Exposure triangle in photography – what is it and how does it work?

Why learn about the exposure triangle?

The exposure triangle is the most important photography concept to learn. If you can understand the exposure triangle, you can get out of auto mode and into manual mode, which is the ultimate goal.

This is how you take control of your camera and exposure in photography to get the results you intended.

In this tutorial we’ll:

  • Take a look at why knowing how exposure triangle works is essential for photographing in manual mode
  • Think through exposure triangle settings for a particular scenario
  • Walk though the exposure options for a shoot and examine the results

Exposure triangle for beginner photographers

How does the exposure triangle help with manual mode?

Before you take the shot, you must first:

  • decide what you want the photograph to look like
  • think about your subject, or subjects
  • then you look at the location and the light

Based on this you then:

  • decide where you’re going to position your subject, or yourself
  • then set your aperture, shutter speed and ISO accordingly and create your image

Sounds easy, doesn’t it?

Well, with practice it is, but to start with there’s a lot of stuff going on inside your head. It can be tough to remember how everything works and set your camera correctly.

And then! You actually have to take the shot before either the light changes or your subject disappears or gets bored. It’s a lot of stuff.

If you can cook a meal for a group of people, you can do this. You weren’t born knowing how to cook or drive or walk. You learned, practiced, got better and now you don’t even think about it.

Like everything, photography is a process.

Deciding exposure in photography is like preparing a meal

Let’s take the simplest cooking task – heating up a frozen pizza. Even for this simple cooking task, you have to make a series of decisions to get to a particular end result – a well cooked pizza. You have to think about:

  • How many people are there?
  • When do we need to eat?
  • How long is it going to take to heat the pizza?
  • What temperature must I set the oven at?
  • How long will it need to be in the oven?
  • What am I going to put the pizza on to cook it?
  • How am I going to serve it?

What does cooking have to do with exposure in photography?

Okay, so relating that to photography, let’s think about the steps that we need to take to create a photograph. As an example, let’s take a photograph indoors of an apple on a table in front of a window.

PS: This scenario would fool your camera if you shot it on auto. With all that backlight coming in the window behind the apple, the camera will underexpose the shot. So, you also need to know the correct exposure metering mode for the situation.

Further reading on metering: Understanding how exposure metering works

Exposure factors to consider…

Excluding composition and what metering mode to use, here are some of the questions that are going to come to mind when setting exposure in photography:

  • How bright is it today? Is it a really sunny day or is it overcast?
  • Where is the sun? Is it shining directly into the window or not?
  • Do I want strong direct light on my apple or do I want diffused light on my apple?
  • Do I want the background to be completely blown out or do I want some detail in the background?
  • How far away is the background?
  • What feel do I want to create?

That’s a lot of questions for one simple apple photograph! They’re all relevant as part of the process of deciding what you want to create.

Photography is made up of rules and many times those rules are bent or just plain broken in the name of creativity, which is great. However, there’s no getting around the exposure triangle.

How to use the exposure triangle to photograph in manual mode

Here’s how I like to think of it:

The exposure triangle is a gang of inseparable friends: aperture, shutter speed and ISO. They always hang out together, always take turns to be in the lead and they always, always adjust according to who is in the lead.

Thinking through Exposure Triangle settings for our apple shoot:

Bearing in mind the inseparable friends… We’re going to shoot the apple two ways:

So we need to consider aperture, ISO and shutter speed for the correct exposure and to change the mood of the photo.

What’s aperture got to do with exposure in photography?

Aperture controls the width of the hole in your lens that lets light in. The wider the hole, the more light enters, and the shallower the depth of field (blurry background).

In both scenarios we’ll decide on our aperture first. Why?

Because aperture is all about the details of the image.

  • For the light and airy scenario we want our apple to be isolated against a blurry background
  • In the moody scenario we want detail in both the foreground and the background

Besides, apples don’t run around, so we don’t have to take shutter speed into consideration.

Further reading: 

What does aperture do in the exposure triangle?

4 ways to use isolation in photography composition

What are stops in photography exposure?

Shallow depth of field from wide aperture in exposure triangle

What’s ISO got to do with exposure in photography?

ISO controls your camera’s sensitivity to light. The higher the ISO, the more sensitive it is to light.

Because ISO impacts on the noise (what used to be called grain in the days of film) in an image, and the apple is still, ISO is our next important decision.

We don’t want lots of noise in the first shot, because we want light and airy. Also, it’s a sunny day, so shooting on a low ISO is easily achievable.

In our second shot we’re going with moody, so we’re introducing noise in camera by shooting with a high ISO.

Further reading: 

What is ISO for in the exposure triangle?

Auto ISO – pros, cons and how to use it

Increase ISO in low light for exposure in photography

What’s shutter speed got to do with exposure in photography?

Shutter speed controls how long the shutter is open and therefore whether movement is frozen or not.

Shutter speed is not a priority at all in this instance, as the apple is not moving and the camera is mounted on a tripod. So we set our shutter speed to accommodate our first two priorities, aperture then ISO, while bearing in mind how bright we want the scene to be.

Shutter speed is therefore used purely to control the brightness of the image on this occasion.

Further reading: Shutter speed and the exposure triangle – what does shutter speed do?

Let’s do this shoot already…

So, we’re going to shoot our apple:

  • On a sunny day
  • On a table directly in front of the window
  • With no direct sunlight shining on it

First we’ll create a light and airy feel and then we’ll create a photograph of exactly the same scene, but with a moody feel.

Light and airy apple shoot

We’re going with a light and airy feel first. In other words, not a lot of contrast, so no strong shadows.

  • We want lots of light, so we’re going to blow out the background.
  • We’re going to position a reflector in front of the apple to bounce light back onto the apple and reduce the shadow on the side facing us.
  • We want a really blurry background and foreground, so we’re going to shoot at F2.8. All the attention is on the apple as it’s the only sharp element in the photograph.

Further reading:

How to use a reflector properly and why you really need one

Using depth of field for gorgeous photography composition

Our exposure triangle combination is:

  • A wide aperture (small F number)
  • And a low ISO
  • So we need a medium shutter speed

Exposure triangle settings: F2.8, ISO 100, 1/125

Using the exposure triangle to overexpose background and use fill light

  • Because the aperture is wide (small F number), a lot of light floods into the lens.
  • The ISO is set low, so the sensor is not very sensitive to all the light flooding in and therefore doesn’t create any noise.
  • As a result, our shutter speed setting is slow to medium so that the light hits the sensor for longer to over expose the background and blow it out.

Moody apple shoot

Now we’ll try bit of mood. We’re going to shoot the exact same set up, but with lots of contrast between light and dark.

  • We’re going to have moody dark shadows and we’ll create noise with a high ISO for some grittiness.
  • There’s no need for a reflector, as we want a good amount of shadow on the apple.
  • We’ll expose for the background to make sure that the apple is dark and silhouetted, to emphasise its round shape.
  • Let’s shoot at F16 so that we have front to back sharpness on the apple, detail in the table beneath the apple and some detail in the background.

In the moody scenario our exposure triangle combination is:

  • A narrow aperture (big F number),
  • A high ISO
  • And a fast shutter speed.

Exposure triangle settings: F22, ISO 8000, 1/2000
underexposed image with noise

Even though the aperture is smaller, therefore less light gets in, we’ve really cranked up our ISO to achieve noise, so the sensor is very sensitive to all the light flooding in.

We have to reduce the amount of time the light hits the sensor, or the background will be overexposed, which we don’t want this time.

Therefore our shutter speed will have to be fast to achieve the correct exposure.

But what if we change just one thing?

As you can see, adjusting the exposure triangle settings can make exactly the same scene look and feel completely different. So, let’s drill down a little bit more by shooting the same scene, but changing only one of the exposure triangle elements.

For this image the ISO is set to 100 and the aperture to F2.8. Here’s what happens when you change just the shutter speed:
exposure change with decreased shutter speed

Now we’re going to change just the aperture. For this series of images the ISO is set to 8000 and the shutter speed to 1/8000.

changing the aperture changes the exposure

As can be expected, the exposure changes with each shot, from underexposed to overexposed. The correct exposure for the scene is the one that fits the mood you wanted to create.

The next two contrasting images have the same exposure value. In other words, they are equally as bright. There’s a huge difference though in the depth of field. One has a blurry background, the other has front to back detail.

So here we created two images that are equally bright, but with completely different settings to get completely different looks.

And that is the magic of using the exposure triangle creatively!

control exposure triangle to create mood

Contrasting images of the same scene create two different moods:  peaceful and then gritty.


Your exact exposure triangle settings depend on:

  • Where you are
  • Time of day
  • How sunny it is (or how bright your flash is set)

This is an important point, because I’ve noticed a lot in Facebook groups that people ask what settings they should use in xyz scenario…

Just because somebody shot xyz at f2.8, ISO 100 with a shutter speed of 1/125 doesn’t mean that the same will be true for you shooting the same subject. Well, not unless you’re standing right next to them, shooting the same subject at the same time.

That said, there are of course guidelines for achieving certain results. But they’re just guidelines.

For example an aperture of f2.8 is going to achieve more background blur than an aperture of f8.

Another example is if you’re photographing young, busy children, your shutter speed should be at least 1/250 to freeze movement.

Use fast shutter speed to freeze water

Camera settings: F4 at 1/640

Do you see why you need to understand the exposure triangle?

The point is that, once you understand how the exposure triangle works, you’ll be able to achieve your desired result by deciding on what’s important to you in a certain scenario.

This is why photography is so creative. Photography is not about pointing your camera at something and letting it decide on the best settings to capture that scene, which is what auto mode does.

The only creativity you have in auto mode is deciding on your composition.

In auto mode your camera will use matrix metering (Nikon) or evaluative metering (Canon) to expose the scene, which is not always the correct metering mode to use. If you have’t used the correct exposure metering mode for the situation, your camera won’t expose it correctly.

Also, some situations will always fool the camera, like snow or a sandy beach. So you need to know when it’s going to get confused and then how to handle it. We go into exposure metering modes in detail in another blog.

Further reading:

How to control exposure – reading the exposure indicator

Understanding how exposure metering works – controlling exposure part 2

Photographs tell stories

Humans are hardwired to love stories. It’s how we communicate and there’s a reason we say a photograph is worth a thousand words. A photograph is a story summed up into one brief instant to be told over and over again.

To tell a story photographically, you need to set out with a particular look in mind. If you know how the exposure triangle works, you can control the look of the image and infuse emotion into your story.

You need emotion, because all good stories evoke emotions.

Emotion is what sets an amazing image apart from an accurately exposed image. If you can inject mood and personality into a photograph you’ll make people stop and look at it, because you’ve appealed to their emotions.

Chasing the perfect image to tell exactly the story you want to tell is where photography becomes THE most satisfying obsession. When the planets align and you get that shot the way you imagined it, the sense of achievement is phenomenal. It’s the reward for all the frustration of getting to that point.

Start telling your stories creatively

All you have to do is understand how aperture, shutter speed and ISO work together as members of the exposure triangle gang.

Further reading:

What does aperture do in the exposure triangle?

What’s shutter speed for in the exposure triangle?

What is ISO for in the exposure triangle?

Then learn about focusmetering, white balancecomposition and creative techniques.

Further reading:

The ultimate sharp focus guide for photos you can be proud of

Understanding how exposure metering works – controlling exposure part 2

What is white balance in photography and does it matter?

19 photography composition tips you need to know to be awesome

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