If there’s anything that most beginner photographers looking to hone their craft get confused about, it’s the exposure triangle. In fact, the exposure triangle, or the combination of aperture, shutter speed, and ISO, is one of the most complicated concepts photographers have to master before they can consider themselves an expert.

The exposure triangle is amazing when all three variables work together seamlessly to produce flawless photos. But the problem is if even just one of the three exposure variables is off, it won’t matter how beautiful your subject is, your photo will be either incorrectly exposed or simply out of focus.

In today’s post, we’re going to take a closer look at the exposure triangle in simple terms so that you can have a better understanding of this crucial photography concept.


What is the Exposure Triangle?

In photography, exposure is the amount of light that is captured when a photo is taken.

After that, you have the exposure triangle, which is made up of three parts:

  1. Aperture
  2. Shutter speed
  3. ISO.

They work together to produce a photo that is properly exposed. When one variable changes, at least one of the other variables must change too in order to maintain the correct exposure by compensating.

If the exposure of a photo is off, you’ll notice the image is either too dark or overexposed – in other words, far too bright.

Before diving into the exposure triangle, it’s important to understand what the term stop of light refers to:

Stop of Light: a stop of light in photography refers to the halving or doubling of the amount of light that makes up an exposure. Each photo you take requires a certain quality and amount of light to be exposed correctly. Adding a stop of light by doubling the exposure will brighten an underexposed image. On the other hand, decreasing the exposure by one stop of light (and thus halving the exposure) will darken an overexposed image.

So, how do you add or take away a stop of light while taking photos? The answer is change the exposure triangle variables. In other words, adjust the aperture, shutter speed, and/or ISO.

Now let’s take a look at each part of the exposure triangle to see how they all work together to produce perfectly exposed photographs.


Variable 1: Aperture

aperture

Aperture is the measure of how far open or closed the lens iris (the circular hole in the lens) on your camera is.

  • Wide Aperture: the bigger the hole, the more light that comes in.
  • Narrow Aperture: the smaller the hole, the less light that comes in.

If you double the area of your lens opening, you double the amount of light that comes into your camera. This is also equal to increasing the exposure by one stop of light.

If you halve the area of your lens opening, you halve the amount of light that comes into your camera. This is also equal to decreasing the exposure by one stop of light.

Why control aperture on your camera?

The reason you would want to control the amount of light that comes into your camera and hits the sensor inside is because doing this helps control the depth of field. The depth of field is the distance between the nearest and furthest objects and the acceptable amount of sharpness within a photo that is in focus.

Let’s look at some examples to make this clearer.

Wide apertures create a narrow depth of field, which isolates a subject that is close and causes the rest of the photo to be out of focus. A great example of this is in portraits, where the person is clear as can be and the background is blurred out of focus.

wide-aperture-example
A wide aperture puts your closest subject into focus and blurs the rest.

Narrow apertures create a greater depth of field, which allows more of the photo to be in focus. A great example of this in in landscape photography, where more the entirety of the image is in focus and every detail can be seen.

narrow-aperture-example
A narrow aperture allows the objects in your image that are farther away to remain in focus.

Variable 2: Shutter Speed

Shutter speed is the measure of how long (in seconds) the shutter on your camera remains open and how long the sensor inside your camera is exposed to light.

Faster shutter speeds give the sensor less time to collect light and results in a lower exposure. They can stop motion, such as a camera shake or subject that is physically moving, without sacrificing details.

faster-shutter-speed-short-exposure-example
Fast shutter speeds can capture movement and maintain the details.

On the other hand, slower shutter speeds allow more time for the sensor to collect light and results in higher exposure. They can record images as the shots are snapped for a longer period of time resulting in a fluid, or sometimes blurry, effect.

In fact, if you have the right exposure triangle settings, slow shutter speed has the potential to give your moving subject matter a unique look and feel.

slower-shutter-speed-long-exposure-example
A slow shutter speed still captures movement but blurs it in a unique way.

Why control shutter speed on your camera?

The reason you would want to control the amount of light that hits the sensor on your camera is to ensure the subject matter of your photo stays sharp and the details are not lost. Of course, unless that’s your goal. Then, by all means, slow those shutter speeds down.


Variable 3: ISO

iso-on-a-camera

The last variable of the exposure triangle is ISO. This is the most complicated of the three variables. That’s why for beginner photographers it’s easiest to think of ISO as the sensitivity of the digital sensor in your camera.

  • High ISO values mean the sensor needs to collect less light to make a correct exposure
  • Low ISO values mean the sensor needs to collect more light to make a correct exposure

Adding to that, it’s good to know that doubling the ISO means an increase by one stop of light. Conversely, halving the ISO means a decrease by one stop of light.

Why control the ISO on your camera?

Increasing the ISO allows you to work with less light and still shoot amazing photos. After all, there comes a point when the aperture is as wide as possible and the shutter speed is as slow as possible to stop the action and capture a still shot, without any blurring.

That means the only thing left to do is adjust the ISO. However, the trade-off is more noise and less detail when you increase the ISO.

Noise in photography happens because there are random fluctuations in the electrical signal while you’re taking pictures. In less technical terms, noise is when the pixels in your photo turn funky and your images look grainy.

noisy-image-example
(Image Source)

Because of this trade-off, it’s important you evaluate a shot before adjusting the exposure triangle. If you’re okay with a little noise, so long as the subject matter remains relatively clear, keep the ISO high. If you want to eliminate the noise, and are okay with a softer, less detailed subject matter, then lower the ISO.


The Exposure Triangle: Conclusion

Understanding the exposure triangle is an important part of becoming a better photographer. If anything, knowing how aperture, shutter speeds, and ISO work together will help you learn how to use your camera more effectively.

So, if you’re ready to take your photography skills to the next level, make sure to include learning about the exposure triangle so you get the best photos possible every time you shoot your camera.

And while you’re at it, make sure to check out the best places on the internet to learn photography. And don’t forget, once you’re ready to start making money off your newfound photography skills, be sure to check out our guide to becoming a successful freelance photographer to help you out.

What are your best tips for balancing the exposure triangle while taking photographs? We’d love to hear all about it in the comments below, or Tweet @WPModula and tell us all about it!