What is the exposure triangle?


Exposure is a crucial element in photography that refers to the amount of light that reaches the film or image sensor of a camera. It's what determines how light or dark a photo will be, and it can have a big impact on the overall look and feel of an image. Here's a closer look at what exposure is and how it works:

  1. The exposure triangle: Exposure is controlled by three main elements: aperture, shutter speed, and ISO. These three elements make up what is known as the exposure triangle. By adjusting one or more of these elements, you can control the amount of light that enters the camera and affects the exposure of the image.
  2. Aperture: Aperture refers to the size of the opening in the lens that allows light to pass through. A larger aperture (a smaller f-number) will allow more light to enter the camera, while a smaller aperture (a larger f-number) will allow less light to enter. Aperture also affects depth of field, or the amount of an image that is in focus.
  3. Shutter speed: Shutter speed refers to the amount of time that the camera's shutter is open to allow light to reach the film or image sensor. A faster shutter speed will allow less light to enter the camera, while a slower shutter speed will allow more light to enter. Shutter speed also affects the way movement is captured in an image.
  4. ISO: ISO refers to the sensitivity of the film or image sensor to light. A higher ISO will make the film or sensor more sensitive to light, allowing for a shorter exposure time, but it can also introduce noise or grain into the image. A lower ISO will require a longer exposure time but will result in a cleaner image.


Not a perfect analogy but I like to think of a window. Imagine that the aperture of a camera is like the size of a window. Just as a larger window allows more light to enter a room, a larger aperture (a smaller f-number) allows more light to enter the camera. Similarly, a smaller window allows less light to enter a room, and a smaller aperture (a larger f-number) allows less light to enter the camera.


Next, consider the shutter speed of a camera. Imagine that the shutter speed is like the amount of time that you leave the window open. Just as a longer time with the window open allows more light to enter a room, a slower shutter speed allows more light to enter the camera. On the other hand, a shorter time with the window open allows less light to enter a room, and a faster shutter speed allows less light to enter the camera.


Finally, think about the ISO of a camera. The ISO can be compared to the type of window you are using. Some windows are better at letting in light than others - for example, a window with thin, single-paned glass will allow less light to enter a room than a window with thick, double-paned glass. Similarly, a higher ISO (a more sensitive film or image sensor) will allow more light to enter the camera, while a lower ISO (a less sensitive film or image sensor) will allow less light to enter.


If you understand how these elements work together, you can control the exposure of your images much like you would control the amount of light that enters a room through a window. By adjusting the size of the aperture, the length of the shutter speed, and the sensitivity of the ISO, you can take control of the exposure of your images and create the look and feel you want. It is also important to understand that in order to keep the exposure where you want it, when you make a change to any one of the three corners of the exposure triangle, you MUST compensate by changing at least one of the other points.


Experiment with different settings and see how they affect the exposure of your photos. With practice, you'll be able to master the art of exposure and take stunning, well-exposed photos.