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A Practical Guide to Master Exposure Triangle in Digital Photography (Step by Step Illustrations)

A complete practical guide for photography beginners to learn and master exposure in digital photography

Exposure triangle is the most fundamental aspect of digital photography. Without understanding it, you cannot master exposure in digital photography. Use this guide to learn and master exposure triangle in photography.
Here is the story of a typical beginner in photography: 
You take pictures with your smartphone or with your previous automatic camera with just one click. You would get what you wanted. But you want to take your photography to the next level.
 So you bought a camera with manual controls so that you can do creative photography and level up your photography. 
 But now you can’t take even a normal photograph with your new camera because of all the manual controls. And using the automatic mode of your new camera would be pointless because it would be the same as your previous camera. 
 Understanding terms like shutter speed, aperture, ISO (even worse) are your new problems now, and it gives you a headache. Perhaps you already know shutter speed, ISO, aperture, and they are the components of exposure. But you just don’t know how to control the exposure with the three of them. And a trial and error approach would be impossible since there are three of them.
In this post, you will learn about the basics of exposure, the exposure triangle, how to adjust camera’s settings to master exposure of your digital photography. I have added an effective practice method for you to master the exposure. I used that method when I was a beginner and it helped me to understand and learn exposure in digital photography.
Let’s begin.

Basics of Exposure in Digital Photography — Exposure Triangle

 

To learn the basics of photography, you should know what is exposure, what affects exposure, and how you can manipulate exposure.

What is exposure?

Exposure is the amount of light a camera records. I know this information seems trivial, but knowing this makes a big difference. Because one of the common questions among beginners (including me when I was a beginner) was what exposure should I use. 
 
Let me explain
 
According to this definition, there is No right or wrong exposure. There is only the exposure you want. 
 
It means you have complete control over the exposure (if your camera offers semi or manual controls). Unless you use it, your camera cannot take pictures by itself. And you know that using a device with its full potential is about knowing the device first. So use of your camera’s manual to understand the settings of your camera. This guide will help you how to use your camera’s guide to learn exposure.
 
Now you know the definition of exposure.
 
Let’s look at it in-depth
 
Amount of light: we cannot measure the amount to light in liters or kilograms. Scientifically, it is measured as photons or quantum yield with respect to the device you are using. But let’s not talk about that, not useful here. 
 
Let’s look at it as the amount of light you want to record, as per your creative need. 

What affects exposure?

 
You might be wondering how you can control the amount of light the camera records. There are three ways you can control the amount of available light you can record (or control the exposure to take a photograph):
 
 
These are interdependent: When you change one of them, the other has to be changed to avoid change in exposure. In other words, when you change one of them the brightness changes, and you can change another component (or both) to undo the change in brightness.
As there are three components, you can connect them with a triangle. And we can call it the exposure triangle. And it looks like this: 
Exposure triangle in photography
Exposure triangle connecting Aperture, Shutter speed, and ISO
 
Exposure triangle? Huh?
I am not going to do any geometry lessons in this post. Don’t worry. I am going to explain exposure settings in this post. There is no particular rule in which where each of these goes in the triangle. The point is to show that they are related. 

Why the exposure triangle is important in photography?  

If you master the exposure triangle, you can predict the exposure settings for a photograph without even switching on the camera. That means you can take photographs in any situation quickly. You can master the exposure if you know how to use the exposure settings of your camera. 
Now you might be wondering why there are three components. If one can control the amount of light, that would be enough, right?
These three are the important components in an optical system that regulates the amount of light reaching the sensor. Each of these factors has limitations in the amount of light it can regulate. By integrating three of them, the amount of light can be expanded and manipulated in various ways. 

How does a DSLR camera work to create an exposure triangle?

The optical system of the three components (aperture, shutter speed, and ISO) are shown in the illustration. 
Illustration of how DSLR camera works
Illustration of how Light travels through a DSLR camera. Notice the various components that control the amount of light (exposure) you want to record.
 You can do some creative stuff with your photography by manipulating these factors because each of them is associated with a creative concept in photography. 
  • Aperture can affect the depth of field or the area of focus in an image.
  • Shutter speed helps you capture action or light trails (one of the most creative aspects of exposure)
  • ISO: nothing creative about it, unless you purposely want noise in your images. 

How to master exposure with the exposure triangle?

You know the basics now. Let’s master exposure.
When I was a beginner, it was difficult to master exposure although I knew the basics.
I developed a method to learn the exposure and take photographs without a doubt.
My learning process would look like this: 
photography exposure learning process
Basics help you to know why do you want to change the settings and what settings you should choose in a given situation. 
Some questions to easily learn the basics of exposure:
  • Why do you want to change the exposure settings?
For your creative need or to adjust the amount of light. Understanding the basics of exposure helps you to answer this. 
  • How to change the exposure settings?
Refer to your camera’s manual to change the exposure settings. Use this post to find out what settings are relevant to exposure. 
  • What settings should you choose in a given situation?
Practice the method in this post help you to understand exposure and decide what settings you have to change to control the exposure. 
Now, use your camera’s manual and find out how to change these settings in your camera. This helps you to take full control of the exposure settings. 
  • Should you choose manual-mode or semi-automatic mode?
You would see semi-automatic mode and manual mode when you read the manual.
Which one should you choose?
 Manual mode means you have to tell your camera what each of these settings is. Semi-automatic mode means you have to tell your camera at least one or two settings and the camera will select the remaining. Manual mode usually helps when the subject is dynamic or the light is dynamic and you want the exposure to be even in every shot. I usually use semi-automatic mode. It depends on your need. 
In this post, you will learn how to use manual mode to adjust the exposure and learn the exposure triangle.
Let’s practice this. 

Practical Guide to Learn Exposure Triangle (Step by Step)

 

Here is what you need to learn exposure in photography:

  • Camera with full manual controls
  • Your camera’s manual if you are an utter beginner
  • Tripod (optional)
  • A constant light source
  • A photo editor like  Photoshop or Affinity Photo 
If you don’t know how to use a DSLR camera manually or a camera with manual controls, you must use your camera’s manual. It would help you identify the buttons and settings that would help you to practice this tutorial. I can’t give instructions to use your camera settings here because there are so many different models of cameras out there, and it is impossible to guide you with just one model. But the basic settings mentioned in the post is the same irrespective of your camera’s model. 
Set up to learn exposure in digital photography with canon 7d mark 2
Set up your camera
  • Step #1: Use a tripod and mount your camera on it. I recommend this to avoid any change in the frame as it affects your exposure and makes everything inconsistent. If you don’t have a tripod, just keep your camera on a table or something. 
  • Step #2: Set a focal length of your lens. Don’t change the focal length throughout this practice.
  • Step #3. Focus on any object and illuminate it with a constant light source. If you use natural light, it may change and it would affect the exposure readings. Since you are learning this, I want you to use a constant light source. You don’t need to buy any external light source. Try this in indoor lighting.
  • Step #4: If you are using a DSLR, switch to your LCD view. I know you are supposed to use the viewfinder, but this would help you to see the exposure change in real-time. How cool is that! 
Only these information you need to learn this method
You can see the viewfinder display here. The information you need now is the aperture, ISO, and shutter speed and the light meter and histogram (some camera models do not display the histogram in LCD). Ignore the rest as of now. 

Methods of Changing Exposure

Now let’s change each of them, one by one. 
1. Change Aperture by keeping ISO and Shutter speed constant
I am using a 50mm lens because it can go from f1.8 to f22. You don’t need to use this. You can use any lens you have provided you can change its aperture. 


I am starting with aperture f2.0. You don’t need to start with this settings. You can use the widest (smallest f-number) aperture of your lens as a start. In each photo, take a note of the f-number and notice how the brightness of the image (LCD) changes. Relate the position of the pointer with the brightness. 
Exposure settings on LCD of DSLR
Exposure settings on the LCD of a DSLR. I used a Canon 7D mark 2. Aperture here is f2.0. The exposure settings are the same for all cameras regardless of the brand. Only the conventions of the exposure adjustments change with brands.

 

f2.2 aperture settings of dslr lcd
Changing the aperture to f2.2 changed the brightness to -1/3 stop.

 

f2.5 aperture settings on DSLR LCD
f2.5 aperture
f2.8 aperture settings on DSLR LCD
f2.8 aperture
I have changed the aperture one stop by changing the aperture from f2.0 to f2.8 (A stop is a standard unit of exposure. Increase the exposure to one stop means doubling the amount of light and decrease means halving the amount to light).
Here, each value is a stop. f2.1 is 1/3 stop less than f2.0. In other words, your lens can transmit only 1/3 less light than f2.0.
Notice the light meter reading in the LCD when you change the aperture. If it doesn’t move with a change in aperture, either you are using a semi-automatic mode or your light source is changing in manual mode. 
See how the brightness of the image changed. Noticed the histogram? It is more to the right now. Change the aperture settings back to the previous one to get a hang of this. 
The shutter speed and ISO did not change because you didn’t change it. This is why the brightness changed. You are controlling the light with just aperture now. You can make your image brighter or dimmer by changing aperture settings. 
Keep changing the aperture for all the values possible for your lens and notice how the brightness changes. And notice the histogram as well (if your LCD doesn’t display the histogram, you can take a photo with each setting and enable the histogram information when you view the image)
f3.2 aperture

 

f3.5 aperture
f3.5 aperture
f4.5 aperture of dslr
f4.5 aperture

 

f5.0 aperture
f5.0 aperture

 

f9.0aperture settings of dslr lcd
f5.6 aperture
f6.3aperture settings of dslr lcd
f6.3 aperture
f7.1aperture settings of dslr lcd
f7.1 aperture

 

f8.0aperture settings of dslr lcd
f8.0 aperture
f9.0aperture settings of dslr lcd
f9.0 aperture
f16 aperture settings of dslr LCD
f16 aperture. The image is 2 stops darker than the standard exposure
Now you know how to use aperture to change the exposure.
2. Change Shutter speed by keeping Aperture and ISO constant 
shutterspeed of 1/30 seconds
1/30 seconds, f1.8 aperture.
Did you notice the difference in standard exposure settings between the first photo of the aperture and this? In the aperture example, an f2.0 and 1/25 seconds shutter speed made a standard exposure (light meter reading in the center). Here f1.8 and 1/30 seconds made a standard exposure. This was because the light intensity changed (I was using natural light) while I took these photos. So you must use an artificial light source to avoid confusion.
I am going to slow down the shutter speed to increase the brightness of the image. Slowing down the shutter speed helps to let more light to the camera. Use the illustration to have an intuitive understanding of this. 
1/25 seconds shutterspeed
Shutterspeed 1/25 seconds.
1/20 s shutter speed exposure settings
1/20 s
Shutter speed 1/15 exposure for DSLR
Shutter speed 1/15 s
Exposure time of 1/13 s in DSLR
1/13 s

 

shutter speed settings on DSLR
1/10 s shutter speed

 

1/8 s shutter speed
Shutter speed 1/8 s

 

1/8 s shutter speed exposure
1/6s
Long exposure shutter speed settings
Shutter speed 0″4 seconds

That small triangle at the +3 meter reading shows that the settings are out of the dynamic range of your camera. If it is out of the dynamic range of your camera, then you would get blown out highlights on your photographs (those blinkies on the white region in your photographs). I have skipped few stops to save some space. 

Long exposure shutter speed on DSLR
1″3 seconds shutter speed
Alternatively, you can increase the shutter speed (faster shutter speed) and see how it decreases the brightness of the photograph. 
3. Change ISO by keeping Aperture and Shutter speed constant 
ISO settings of 7d mark 2
ISO setting of my 7d mark 2
Unlike shutter speed and aperture, the ISO settings of your DSLR would vary depending on the model of the camera. In entry-level camera, you can change ISO in integer stops ( 1/3 and 2/3 stops are unavailable for entry level cameras). You don’t need to full ISO settings to practice this. You can use what is available. When you change the ISO from 100 to 200, the sensitivity of the camera’s sensor doubles, which means it can capture double the amount of light. Understanding the value of ISO settings is intuitive.  The H1 and H2 modes in the photo is the hypersensitive ISO regions. It is like pushing the camera to capture more light in extremely low light situations. It is only available in semi-pro to pro-level DSLRs. 
You can follow the same method as you did with changing shutter speed and aperture. 
You must practice this every day to get the hang of using aperture, shutter speed, and ISO to manipulate exposure. 
But,  
We are not finished yet. You have only looked at each of the corners of the exposure triangle. You have seen that when you change one while keeping others constant, the brightness changed. 
But how do you change the settings without changing the brightness? In other words, how can you change your aperture, without changing the exposure?
Huh? Why do you want to do that?

Using Exposure Triangle for Creative Photography

Remember I told you that each of these has a creative aspect as well?
When you want to control that aspect (instead of the amount of light), you have to fix the amount of light reaching the camera. For that, you have to master the exposure triangle (or how to change other settings when you change one of them)
Let’s start with aperture
Aperture controls the depth of field. Too wordy, I know. It means, it controls how much blur the picture has (although this definition is not technically correct, this would help you in this context). It is used to make the background blur, as in portraits or in macro photographs (ah, now we are talking) 
But when you change the aperture, the amount of light changes, right?
Then how can you do both? — changing the depth while maintaining the same amount of light?
By changing the other settings
In what amount?
Let’s see that now
When you half-press the shutter button, notice the light meter blinking? That shows how much light is reaching the camera. It collects the information about the light. I will write about this in detail in another post. 
Scenario #1
Changing exposure setting in manual mode
Setting manual exposure with an f2.8 aperture value.
Using the standard exposure (light meter reading at the center), I have a shutter speed of 1/15 and ISO 100 for my choice of aperture f2.8. I don’t want to change the aperture because I need to blur the background. Slow shutter speed blurs photos. I have to choose a faster shutter speed.
changing exposure settings in manual mode DSLR
I choose a faster shutter speed of 1/30 s to avoid blur.
When I chose a faster shutter speed of 1/30 s, I halved the amount of light reaching the sensor of my camera. But I don’t want to change the amount of light. I want a standard exposure with this shutter speed (to avoid blur) and this aperture (to blur the background). What would you do to compensate for the loss of light?
Comment your answers 
Scenario #2
Can you tell me the difference between these two exposure settings?
manual mode of DSLR showing exposure triangle
F5.6, shutter speed 1/4 s, ISO 100 for a standard exposure
manual mode exposure change for exposure triangle
f5.6, Shutter speed 1/30 seconds, ISO 800
You can try this for yourself: Pick any combination of aperture, shutter speed, and ISO to keep the light meter reading in the center. And change each factors without changing the exposure. 

Your turn — What you can do with exposure triangle? 

Now you know how the exposure triangle works. In other words, you know how each setting are related and how to change them to get the right exposure (or the brightness you want). I suggest you transfer all the images in a photo editor that can display metadata (exposure settings) and histogram and compare the exposure of the images. 
But the technical aspect of photography is not just about learning the exposure although it is the basic aspect. Everything else about digital photography exposure is a derivative of the exposure triangle. 
Now the question comes:
What settings should you choose in a particular situation? I know you cannot spend time changing aperture, ISO, shutter speed separately. It would take time to take a photograph. 
For example, what aperture or shutter speed or ISO should you choose to capture a sunset, or a cloudy day, or a portrait.
There is no standard exposure setting for a particular situation. It depends on your creative need.  
I am sure you can master the exposure triangle with the method I gave here. I would suggest you practice this method until you become a master. This would not just help you to control the exposure in your DSLR, but you would know how your photograph would be in a particular lighting condition. 
With practice and experience, you would know the exposure settings when you see a lighting condition (sunset, daylight, indoor) without even switching on the camera. 
That’s it. Go and practice this simple method. 
And let me know how it goes. I want to know your answers to the two scenarios I described. 
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Vidhu Soman

Hi, I am Vidhu Soman, Editor of Shutterstoppers. I have been doing photography since 2010, and I co-founded shutterstoppers community in 2012. I love photography, writing, travelling, and reading. If you wish to contact me, send a mail using our contact form.

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