A Beginner Photographer’s Guide to The Exposure Triangle
Learn about the exposure triangle, what it is, how to use it and how to make it work for you!
When I first started out in photography, I was using my iPhone. I pointed it at what I wanted to capture, the phone handled everything for me and I had decent photos. I started to enjoy it more and more and so I went out and purchased my first camera, a Canon 80D with a kit lens (18-55 f/3.5-5.6) and headed out into the city at night. I got home and thought the camera was busted. Nothing was in focus, I had what I now know to be motion blur all over the images and I was really disheartened because I thought I had wasted a ton of money.
This is a long one, so grab a coffee and settle in….
I needed to address these issues, find out what was causing them and then practice.
I watched some YouTube videos and read about what I needed to do to make some progress. I’ll let you into a little secret ahead of time… practice. Practice is your friend, it’s where you make mistakes and it’s where you then find out how to correct those mistakes. Coming from a music background, I really appreciated the value of practice, and it’s still something I do now. If you’re not prepared to make the mistakes and learn from them, then you need to shift your mindset! (I know I have said practice a lot, but I hope that it’s helped to get my point across!
What I found out was that exposure triangle was something that I needed to know. And know inside out. This, alongside knowing my camera and what it was capable of were key to me being able to develop (no pun intended) my skills. Once I could do this, I then started to focus on other things, mainly composition, because we all know composition is king but well composed photos that were either under exposed, over exposed or were blurry because of camera movement or camera shake were of no use to me.
So what is the exposure triangle? It’s made up of three things:
Left: The Exposure Triangle.
ISO: How sensitive your camera’s sensor is to light.
Shutter Speed: How long the shutter is open to let light into the camera and hit the sensor.
Aperture: How wide the aperture of your lens is open to allow light in to the camera to strike the sensor.
Each of the these parts of the exposure triangle has an impact on the image that you want to take. There are also “trade-offs” that you might have to consider, because if you adjust one, you might (almost certainly will) have to adjust another to compensate. Here’s a quick breakdown.
ISO: Can introduce digital noise into your image and this, at times, can look unsightly. Different cameras handle high ISO better than others, but essentially, the higher the ISO, the higher the risk of noise. Knowing your camera really helps here, I know that I can push my 80d to around ISO 6400 before it starts to negatively impact my images. Sometimes you will want noise, but that’s an artistic choice and you need to know how far you can push your camera and your raw files.
Shutter Speed: Again, knowing your camera (and your lens) really helps here. A lot of newer cameras have solid IBIS (in body image stabilsation) which can help to minimise camera shake and unwanted motion blur, older cameras don’t have this so you’ll need a tripod for longer exposures.
Aperture: This impacts a couple of things - it will affect the depth of field of your images (how much of the image is info’s before you start to fall off into bokeh) and it will affect the sharpness of your image. Most lenses are sharpest around F/8.0 but this varies from lens to lens and you should research your lenses and learn about them so your know where the sharpest part of your lens is.
So how do you use the exposure triangle?
Well first of all, you will want to know what type of images you want to produce, then you will need to take into account the lighting conditions at the location that you are shooting at.
Let’s be clear - there are no “best settings” for a particular type of photography. I often get asked “what are the best settings for portraits” or “what are the best settings for shooting my kids football match”. The answer is “the ones you need"! This sounds flippant, but it’s true. Someone shooting a football match in bright sun, is going to need different settings to someone shooting a match under dark moody skies!
That said, there are some “givens”. If you want to freeze motion, you will need a fast shutter speed. If you want to achieve light trails at nighttime, you are going to need a longer shutter speed. If you’re trying to get motion blur in waves at the beach, you are going to want a longer speed, but then you’ll want to adapt this to the speed of the waves and the overall look that you are going for (told you this wasn’t completely straightforward!).
I could go on with this this, but what I am trying to illustrate is that you need different for different results under different conditions. You could go to the same location at the same time on two different days and need completely different settings. You can use flash to help to control the light and you can use ND filters to control the light in a different way, but that’s a whole other blog, what we’re looking at is the exposure triangle, so let’s get back on topic.
You’re going to need to use all of this information about the shot type you want to take, in conjunction with the light meter which is built into your camera’s view finder or on the display at the rear of the camera. This usually looks like a needle which moves left to right and has a number of notches along it. We’re aiming to get this right in the middle to absolutely nail the exposure. As you increase the amount of light coming into your camera, you will see this move to the right and conversely to the left as the amount of light coming into your camera decreases. We’re still aiming for the middle! This will get you get a correctly exposed image in most circumstances (if there is a lot of dynamic range (very dark areas and very bright areas in the same image) then there are ways we can deal with this, but that’s going to involve some exposure blending - more on this in another blog! For now, we’re keeping it simple.
(You will also need to consider the histogram and where on here you want to expose, but for now, we’re keeping it simple and I will come back to the histogram and how to use it in another post)
The image on the right illustrates the light-meter on your camera.
This image shows a landscape shot (some of you might recognise it!) and the light-meter can be seen at the bottom of the photo with the number -3, 2, 1 and + 1, 2, 3.
You can see the needle at the bottom indicating that the image is around 2 stops over exposed. You will also notice that parts of the image look too bright.
The shutter speed here is 4 seconds, the ISO is set to 100 we are at f/10 aperture.
Let’s go back to the original question and look at an example. Say that I am out shooting sunrise, there’s great golden hour light and I am by some water at the foot of the mountains. There’s no breeze and the lake is completely flat calm with no disturbances and there’s an awesome mountain reflection in the water. My aim here is to capture the mountains and the reflections in the water.
My thought process here is that I am going wide angle because I want a lot of the scene in my image, and I know that my wide angle lens is sharpest at F/8.0. I know that here this lens is corner-to-corner sharp. This is going to help me to set my aperture. I also know that this is going to impact the amount of light that is coming into my lens. Once my aperture is set, I can compose my shot and then check the light meter. In this situation, let’s imagine that I am getting a reading which is to the left of centre - there isn’t enough light coming into the camera to expose the image properly.
I now have a couple of choices. I can use ISO to increase my sensor’s sensitivity or I can increase my shutter speed (make it longer) to allow more time for light to hit the sensor and create the image. As you adjust both of these setting, you will start to see the light-meter moving. )Depending on your camera, you may need to half-press your shutter button to re-meter the image).
This is where we have a decision to make. I can see by looking at my camera’s settings that I am at 100 ISO. This means I have quite a bit of room before I hit my ‘limit’ of ISO 6400 on my camera (yours may be different) or I can increase my shutter speed.
I need to know that if I increase my shutter speed too much, I will need 1)a tripod to keep the camera still and 2) Anything that moves in the image such a bird flying through, an aircraft transiting the scene, or in the case of much longer exposures, clouds blowing through the image are going to create motion blur. A bird might appear unsightly and could be removed in post, cloud movement can look really cool if you want to include this, it can give a sense of time passing but this is an artistic decision for you to make based on what you want to achieve. Remember, we’re trying to shoot the reflection of the mountains so any movement in the water will also show in your long exposure, even if there isn’t much of it!
The image on the left is much darker than the previous one but is taken under the same lighting conditions.
You will see that the exposure time is much shorter, just 1/4 of a second. No other settings have changed, but the shutter is open for a much shorter amount of time, so the sensor is not exposed to the light for as long a time, which results in a darker image.
You can see that light meter is reading the left, indicating that the image is under exposed.
I could keep my original shutter speed and adjust the ISO. But I need to be aware that doing this could lead to a digital noise being introduced and could result in a grainy looking image which isn’t visually appealing. This is where knowing your camera’s limits (and your own tastes!) comes into play. If you under expose your image then increasing the exposure in post is only going to exacerbate the grain so beware!
The third option is to try and find a balance between the two. You might find the balance is between a slight increase in ISO and a slight increase in shutter speed, or that you can increase your ISO a small amount and have the option to decrease your shutter speed, allowing you to freeze more motion in the image.
Once you’re there, you can hit that shutter button and capture image! Be sure to check you have it’s all in focus and don’t just take one capture - shooting it only once, doesn’t make you a better photographer. Choice is key when it comes to making you selects and in a situation like this one, the light will be changing constantly. Always make sure to check your exposure before each shot!
As a quick aside, if you’re shooting anything which has a shutter speed of greater than your lens’s focal length, you’ll need a tripod. So if you’re on a 50mm lens and the exposure time is 1/30 then you’re going to need a tripod. If you’re on a 300mm and you’re shooting at 1/250 then you’re going to need a tripod. This will avoid motion blur and camera shake. Make sure that any image stabilisation is turned off when you are using a tripod. If you can, when using a tripod, make sure that you’re using a remote or a cable release so that you’re not introducing movement to the camera and/or lens. If you don’t have access to either of these then use your cameras self timer to ensure that the camera is completely still when the shutter actuation happens.
Let's consider another example. This time, we’re taking photos of the family dog running and we want to freeze the motion. It’s mid afternoon on an over cast day.
The key here is that we want to freeze the motion of the dog. This means we are going to need a fast shutter speed (at least 1/250) so that there is no motion blur in the image of the dog. This might be different if you have a whippet in comparison to say a bull dog; they all move at different speeds!
In this situation, I am thinking about setting my shutter speed and then taking a test shot to see where my settings have my exposure. I take the test shot (sans dog!) and can see that it is vastly underexposed, the frame is almost black (If the opposite is true, and your image is too bright and full of white areas, “blown out”, then you will need to reverse the steps below) and the exposure needle is all the way to the left of the image. Checking my camera’s other settings shows that I am at f/16 on my aperture and ISO 100.
My decision here is slightly different to what it was before, as I am now choosing between aperture and ISO. If I make my shutter speed slower then I won’t get a sharp image of my dog (let’s call him Malcolm), so I can’t change this.
The initial thought I have here is that I want to increase the size of my aperture. I know it’s at f/16 which is quite small and I know that my lens is sharpest at f/8. I make this change and the light meter shows that I am still slightly underexposed. Again, I could increase the aperture size or add some ISO. Knowing my lens, I am confident that I can move to f/5.6 and not have a massive drop in sharpness across the image and so I make this change (this drop in sharpness will depend on my distance from Malcom and in turn on his distance from the background, but I could get some great bokeh!). I can now see that my image is correctly exposed, and my ISO is still at 100. This means that I should be able to photograph Malcolm, running at full speed, and be able to see him “frozen” on the image, with no motion blur. Having ISO set at 100 also means that I know I should be getting a clean image to work with.
If when you take the shot, you find that there is motion blur, then you will need to adjust your shutter speed and make it quicker, but this means that you will also need to adjust you ISO and aperture again in order to get your image correctly exposed! You change one setting, you’re probably going to need to adjust the others.
Right - correctly exposed image.
The final shot of this image, shows the light meter indicating that we are correctly exposed. Again, the lighting hasn’t changed, aperture has remained at f/10 and the ISO is still 100.
The one thing that has changed, again, is the shutter speed. This time, you will see that it is at 1 second and this means that according to the light meter, the image is correctly exposed.
One thing that I learned quite quickly when I started out is that at times, this can be a game of compromise. An adjustment to one of the parameters, is, a lot of time going to mean that you need to adjust one of the other two in order to compensate, and knowing your camera and your lenses inside out is going to be key to you getting this right time in, time out. Getting it right matters. Getting it right means fewer shots thrown away. Getting it right consistently feels good.
Another tip which is worth bearing in mind is that you should be able to operate your camera without having to look down at the controls to find them. Most cameras are well designed in this respect and ergonomics plays a big part in how they are built, but you should know how to and be able to adjust your aperture, ISO and shutter speed without having to look for the wheels and buttons to do it with. This will save a lot of stress and time when you’re out in the field. There’s nothing worse than missing the shot because you’ve been looking down at your camera and fiddling with buttons!
If you’ve made it this far then thank you, if you’ve found it useful then please consider signing up to my mailing list to receive notifications about new blog posts, courses, workshops and offers in my print shop! If you’d like me to write about something specific, of if you have questions, then feel free to send me a message and I’ll be in touch!