What is Exposure Triangle?

If you are just starting in photography and want to learn how to control exposure, let us help you. The first question that you probably have in mind is ‘What is Exposure Triangle’. It is a technique used to better expose the image using three different variables. Read along to understand it in detail.

What is Exposure Triangle?

The very first thing that you need to understand about exposure is that it is controlled by the amount of light. That light can either be the natural ambient light or even the artificial light produced in a studio. In digital photography, what happens is that the amount of light entering a camera and the sensitivity of the camera to that light dictate the exposure of the photograph. Unfortunately, you cannot control the intensity, direction, or sometimes even the distance from the light source. So, if light controls the exposure, how do we adjust it? The answer is simple, by using the exposure triangle. As the name suggests, the exposure triangle is composed of three different settings which are aperture, shutter speed, and ISO. In order to understand the exposure triangle and its function, it is important to discuss these three variables first.


Aperture is the opening through which the light passes and reaches the lens. Therefore, if that opening or hole is bigger, more light will pass through it. On the other hand, if that hole is smaller, less light will pass. In terms of a digital camera, you might recognize it by f-stop. It is a ratio that is directly affected by the opening. So, if you were to increase the exposure by one stop, it would mean that you have doubled the light entering through the hole and vice versa. Therefore, in simple words, aperture controls the amount of light entering the camera.
Camera settings of Exposure Triangle

Photo edited in Lightroom.

Shutter Speed

Now, moving on to shutter speed, it can be defined as the measurement of time in which the light is allowed to reach the sensor. Basically, the longer the shutter remains open, the more the light reaches the sensor or film. Whereas, if we keep the duration short, then it will allow lesser light to pass through. Another way to understand it is that whenever you press the shutter button, a door closes and an image is taken. If you were to change its speed from 1s to 1/2s, then it would practically mean that you just cut the amount of light entering in half.


Lastly, understanding ISO is important to fully understand the answer of what is exposure triangle. Unlike the other two variables which are focused on the light entering a camera, ISO is focused on the sensitivity of the camera to that light. To keep it simple, if you use a low ISO, it will mean that the sensitivity of the digital sensor or film is also low and you will need more light to capture the image. However, if you are working in low-light conditions, using a higher ISO value will increase the sensitivity. Therefore, you will be able to capture better images even in low light.

How does the Exposure Triangle Work?

Up until now, we have only answered what is exposure triangle. However, understanding it is not enough. You also need to know how you could use it to get better images. An important point to realize is that all three variables of the exposure triangle affect each other directly. Before we talk about their relation, it is equally important to understand their effect on the output image. First of all, aperture controls the depth of field or the bokeh effect. If it is smaller, the depth of field is also smaller and vice versa. Next, shutter speed can freeze action in motion or even blur that action. Lastly, if you increase ISO, you can take better images in dark but it will also add some noise or grain to your image. Now if you understand their effect, then it is time to understand their combined effect for better understanding the exposure triangle. For instance, if you were to decrease the shutter speed. It would mean that the time for the light to enter has decreased. Therefore, you either need to adjust aperture or ISO (or both). Doing this will help you get proper exposure even with low shutter speed.
Man changing camera settings - What is exposure triangle

Photo edited in Lightroom.

Aperture and Shutter Priority Modes

Camera manufacturers understand that it might be a little overwhelming to properly understand what is exposure triangle for beginners. Therefore, they have added these priority modes to help you. As the name suggests, in the Aperture Priority Mode, you have to adjust the value of aperture and the camera takes care of the shutter speed itself. Similarly, in Shutter Priority Mode, you only control Shutter Speed and the camera adjusts the value of Aperture.

Conclusion - What is Exposure Triangle?

To sum it all up, aperture, shutter speed, and ISO are the answer to what is exposure triangle. You basically need to determine what the adjustment of a single value does to the whole image. Only after that, you will be able to freely control the exposure of your images. 

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Have a nice photoshoot! 

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