The Exposure Triangle: ISO, Aperture, and Shutter Speed

by | Nov 16, 2021

photography - exposure triangle

Good photography takes skill. It involves a lot more practice and knowledge than people realize. If you’re at the point where you want to take full control of your camera to capture those “talented! brilliant! incredible! amazing! show stopping! spectacular!” photos like Lady Gaga would say, you’ve come to the right place. In this blog, we’ll cover the three major factors of achieving the correct exposure of images in manual settings. These three factors are ISO, aperture, and shutter speed. Together, they are known as “The Exposure Triangle.”


The Exposure Triangle


Factor 1: ISO 

The first factor is ISO, which is the sensitivity level of your camera’s sensor. Every camera has a range of ISO values and each will impact the quality of your photos. The lowest value is typically around ISO 100 and the values will double in range as you increase, so the next would be ISO 200, 400, 800, 1600, 3200, etc. 

To explain, a lower ISO value (like ISO 100) means less sensitivity to light, so it will darken the image. You’d likely use ISO 100 if you’re shooting outdoors on a bright and sunny day. Since there’s so much light around you already, your camera’s level sensor doesn’t need to be exposed to as much light. If the lighting is right, you can get a nice, crisp photo using a low ISO.

On the other hand, a higher ISO value (like ISO 3200) means more sensitivity to light, so it will brighten an image. You’d likely use ISO 3200 if you’re shooting at a dimly light concert or at night. Since you’re in a darker space, your camera’s level sensor will need to be more exposed to catch more light. The catch here is that the higher the ISO value, the more grainy the photo will get. Each increase in ISO value results in a decrease in photo quality. If you’re shooting for a client, you have to be careful to not use too high of an ISO because it will lower the quality of the photo — instead, try adjusting your aperture and shutter speed to keep the ISO lower.


Factor 2: Aperture

The second factor of getting correct exposure is aperture. Aperture is the size of the hole in your lens that lets light into your camera. This concept can be thought of in the same sense as your eyes. The iris in your eye either expands or shrinks depending on how light or dark it is — this controls the size of your pupil. The “pupil” of your camera lens is the aperture. With aperture, you can control how much light reaches your camera sensor by enlarging or shrinking it. 

Apertures are measured in “F-stops” on your camera. A small F-stop number (like F2) will enlarge the aperture hole, which lets more light pass through the lens. A large F-stop number (like F22) will shrink the aperture, which lets less light pass through the lens. Think of F-stops and the size of the hole as being opposites — smaller number, more light or larger number, less light. 

Not only do apertures determine the light exposure of your images, but they also can add a beautiful dimension to your photo. With a larger aperture, you can create a shallow depth of field. This would be great for focusing on a close-up subject and having a blurred background. On the other end of the spectrum, a small aperture creates a large depth of field. This would be great for a stunning landscape photo focusing on both the near foreground and the horizon.


Factor 3: Shutter Speed

The third and final factor is shutter speed. The shutter speed is the amount of time you expose light to your sensor. Shutter speed works exactly how you think it would. The longer your shutter speed, the more light that comes in. The shorter your shutter speed, the less light that comes in. A fast shutter speed freezes the motions in your image. You’d likely want to use a fast shutter speed ( like 1/1000 of a second) to freeze athletes in motion or children playing in bright light. A slow shutter speed blurs the motions in your image and is typically used in low-light settings. If you’ve ever seen photos of busy city streets with the car lights slurred across the road or a serene waterfall that, quite literally, looks like it’s flowing through the image — that’s the magic of shutter speed. For those two scenarios, you’d need to use a very slow shutter speed (like one second) and a tripod (you CAN’T forget the tripod when using slow shutter speed). A tripod is necessary when using a slow shutter because it allows you to have a still background and ensures that your details remain crisp. If you hold your camera while using a slow shutter, everything will be blurry from the camera shake. 


Closing Thoughts

The three factors of The Exposure Triangle — ISO, aperture, and shutter speed — all work together to determine exposure. It’s a constant tradeoff between the three, meaning that if you change one factor, you’ll need to change another to make up for the difference. The best place to start is just by practicing with your camera in manual mode. Find different scenarios and adjust your settings accordingly to get a correctly exposed photo. The more you practice, the faster you’ll be at adjusting the settings, and the better your photos will look. It takes time and patience, but it’ll surely get you closer to getting that million-dollar shot!

Transformation Marketing is a marketing agency located near Lincoln, NE. Not only do we specialize in photography and videography but also social media management, graphic design, website development, programmatic advertising, and much more. To learn more about TM, give us a call at 402-788-2896!

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