Exposure Triangle Explained and Made Easy!

Exposure Triangle Explained - Photography for Beginners

If you can understand the exposure triangle you have the basics of photography right down. You hold the keys to really understanding photography in your hands. So here goes - the exposure triangle explained in an easy way.

If you'd like to go a little deeper check our fun beginners online photography course: Photography Fundamentals. It goes into more detail on all the areas we looked at in this video and so much more! I can’t wait for you to join in on the action. We love teaching photography for beginners and this course is fun, it’s quirky, it’s one heck of an online photography course!

If you scroll down there's a video to accompany this article, but you'll learn far more if you both read and watch (plus we tend to put more little golden nuggets in our text articles). Scientific studies have been done on this - really! It's called multi modal learning.

If you have any questions, don't forget to ask in the comments section below!

Exposure - Basics of Photography

To understand the exposure triangle and all that ensues we need to look at what we mean by "exposure". 

Exposure here is really talking about the the brightness of the image.

Staithes, Under-Exposed


Staithes, Correctly Exposed


Staithes, Over-Exposed


You can see how the exposure affects the image  in the graphic above.

If an image is "under exposed" it will look too dark, and the detail in the blacks and shadows will be lost. To correct this exposure we either need to increase the amount of light hitting the sensor, or increase the perceived sensitivity of the sensor to available light.

If an image is over exposed - it will be too light and the detail in the whites and highlights will be lost. To correct this exposure we either need to decrease the amount of light hitting the sensor, or decrease the perceived sensitivity of the sensor to the amount of available light.

For now think of exposure in terms of image brightness, like the graphic above showing under and over exposures. Let's learn the concept first in the easiest way possible.

The Exposure Triangle - the basics

Exposure Triangle explained

This graphic is the exposure triangle. Each side of the exposure triangle represents a setting on your camera which you can change up and down. Let's take a look at each side / setting to understand it's relevance to exposure:

Think of ISO as the setting which tells your cameras sensor to be either more sensitive, or less sensitive to light. Technically it's a bit more complicated - see below.

Aperture is a hole in the lens through which the light travels on its way to the sensor. You can adjust the size of this hole to let more or less light though.

Shutter speed is the amount of time the shutter is open while the image is being taken. A slow shutter speed lets more light in and a fast shutter speed lets in less light.

It's understanding the exposure triangle and the inter-relation of these three key elements that is fundamental to understanding the basics of photography.

Ready to move to the next level?

Online Beginners Course!

Only £97!

The Exposure Triangle - getting the correct exposure

As we've just learned the three elements of the exposure triangle - ISO, Aperture, and shutter speed, make the correct exposure.

Getting a correct exposure is fundamental to photography basics. 

Let's give the correct exposure a numerical value of, say, 10. Now if we give the ISO, aperture, and shutter speeds numerical values, and they collectively add up to 10 then we have a correct exposure.

3 + 3 + 4 = 10

That's the basics of photography. Sort of. The thing is, we don't just want to get a mathematically correct exposure. We want to get a creative exposure. And that is the difference between allowing your camera to do things on auto, and you jumping right in there and setting the exposure yourself.

The Exposure Triangle - getting a Creative Exposure

The key to understanding the basics of photography well is this. It doesn't matter what numerical value you give to any one element of the exposure triangle as long as the collectively add up to a correct exposure.

3 + 3 + 4 = 10

7 + 2 + 1 = 10

2 + 6 + 2 = 10


Now you may say, my exposure triangle adds up to a perfect 10 whey would I worry about how they add up?

And drumroll please...

Your shutter speed and your aperture settings can make a huge difference to the creative effect of a photograph. Huge. Let's look at each element of the exposure triangle to see why they are each, individually, extremely important.


Your aperture setting controls how much in front of and behind your image is in focus. This is referred to as "depth of field" - a shallow depth of field will give you blur in front of and behind your subject, where a wide depth of field will ensure far more is in sharp focus. 

If you've ever admired those portraits with blurred backgrounds - that effect is about aperture. Knowing what effects aperture produces is fundamental to understanding photography basics.

Aperture is the difference between these two photographic effects:

Small Aperture 

This image uses a small aperture to create a large "depth of field". Aperture is measured in f numbers. A large aperture is a small f number e.g. f/4. A small aperture is a large number e.g. f/22. If this isn't making sense, think about fractions.

Small aperture photography basics

Large Aperture 

This image uses a large aperture to create a shallow "depth of field", throwing the background out of focus. 

large aperture basics of photography

Hopefully it will now be apparent why you might want to set this part of the exposure triangle - the aperture, and manipulate the others to compensate for a correct exposure. The images above wouldn't have worked without being shot at a set aperture.

If you'd like to know more about aperture click here for my aperture basics video. 

Shutter Speed

Shutter speed is responsible for two effects. It can be used to freeze fast moving action (fast shutter speed), or it can be used to create motion blur (slow shutter speed)

Slow Shutter Speed 

A slow shutter speed (1/2 second) was used to create the motion blur and circular light streams on this carrousel. 

Slow Shutter speed photography basics

Fast Shutter Speed

A fast shutter speed  (1/1600 seconds) was used to freeze Bailey the Spaniel in mid air.

fast shutter speed exposure triangle explained

Hopefully it will now be apparent why you might want to set this part of the exposure triangle - the shutter speed, and manipulate the others to compensate for a correct exposure. The images above wouldn't have worked without being shot at a set shutter speed.

If you'd like to know more about shutter speed and precisely how we got this image of Bailey check out my video on YouTube here.


Think of ISO is a control on your camera that controls how sensitive to light your sensor will be. Technically it does this by amplifying the signal from your sensor rather than the sensor itself being more sensitive, so we're really talking about perceived sensitivity rather than actual sensitivity.

Say for example there is very little ambient light and you want to freeze action with a fast shutter speed. Here your aperture alone is unlikely to be able to let in enough light to create a correct exposure. You will therefore want to turn your ISO setting up making it, in effect, more sensitive to light so that the camera can "expose correctly".

Noise ISO exposure triangle photography

Much "digital noise" is visible on this picture when zoomed in like this. This can easily happen if you are shooting on a high ISO.

One issue with ISO is that at high ISO, where the camera has a perceived high sensitivity to light you will get digital noise appearing on your image which looks like this image.

As a rule of thumb you'll start seeing a lot of digital noise at ISO numbers such as 1600, although it very much depends on the quality of your sensor.

Low ISO numbers such as ISO 100 show very little digital noise.

ISO isn't a part of the exposure triangle responsible for creative effects, but without if it the elements that are - shutter speed and aperture - would find it hard to work their magic.

Technical note

Historically exposure referred to the amount of light to which the glass plate was "exposed" while the photograph was being taken. It was "exposing" the glass plate to light that created the image.

Today exposure can means either:

1 - The amount of light that reaches the camera's sensor i.e. the amount of light the sensor is "exposed" to when the image is taken. This is is sometimes called "luminous exposure" as a technical concept with a horribly mathsy equation.


One of two colloquial terms:

2 - The brightness of the final image - This is the type of "exposure" the exposure triangle refers to


3 - The final product - the image file taking into account all it's components and component settings

Arguing whether one of these definitions is technically right or not isn't really the point because all these meanings are ingrained in photography language. When we talk of exposure we could mean any single one of them! Bonkers right?!

All 3 concepts of exposure evolved out of the historic act of "exposing" a plate to the light creating an image. Arguably when the concept of exposure was first coined all 3 definitions meant the same thing. The exposure to the light was a direct cause of the image brightness, and a direct cause of the final product. 

Then the massive evolution of technology and language happened and they all mean something different. It's a bit like using the term "dialing a number" today using your mobile or cell 'phone.

Your camera will help you out

How to set your camera to use what you've just learned is a whole other lesson and also depends to some extent on your particular camera model. 

For now all I'd say is your camera will always help you out. Even in fully manual mode your camera is constantly monitoring whether you're over or under exposed so that you can make adjustments to your exposure triangle settings to get that perfect 10.

(And if you read that technical note - when monitoring whether over or under exposed does take into account ISO).


I hope you can now see how the Exposure Triangle works, and that it is an integral part of learning the basics of photography. You now have the keys to nailing so many different photographic effects.

Here's the video we teased...

Here's the video we teased you with, all the way from our YouTube channel.

And, yes, this video may "fudge" terms so as not to confuse the real issues, and understanding of the actual concepts at play.

Would you like to really master the photography basics?

We've just given you the photography basics in a nutshell, but would you really like to master them, and so much more?

If so we really think you’ll enjoy our online photography course: Photography FUNdamentals, there is something for everyone and you will be able to learn so much about photography. 

We have a whole module dedicated to camera craft which includes chunks on shutter speed, aperture, ISO, and the cool effects they can give you. We'll show you how to master your camera's modes so that for every scenario you'll know the best mode to pick and how to key the right exposure triangle settings. We also cover composition and kit.

It’s an online photography course with a difference. We try and make photography for beginners fun and easy to understand. You’ll find easy to follow graphics, cheat sheets, exercises an online learning community and so much more.

If you would like more information and help with photography for beginners, please click here to buy the course now.

Banner Photography Fundamentals AB 16x9
{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}

Get in touch

Please get in touch if you have any questions, if there is anything you'd like us to cover, or if there's anything else you'd like to say. We'd love to hear from you!