Whether you are a beginner or a professional, one of the most important elements of photography involves something called the 'exposure triangle' - which is the relationship between shutter speed, aperture and ISO.

Beginner

An understanding of the 'exposure triangle' can dramatically improve your photos, and this beginner's guide will help you understand the basics of what it is and how it impacts every photo.


What is the exposure triangle?

Think of the exposure triangle as the blueprint of every photo taken. Whether that is with a smartphone or a DSLR camera, 3 elements combine to allow you to take a photo.

These are:

- Shutter speed - it determines how fast the shutter on your lens opens and closes.

Aperture - measured in f/stops, this setting determines how open or close your aperture will be and in turn how much of your scene from the foreground to the background will be in focus.

- ISO - this is the sensitivity of the sensor to light. The higher it is set, the more sensitive your sensor will be. So, you will be able to take photos in darker conditions. Read our guide to ISO here.


The reason this is called a “triangle” is that the three settings are connected. Which means changing one will impact the other two and allow you to be able to take a photo at the correct exposure level.

For example, selecting a smaller aperture – in other words a higher f/number or greater depth of field – means the shutter speed will be slower. But if shooting without a tripod this can result in blurred photos, so an alternative is to select a higher ISO, which allows for a faster shutter speed.

The “triangle” is simply an explanation of the connection between these settings.


Why is the exposure triangle so important?

As mentioned above, every photo that you take will require you to set the three settings above. Even in automatic mode the same principle applies, the only difference is that the camera does this for you.

Understanding the exposure triangle will help you in two situations - it will help you get the best settings for your shot out of necessity and out of creativity (i.e. because you want a particular look for a photo).

Exposure settings displayed on the LCD display of a Canon DSLR.

Necessity


Sometimes photography is about compromises. You have to select one setting to allow you to be able to select another one so that you can capture the photo that you want to take. This is often to do with shutter speed.

Your shutter speed determines how quickly the shutter on your lens opens and closes. We humans can only hold a camera steady enough at fast shutter speeds to avoid camera shake. At slower speeds you will end up with a blurred photo.

For most, this will mean a minimum shutter speed of 1/60th sec. Some people might be able to go slower for handheld shots while others might need to have a faster shutter speed. The only way for you to know is to test yourself and look at the results on your computer screen to see how slow you can go. But no-one will be able to hold a camera steady enough for even 1 second to avoid a blurred shot. So sometimes you have no choice but to make adjustments to allow you to be able to shoot handheld.

For example, if you are taking a photo in low light conditions such as a covered market you may struggle to select a fast-enough shutter speed to be able to shoot handheld. This is where understanding the exposure triangle and the relationship between the settings can help.

To be able to have a faster shutter speed you need more light to be hitting the sensor. Based on the triangle above, you have two options. You can either increase your ISO (keep in mind that a higher ISO will mean more noise in your image), or you can select a wider aperture with a shallower depth of field like f/2.8. This will allow more light to enter the camera and allow you to take the photo at a fast-enough shutter speed to avoid using a tripod.

This shot was taken on a cloudy day and in a narrow alleyway and the artist was moving a fair bit.To make sure that the subject was sharp I set the following settings: 1/200s @f/5.0, ISO 400.

Creativity


Sometimes it won’t be necessity that determines your settings but the way you want a photo to look. For example, imagine you are photographing a landscape scene and want to capture movement in the clouds. This means you will need a slow shutter speed to be able to capture the motion of the clouds. But as this is a landscape shot you also need to have a greater depth of field so that the foreground to your background is in focus.

As mentioned earlier, these settings are connected and changing one impacts another. In this scenario, selecting a higher f/number such as f/16 (for greater depth of field) will reduce the aperture which means less light. Less light coming in also means a slower shutter speed. Without a slower shutter speed, the photo will look too dark, and be "underexposed", which means the scene wasn't given enough light and will appear murky.

So, by selecting your aperture you have also influenced your shutter speed at the same time to what you were looking for to be able to capture the motion of the clouds.

To make sure the water was smooth on this calm day and for a long depth of field, my settings were 6 sec @ f/16, ISO 100 (using a tripod).

How to master it?


The good news is that with practice you will naturally become better at realising the impact that one has on another. Eventually it will become subconscious to you and you will be able to make decisions while you are taking photos based on the photography challenge that you will face. So, you will be able to decide what to compromise on to allow you to select the settings that you need.

The best way to improve your understanding of this concept is to also try to learn more about each of the elements of the exposure triangle. By learning more about depth of field, shutter speed and ISO you will be able to understand their relationships with another better.


Remember just one thing…


Hopefully, you now have a better understanding of the exposure triangle.

But just to recap, the exposure triangle is the relationship and impact that depth of field, shutter speed and ISO have on every photo and each other.

So, grab your camera and experiment with every different aspect of the exposure triangle to see how they impact each other. And most importantly... have fun!