Important Knowledge You Need To Know About Aperture

Aperture is one of the three elements that make up the exposure triangle in photography. Understanding how it works and what settings to use in different situations is crucial to taking quality photographs. In this article, we look at Important Knowledge You Need To Know About Aperture to help you improve the quality of your work.

1. What is Aperture In Photography?

The definition of an aperture is “An opening, hole, or gap”. Aperture in photography refers to the opening inside the lens of a camera. Controlling this opening is a series of mechanical blades called a diaphragm that increases or decreases the size of the hole.

A helpful analogy is to think of this mechanism as the iris of a human eye. When wide open, the iris allows more light to enter the eye. Conversely, when an iris is narrow, it exposes the eye’s retina to less. This concept is precisely the same as the inner workings of the aperture of a camera. However, it is the camera’s sensor or film that is exposed instead of the retina.

2. How Is Aperture Measured?

Expressed as a fraction aperture in photography is measured in f-stops. It may seem counterintuitive, but the higher the f-stop number is, the smaller the opening in the lens will be. This measurement makes more sense when you remember how fractions work. For example, one half 1/2 is more than one quarter 1/4. The number is smaller, but it equates to more quantity. 

Lenses come in a variety of f-stop ranges. However, the most common are:

  • f/2
  • f/2.8
  • f/4
  • f/5.6
  • f/8
  • f/11
  • f/16
  • f/22

3. What Is An F-Stop?

An f-stop is a mathematical relationship between your camera focal length and the size of your aperture.

Focal length / Diameter of aperture = f-stop

The f in f-stop stands for focal length. To summarise, the crucial thing to take away is that the f-stop is simply the diameter of the hole created by the aperture blades in your lens.

For example, if you were using a focal length of 80mm and set the aperture to f/4, the diameter of the hole will result in a 20mm measurement. This result is because one-quarter of 80 is 20. Whereas at f/16, the width would be 5mm.

4. Aperture And Exposure

Because the size of the aperture has a direct correlation to the amount of light that is permitted to enter the camera, it has a direct relation to the exposure value of a photograph. If the ISO and shutter speed settings were kept the same, opening or closing the aperture will result in a brighter or darker image.

Large apertures such as f/1.4 are known as “fast apertures” because they permit higher shutter speeds. You may hear of lenses with wider than average aperture settings referred to as “fast lenses”. These lenses are suited best to low light conditions and portraiture.

5. Aperture And Depth Of Field

The size of a camera’s aperture shares a direct relationship with the sharpness and depth of field in a photograph. In other words, how blurry an image will be.

When a camera has a wider aperture, less of an image will be in focus. Think of portrait photography where the subject is sharp, but the background is blurry. This effect also increases the illusion of space between objects in an image and is why a photograph shot with a wide aperture is said to have a greater depth of field.

Conversely, when a camera has a narrower aperture, more of a composition will be in focus. Landscape photography uses high f-stops to ensure everything in a frame is sharp.

6. Aperture And Sharpness

The aperture used can have a direct result in the sharpness of photographs. A loss of detail will occur when the f-stop is widened or narrowed to the extremes. This effect can occur at different f-stops with different lenses.

Generally speaking, a photograph will begin to lose its sharpness when the aperture ring opens beyond f/5.6. At this end, a lens will struggle to focus on everything, especially around the edges of an image that will warp and become fuzzy. Conversely, the phenomenon of diffraction occurs when an f-stop is beyond f/16.

As a rule, the sweet spot of a lens is typically two to 3 stops below its widest aperture. For example, if the lens has a maximum aperture of f/4, the sweet spot will be between f/8 and f/11. This spot will vary between lenses. The best way to find out where yours is will be to take multiple photographs of the same scene taken from a tripod and examine the details in them on a computer screen.

7. The Best Aperture Settings

There are no right and wrong aperture settings. However, using certain f-stops will increase the quality of your photographs depending on what you are shooting.

7.1. Night and low-light Photography – f/1.4 – f/5.6

Night sky - Important Knowledge You Need To Know About Aperture

When shooting at night, a camera will need a larger aperture to gather as much light as possible to expose it to the sensor. This rule is especially true if you are shooting handheld and freezing moving subjects.

7.2. Wildlife Photography – f/1.4 – f/8

Geese - Important Knowledge You Need To Know About Aperture

The aperture needed in wildlife photography will vary depending on the subjects you photograph and the depth of field you wish to achieve.

When shooting things like flying birds, a wide aperture will be required to increase the shutter speed. Whereas when shooting a slower moving subject, a narrower f-stop will suffice. This choice can help retain more environmental details.

7.3. Portraiture Photography – f/1.4 – f/8

Portrait - Important Knowledge You Need To Know About Aperture

Most of the time, portraiture photography aims to isolate the subject from the background. This effect helps to draw a viewer’s gaze into the face and eyes of a person. However, sometimes a backdrop can be a helpful element to tell a story about the person and the environment in which they are interacting. In this case, a narrower aperture is a better choice. Just not so small, the entire composition becomes focused. With portraiture, it is vital to keep the person as the focal point of an image.

7.4. Group Photography

Group of people

When shooting group photographs, it is crucial to capture the entire group in focus. This reason means the lower f-stop numbers used in portraiture are not suited to group photography. The f-stop required will vary depending on the size of the group and the space between the subjects.

7.5. Landscape Photography (No Foreground) – f/8 – f/11


When shooting landscapes with no foreground, the aperture can be set narrower than in landscapes with a foreground. This reason is due to the camera not needing to flatten out a greater depth of field in the composition.

7.6 Landscapes (with foreground) – f/11 – f/16


When shooting landscapes with foregrounds, it is necessary to stretch the aperture to its limits of narrowness. This setting is required because all of the elements in the composition must be flattened and in focus.

8. Conclusion

Understanding what aperture settings to use is a vital necessity in photography. Besides making sure the photographs are sharp and in focus, it also has the power to emphasise things such as storytelling in your images.

The best way to learn is by doing, so you should set yourself the assignment to get into the field and photograph each of the categories mentioned in this article. This way, you will understand first-hand how the aperture setting relates to how a photograph is exposed.

Important Knowledge You Need To Know About Aperture, Important Knowledge You Need To Know About Aperture, Important Knowledge You Need To Know About Aperture.

David Davis
David Davis
Hi, My name is Dave, and I am passionate about photography. I am currently travelling to document the world's most interesting people and places. I have started this blog to share these incredible sights and experiences with you, including all the knowledge I gain as a photographer/videographer along the way. If you share a passion for street, documentary, and travel photography, join the mailing list and stay up to date with the latest posts and resources direct from the field.

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