Mastering Light In Photography: The Exposure Triangle

Automatic exposure modes alleviate the pressure of “calculating” the exposure of your images. However, they can often leave you with undesired results in tricky lighting situations. Manual exposure is essential for any photographer looking to truly harness the power of light. Contrary to popular belief—it’s easy too!

Photo by Iván Levyv on Unsplash

In this article we discuss how to manually expose your images.

This is part three of our four-part article series on understanding light. You can find the rest of the series here:

Contents

  1. Exposing Light: The Exposure Triangle
    • A. ISO
    • B. Shutter Speed
    • C. Aperture

The Exposure Triangle

Our eyes naturally interpret incoming light and “re-expose” our eyes so that we can see adequately. Our eyes do this so rapidly and with such efficiency that it’s rare we run into issues. Though you may have experienced your eyes re-adjusting in sudden and drastic changes of light such as walking from a dark room into bright sunlight.

Photo by Amanda Dalbjörn on Unsplash

Camera technology is not as sophisticated as our eyesight. It relies on three elements working together to produce a certain exposure. These three elements are commonly referred to as the “exposure triangle”.

  1. ISO
  2. Shutter Speed
  3. Aperture
An excellent resource by Daniel Peter of Fotoblog Hamburg. Download the free resource here.
This resource is explained throughout this article.

You may be used to your camera automatically determining your exposure, similarly to your eye. In order to do this, cameras rely on something known as a “light meter” which then determines the “best” combination of ISO, shutter speed and aperture for that specific light.

Built-in camera light meters can often misinterpret light, especially in tricky light scenarios. This is why it is imperative for photographers to understand the exposure triangle and how it impacts their images.

Exposure Triangle: ISO

ISO refers to the camera sensor’s sensitivity to light. The higher the ISO, the more sensitive your camera is to incoming light.

It varies between camera models but ISO is usually measured in numbers such as: 100, 200, 400 and so on.

As your ISO is increased, the appearance of what’s known as “noise” will also increase. This noise is often unwanted and can distract away from an image or reduce its overall quality. For this reason, photographers will typically opt for the lowest ISO setting possible.

Portion of cheat sheet by Daniel Peter of Fotoblog Hamburg. Download the free resource here.

Exposure Triangle: Shutter Speed

Shutter speed refers to the length of time the sensor is exposed to light. The longer the sensor is exposed to light, the brighter the exposure will be.

Shutter speed is measured in fractions of seconds, such as 1/500, until you reach 1s exposure time. From there, shutter speed will incrementally increase up to 30s exposure and then a “bulb” mode which allows you to take exposures much longer than 30s.

Shutter speed has a direct effect on the way that motion appears in your image. Shorter exposure times, also known as fast shutter speeds, will freeze motion. Longer exposure times, also known as slow shutter speeds, will blur motion.

Portion of cheat sheet by Daniel Peter of Fotoblog Hamburg. Download the free resource here.

Exposure Triangle: Aperture

Aperture refers to the diameter of a lens’ opening that light passes through onto the camera’s sensor. The larger the opening, the more light that travels through the lens which results in a brighter exposure.

Aperture is measured in “f-stops” and commonly written as: f/4. This measurement is essentially just a fraction that refers to how wide that opening in the lens is. An f-stop of f/2 is 1/2 open. Using this logic, f/2 is more open than f/8.

Aperture has a direct effect on depth of field. “Larger” f-stops, like f/1.4, have a “shallow” depth of field. This means that only a small area surrounding the focus point will be in focus with the rest of the image out of focus or blurred. “Smaller” f-stops, like f/16, will have a “deep” depth of field. This means that a larger amount of the image surrounding the focus point will be in focus.

Portion of cheat sheet by Daniel Peter of Fotoblog Hamburg. Download the free resource here.

Creative ways to use the exposure triangle

The exposure triangle’s primary function is to control the exposure of your image. However, the effects of ISO, aperture and shutter speed can be used as a creative tool. Here are some ideas:

  • Experiment with light painting through long exposures
  • Freeze motion with a fast shutter speed
  • Use a large aperture to create blurry bokeh

Getting Started

Light is a complicated topic that deserves a thorough study as a photographer. It is, after all, the primary resource when creating images.

This article is part three in a four-part series that further explores light in photography. You can find the rest of the series here:

As you move forward in your photography, challenge yourself to expose your images manually. What differences do you see in your photography? Let us know in the comments below.

Leave a Reply

Your email address will not be published. Required fields are marked *