What exactly is exposure triangle? You have stumbled upon this article possibly because of your interest to learn photography. Another possible reason is that you are trying to make sense of these terminologies you heard from someone. Nevertheless, the term “exposure” shouldn’t be as confusing as it sounds.

Exposure Triangle and its three elements

As you know, a photograph is the delicate balance of Aperture, Shutter Speed, and ISO. These elements emphasize the aesthetic, style, and make an of an image. Timing, depth of field (DOF), and light sensitivity also tie-in with these terms. To balance these components, you must understand the relationship between them to best present your subject.

Now let’s begin with Aperture.

Aperture, also called the F-stop, is the equivalent of the eye's iris in human anatomy. It is the size of the hole that allows light in the camera. More so than just controlling how much light hits the camera's sensor, the aperture also controls how much of the scene is getting focus  In photography, this refers to depth of field. Depth of field points to how much area a photo has a sharp or acceptable focus.

In a  camera, lower to higher F-stops (F2, F11, F22, etc.) represent the aperture. A wider aperture is a smaller F-number on your camera. Whereas, a narrower aperture is a higher F-number.

Shooting at a larger aperture like F1.8 creates a very narrow area of focus while stopping the aperture down to F11 gives a greater depth of field with more of the subject and background in focus. A larger F-stop would result in a more shallow depth of field, and the smaller F-stop produces images with an overall focus.

Up next is a component we call Shutter Speed.

Shutter Speed, measured in seconds, is the moment between the opening and closing of the camera shutter. Following the human anatomy analogy, eyelids are equivalent to the camera shutter, and the rate at which the eyelids open and close is the shutter speed.

The faster the shutter speed is, the less time to collect the light. The slower it is, the more time for the sensor to receive more light. Not just limited to light, it also affects how much motion or movement will be in an image. The faster the shutter speed, the higher the chance you can freeze action while a slower the shutter speed gives the opposite effect, and the more likely you are to blur the motion. 

Both shutter speed and aperture make use of stops.  In shutter speed, a decrease of one-stop is equal to twice the length of time the shutter is open, while in aperture, a drop of one-stop is equal to half an increase in the size of the shutter opening. To note, the first two components are very much basics that one should understand when properly photographing a scene.

Both shutter speed and aperture make use of stops.  In shutter speed, a decrease of one-stop is equal to twice the length of time the shutter is open. In aperture, a drop of one-stop is equal to half an increase in the size of the shutter opening. To note, the first two components are very much basics that one should understand when properly photographing a scene.

The third one is the ISO.

ISO is more like a compensation component though equally important. Completing the exposure trinity, ISO refers to the light sensitivity of the film or sensor. Keeping on with the analogy, ISO is like your eyes when you go to a dark theater. At first, it is difficult to see, but as the eyes adjust to the environment, then one can see better. In your camera, ISO presents itself in a system of numbers ranging from 50, 100, 200, and higher. A higher ISO equates to increased light sensitivity resulting in a higher exposure while the opposite, a smaller ISO, means decreased light sensitivity resulting in lower exposure. 

Important to note that there is a penalty in increasing the ISO; it results in increased noise or perceptible grain in the photograph, thereby reducing the quality of the image. Which is why ISO is considered a residual adjustment after setting the Aperture and Shutter Speed.

Completing the Exposure Triangle

Aperture, Shutter Speed, and ISO are equally essential to get the perfect exposure, obtain creative control, and tell a better story. Each element is a complement of the other to generate an exposure value. This means that manipulating one item would have a corresponding impact on a different aspect, and this where the Exposure Triangle comes in to help.

You may use the Triangle as a guide or a crutch in your quest to become the ultimate photographer. It is by far, the best visual representation of how these three elements affect each other.

Each corner of the triangle represents a variable, and the trick is balancing the settings to get the perfect image.

Now the question is, why are there three controls to assist with the excellent exposure? Wouldn't one suffice? The answer is NO. As I eloquently explained in the course of this article, it takes three to tango. Think of their relationships like cogs. When one moves, the other two move with them (to expose the scene properly).

Examples

Take the example below; all instances generate the same exposure value but produce a slightly different result.

• The first example offers a reasonable DOF (in relation to Aperture) but with some risk of visual noise (because of high ISO).

• The second example widened the aperture to F4, which means the shutter can be open for less time, producing an image that captures an action (high shutter speed).

• For the last case, a slow shutter speed means a smaller aperture (for a deeper DOF). It also gives a motion feel to an image (slower shutter speed).

Conclusion

Ultimately, there are several ways to get a preferable exposure. The combination still depends on the look you want to achieve. With that in mind, know that there is no shortcut in understanding exposure. The key is to play with the settings until you get the image that matches your vision–plus practice.

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