The Exposure Triangle: What Is It and How does it Work?

Photographers use a lot of weird terms and phrases that can be hard to understand. And one of those terms is the exposure triangle. What is it? And do you actually need to know about it? These were questions my friend, Ween, asked me as we headed outside to take some photos. The exposure triangle is basically what makes photography and your camera work, so it’s really important and you definitely need to know about it! Photography is all about light, and the exposure triangle is essentially how your camera reacts to light.

This is the first photo Ween took before she even knew about changing the settings on a camera. Photo by: Nguyen Pham

This post is going to include pictures that Ween took throughout the time we were practicing. They will showcase her progress and understanding as I explained the 3 elements of the exposure triangle. The explanations in here are assuming that your camera is in manual mode.

ISO

ISO is all about how sensitive your camera’s sensor is to light. When your ISO is higher (like 1600) your camera is more sensitive to light, which means it is bringing in all the light around it so that it can take photos in a low light situation. When your ISO is lower (like 100 or 200) it means your camera is less sensitive to light and you need much less light to get a good photo. Generally if you are outside during the day a lower ISO will work just great. While having a high ISO that can take photos in low light situations seems great, it isn’t always the best option. Clarity is affected. When you use a high ISO your photos will be grainy or have lots of “noise” So unless that is the look you are going for, generally, the lowest ISO you can use is the best. Ween caught onto ISO pretty easily. She said that it was easy to remember. I told her that when I am shooting, I prefer to set my ISO first because I know that I want it to be as low as possible, and also because unless your lighting conditions are changing a lot, your ISO probably won’t change while you’re out taking photos

The easiest way to explain this to Ween was to tell her to think about the next two elements in terms of an eye.

Aperture

Think of aperture like the camera’s pupil. Your pupil is the black part in the middle of your eye. When you are in a dark place with not a lot of light your pupil gets bigger to let in more light. And when you are in a bright place your pupil gets smaller to let less light in so that you aren’t blinded. Your camera does the same thing. When you have a low f-stop (f/2.8, think low light) it means your camera’s pupil is really big and lets in lots of light. When the f-stop is high (f/16, think lots of light) your camera’s pupil is small and limits how much light will get in. Another aspect of aperture is depth of field. When you have a low f-stop, or a wide aperture, you will also get a shallow depth of field. A shallow depth of field is when your subject is in really good focus but the background is all blurry.

Ween took this photo to test out the idea of a shallow depth of field. She wanted the tip of the branch to be in sharp focus while the background was all blurry. Photo by: Nguyen Pham

At first Ween was a little confused about the depth of field and what it meant. But I explained to her that nature photographs and portraits use a shallow depth of field to make sure the focus is entirely on their subject. After a little more explanation she got it. I let her know that after setting my ISO I like to change my aperture to what I want it to be. If I’m taking a portrait I know that I’ll want a lower f-stop, so I just get that set right after ISO.

Shutter Speed

Shutter speed is like your camera’s eyelid. The faster the shutter the faster the eyelid is blinking. When you open your eyes for a long time (like 10 seconds) you can see movement happening. But when you blink really quick all movement is frozen and you only see a quick little snapshot of the scene around you. That’s how shutter speed works too! When you have a slow shutter speed (like 1 second) that means your camera isn’t “blinking” for a whole second (or whatever it’s set to) and it’s bringing in lots of light, so it can “see” lots of motion! But that motion shows up as blur in your photos.

When you have a short shutter speed (1/800 of a second) that means your camera just blinks once real quick and doesn't let in a lot of light. This freezes motion in the way that we all appreciate from photographs. Freezing motion is really cool (think water drops from a faucet or a bird flying through the sky), but because your camera’s eye isn’t open for very long you need to have lots of light in order to use a shorter shutter speed.

Ween wanted to test out shutter speed. So she took this photo at a shutter speed slower than 1/60. This caused her picture to be blurry! Photo by: Nguyen Pham

Ween thought this one made a lot of sense and started playing around with it. But I quickly had to give her the rule of thumb. The rule of thumb with shutter speed is that you don’t shoot handheld (or without a tripod) at any shutter speed slower than 1/60. Our bodies naturally move, and movement causes camera shake. And although there are things you can do to help prevent camera shake, following this rule of thumb will help out a lot!

I prefer to set my shutter speed last. If you mainly take sports photos or like taking photos of birds you may want to set this one earlier and change the other settings after. But for me, I generally take portraits, which means my subjects aren’t moving much. That means that as long as my shutter speed isn’t slower than 1/60, I'm generally okay with any shutter speed setting.

Metering

After telling Ween all of this and letting her practice changing each setting she was still a little confused about what it meant and how she needed to use the information. This is where I explained what a meter is and how to read one. The meter in your camera tells you the exposure of the photo you’re going to take based on your camera’s settings. Exposure is really just how light or dark your photo is. And when looking at a meter, a - means under exposed (dark), a + means over exposed (bright), and a 0 means correctly exposed. When you point your camera toward the area you are going to take a photo, your camera’s meter will tell you what your exposure is going to be with the current camera settings you have. The meter can be found when you look through the viewfinder or on the screen. If the tick mark is towards the - or + you’ll need to change your settings to get it close to 0.

This is the last picture Ween took after learning all about the exposure triangle. Even though it takes lots of time and practice, she learned a lot and made tons of progress just by practicing for like an hour! Photo by: Nguyen Pham

Learning about the exposure triangle and how it all works together can seem really intimidating! When I first started trying to learn I felt like I would never figure it out!. And I still have a long way to go and so much more to learn. But even by the end of our hour of practicing, Ween was so much better than when we had started! And the more you practice, the easier it will become and the more you will remember.

What intimidates you the most about switching your camera into manual mode?