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What are the 3 parts of the exposure triangle?

When you understand what each setting does and how all of them combined together can get you the right exposure, then you will manage to have full control of your camera and use it not just to take photos but create beautiful images. Read on to expose yourself to the exposure triangle.

Light sensitivity (ISO), depth of field (Aperture) and time (shutter speed) are equally important in photography. In order to get a balanced exposure, you need to adjust these settings according to the exposure triangle.

What are the 3 parts of the exposure triangle

How do you master the exposure triangle?

What is ISO

The ISO setting is the light sensitivity of the camera’s sensor. The higher the number (i.e. ISO 6400, ISO 12800), the higher the sensitivity and more noise is introduced to the image, particularly in mid-tone and shadow areas.

This happens in low light conditions especially at night when there is not enough light and we need to raise the sensitivity to make an exposure.

When our scene has enough ambient light, taking photos in lower ISO values (i.e. ISO 100, ISO 200), the shadows and highlight details are clean without showing noise, producing a better and clean image.

 ISO 200, Shutter 1/1000, Aperture F5.6

TIP: Choose lower ISO values for bright scenarios and higher ISO values when the lights go down.

What is Aperture

The Aperture setting (f) controls how much light arrives to the camera sensor by a variable opening hole that exists inside every lens. The lower f number you choose (i.e. f/1.4, f/1.8, f/2.0, etc.), the wider the aperture is and also the more depth of field is introduced.

In other words, with Aperture, we are able to specify how much of our subject stays in focus. When the Aperture number is large (i.e. f/1.8), the focus area is smaller separating the subject from the background. That creates a more shallow depth of field. Learning to create this effect in your images is why you want to expose yourself to the exposure triangle.

When you increase the f number to f/16, the focus area becomes larger including both the subject and the background to be in focus. That creates a deeper depth of field.

TIP: Choose a wider aperture of f/1.8 for portraits and smaller aperture values like f/16 for landscapes and sunsets.

What is Shutter Speed

With shutter speed you control the time when an image is taken. It is basically how much time you allow the shutter to close and take an image. You can freeze motion with higher speeds like 1/1600 sec or above, or create motion blur with lower shutter speeds like 1/8 sec.

TIP: Use high shutter speeds when you’re taking photos of sports and action and lower shutter speeds when you take photos of the stars and the Milky Way.

The Exposure Triangle and Metering

Now you know what each setting does, you need to understand how to use all three settings to make an exposure. This is what the exposure triangle is all about!

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Besides those three essential settings that are included in all cameras, there’s another feature every camera has which is called “meter”. The light around us is constantly changing. So, wherever we point our camera, it will give us a different exposure.

A meter is checking the camera settings based on where we point the camera and decides what settings we need to change for achieving a balanced exposure.

How does all work together?

Normally on the exposure triangle we set two things (i.e. Aperture and ISO or Shutter Speed and ISO) and our camera will figure out the third setting by using its meter.


  • Using Aperture priorty mode (Av) select the Aperture and ISO and the camera will figure out the Shutter Speed value
  • Using Shutter prioity mode (Tv) select the Shutter Speed and ISO and the camera will figure the correct Aperture value

Usually portrait and landscape photographers work more in Aperture priority mode and choose a low ISO because they care more about the depth of field and the light sensitivity for ultimatum quality in their images.

Sports and action photographers will usually use Shutter priority mode and set the Shutter Speed and ISO first. That’s because they do not care about the depth of field instead wanting to freezing the moment.

As a beginner photographer, you might need to experiment and adjust your settings based on what photos you’re going to get.

TIP: For better image quality, keep the ISO as low as possible. Usually in bright daylight, your ISO should be at 100 or 200 depending the camera brand you own.

Aperture and Lenses

Every lens is different and so is the Aperture on its lens. Prime lenses provide a wider Aperture while Zoom lenses use a different range. 

Here are a few examples:

  • Prime lenses use an Aperture from f/0.95 to f/22.
  • Zoom lenses with constant Aperture have a range from f/2.8 to f/22.
  • Zoom lenses with variable Aperture have a range from f/3.5-f/5.6 to f/22.

Depending on which lens you use, you’re limited to the Aperture it provides. Usually, lenses with wider aperture (i.e. f/1.4 or f/1.2) are more expensive. Those can give you a very shallow depth of field; they’re very sharp and produce outstanding image quality.


Now that you have read “expose yourself to the exposure triangle”, you will be able to create well exposed images.

It might take a lot of time, practice, trial and error but the moment you realize how to change the settings and maintain a good exposure, your thinking on photography will take a whole different meaning.

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Jason Baxter

Jason is a professional photographer based in Stillwater, Oklahoma. Loyd has been doing photography for over 14 years and specializes in fine art landscape photography. Loyd's work has appeared on book covers, CD covers, television, internet galleries, and on the walls of private residences.