photos.
A slow shutter speed is often used to convey motion in a photograph, like moving water, waves, or stars. It’s also an easy way to take photos in low light. Be sure you have a tripod on hand, though. Shaky hands have ruined many a photographer’s slow shutter speed photos.
Faster shutter speeds are excellent for capturing a moment in action, like a sports event, animals, or birds in flight. This reduces the amount of light hitting your sensor, though, so make sure your ISO and aperture are adjusted accordingly.
In the photo below, you can see how a fast shutter speed captures every drop of water, while the slow shutter speed results in a softer spray and shows the motion of the hand.
How do you master the exposure triangle?
In order to master the exposure triangle, you need to practice! Pick a subject and photograph it over and over, changing settings as you go.
Since you now have a basic understanding of what each component does, try to aim for certain effects. Shoot some running water and play around with shutter speed, or do some nighttime photography. The more you practice the more you’ll understand how different adjustments affect your photos.
