What is Aperture in Photography? A Beginner’s Guide

Confused about where to start in photography but want those cool Bokeh and Sunstar effects? Well, understanding aperture will help you learn all of that along with many more!

Aperture is one of the pillars in photography and it can quite literally make or break a picture. Even professionals tend to face difficulty with utilizing aperture, hence it’s normal if you’re not aware of it!

So, what is aperture in photography really? In this article, you will learn everything about aperture in the simplest manner possible. Whether you are a beginner, a hobbyist, a professional – this guide will be useful for all.

What is Aperture?

Aperture is a feature of the camera’s lens, not the camera body. It refers to the size of the opening through which external light passes, and then into the camera’s sensor.

What is Aperture

Aperture is expressed as a fraction – f/d. “f” is the focal length of the lens, while “d” is the diameter of the entrance pupil of the lens. However, in photography we always keep f as f because the focal length stays the same when you adjust aperture. It’s just the diameter that changes.

In other words, a higher f-number (f/8) means lower aperture. A lower f-number means higher aperture (f/1.4).

Each change in f-number is referred to f-stops, and instead of saying “increasing/decreasing aperture” we can also say “stop up/stop down”, respectively.

What Does Aperture Do to Your Photos?

Aperture simply increases or reduces how much light is being accepted by your camera’s lens. However, this simple change can make drastic changes to a photo. These are the lists of things which are directly linked to aperture.

  • Exposure / brightness
  • Depth of field / focus
  • Effects like bokeh, starburst and sunstar
  • Unwanted micro elements in photo

We will discuss these things below. First, let’s learn how to change the aperture first!

How to Set Camera Aperture

There are three ways in which you can set a camera’s aperture.

  1. Aperture Priority (A or Av) mode
  2. Manual (M) mode
  3. AUTO (Auto, A or A+) mode.
Aperture Setting

Aperture Priority Mode

In aperture priority mode, the camera’s ISO and shutter speed is selected automatically according to the aperture you use.

To enable aperture priority mode,

  1. Rotate the mode selector (a circular dial on the top left or right on the camera’s body) to shutter priority (A or Av) mode.
  2. Select the aperture using the camera’s selector buttons.

Nikon and Sony use an “A” symbol for this mode, while Canon and Pentax use an “Av” symbol. If you have other brands, the symbol will be listed in the camera’s manual.

Manual Mode

In manual mode the aperture, shutter speed and ISO are all selected manually by you.

To enable manual mode,

  1. Rotate the mode selector (a circular dial on the top left or right on the camera’s body) to Manual (M) mode.
  2. Select the aperture, shutter speed and ISO using the camera’s selector buttons.

Use manual mode if you have the scope to learn about other exposure values like ISO and shutter speed through some study and experimentation or you already know how these settings work.

Auto Mode

In auto mode, the camera decides aperture, ISO and shutter speed for you. This mode is great if you want to take pictures spontaneously, without changing settings after each snap.

To enable auto mode,

  1. Rotate the mode selector (a circular dial on the top left or right on the camera’s body) to auto (Auto, A or A+) mode.
  2. In some cameras, the auto mode can be selected through the Program (P) mode.

Although the pictures in AUTO mode will be great, learning to use Aperture priority or Manual mode will enable you to take even better photos!

What Are the Uses of Different Apertures?

Now that you have learnt how to change aperture in all the possible ways, let us understand the practical uses of different apertures.

How Aperture Affects Exposure

The first concern of an image is it’s brightness. As a photographer, it’s important to ensure that your image is well illuminated.

Increasing the aperture increases exposure and vice versa. However, in many cases you might need to change the aperture without affecting the exposure.

Aperture and Exposure

Nothing to worry, as you can change the aperture while keeping the exposure intact through Aperture Priority or Manual mode.

In Manual mode, you can maintain the exposure by changing ISO and shutter speed. In aperture priority mode, it’s much easier as the camera sets everything else automatically as you change the aperture.

How Aperture Affects Depth of Field

The relationship between aperture and depth of field is one of the most important in photography.

Depth of field is the area of an image which is in focus and sharp enough to be acceptable by the human eye. In photography, this particular area of focus is referred to as the focus plane.

Aperture and Depth of Field

Aperture and depth of field affects-

  1. Whether your subject is in or out of the focus plane
  2. How many subjects and how much of each subject is inside the focus plane

This area of this focus plane is typically wall-shaped, parallel to the camera’s lenses. Unless you’re using special lenses like tilt-shift lenses, the focus plane will always be parallel.

How thick or thin this focus plane is the depth of field. A thin/shallow depth of field will make the image look a certain way, while a thick/deep depth of field will make it look another way.

Thick Depth of Field vs Shallow Depth of Field

Increasing the f-numbers reduces the aperture. This reduced aperture results in a thicker depth of field. Decreasing the f-numbers do the exact opposite, and makes a thinner depth of field.

A thicker depth of field results in more of the image being in focus and sharp. This is great for landscape shots or any other shots with a wide angle of view.

For portraits, a thinner depth of field looks more professional, because a blurred background puts more emphasis on the subject(s). However, this is completely up to your environment and preference, so do experiment with different aperture settings.

Focal Length and Depth of field

The focal length of your lens also determines your depth of field. A longer focal length will result in a thinner, shallower depth of field.

Hence, if you need an incredibly thin depth of field, use a lens with a very long focal length. Or if you need a very deep depth of field, use a lens with small focal length.

Bokeh, Starburst and Sunstar effects

Aperture is one of the things which make creative effects like bokeh and starburst possible right from the camera! Let’s understand how you can easily achieve them.


Bokeh is one of the most popular photography techniques, acclaimed by professionals and beginners around the globe. All you need to do for this effect is find appropriate lighting and adjust the aperture accordingly.

Bokeh Effect

To achieve this, reduce the f-numbers to the lowest possible value. This increases the aperture and blurs out the background into small dots.

If you want to include a subject inside the focus plane with this effect, you can! The depth of field is very shallow when the aperture is increased to the max, so keep moving your camera/subject back and forth until the subject comes into focus.

However, you will need a lens with a minimum f-stop of f/2.8 or lower. The bokeh effect isn’t quite achievable with lenses that do not have f-stops lower than this.

Sunstar and Starburst

This is a beautiful effect which can be achieved quite easily. Opposite to bokeh, you will need to increase the f-stops to the maximum possible value.

This high f-number decreases the aperture, making any light sources appear in a multi-edged star shape. Thus, lenses with very high f stops (f/8 or higher) will give you better starbursts.

For this effect, the light sources need to be very bright and preferably from single points. The sun or bright street lamps work well for this effect.

Just make sure you adjust the ISO and shutter speed accordingly, and that you don’t point directly at these light sources.

Even if you do point directly at them, you could use any foreground objects to dim the light. A common trick is to shoot the sun before dusk, when luminosity is relatively low.

Unwanted Micro Elements in Photo

Aperture can affect how certain minor elements appear in the image. These can be omitted if you understand them correctly. They are –


Why don’t all photographers increase their f-numbers to the max to just get everything in focus? I mean, you could also blur the background during photography post processing, right?

Not that easy. Whilst increasing f-stops does put everything in focus, it also affects the sharpness and resolution. When you zoom into the image, the image will appear less sharper compared to a picture with lower f-stop.

Why is that? Well, increasing the f-stop decreases the aperture, shrinking the lens’ opening. Through such a small opening, not enough light passes through to fully capture the micro details of a frame. This effect is called diffraction.

The bigger the aperture is, the more light and micro-information the lens can receive, resulting in a sharper image.

Lens Aberration

Much like diffraction, lens aberration is an undesirable effect. Spherical aberration, distortion, vignetting, field curvature, astigmatism, coma, color fringing are all results of lens’ aberration. You do not really need to know about these in detail.

All you need to be aware of is whether the picture looks the way you’re intending it to. If not, changing the aperture can reduce lens aberration. However, there is no fixed rule so in some cases you’ll have to increase the aperture, or in some cases you’ll have to decrease it in order to get it right.

Dust or Lint

It’s possible that a speck of dust falls on the surface of your lens while you’re shooting outdoors. No matter how much you clean your lens, dust or lint occur naturally in the atmosphere, especially outdoors.

It’s not an issue if you shoot with a low or medium f-number. But when you shift to higher f-stops, the aperture increases so much that it captures even the tiniest dust speckles. This may not be visible instinctively, but after you load the image into a bigger screen, you will be able to see shadowy dots in the image.

In order to avoid this, pay careful attention to the dust in your lens. Clean your lens frequently when you’re outdoors or just use a larger aperture.

What Is the Wide Aperture Mode?

Often, people feel confused as a wide aperture mode is actually achieved with reduced aperture. It’s simply a commonly misused term.

A wide aperture is when the focus plane is very wide. All the foreground subjects are in focus while the background is blurred. This can be achieved by lowering the aperture.

This is basically a thick depth of field effect with the main subjects being in the foreground. The mode is typically present in compact cameras, point & shoot cameras and smartphones where the exposure settings cannot really be set manually.

Wide aperture mode is used to put high emphasis on the foreground and hide background elements. It could be done intentionally or simply because of distractions in the background.

However, if your exposure settings can be adjusted manually, you do not need to worry about this.

How Do I Make My Aperture Wider?

To widen the aperture is to place your subjects inside the focus plane, not behind or infront of it. So it’s not just the aperture you’re changing, but also how you’re placing your focal objects.

Reduce your aperture or select the wide aperture mode, and place your subjects horizontally within the focal plane.

Low Aperture

As discussed before, a low aperture is great for keeping the entire image in focus. Landscape photography, nature photography – all benefit from a wide aperture.

Remember, a low aperture means to increase the f-numbers. Just be careful of unwanted elements like diffractions, lens aberrations and dust particles.

Aperture Chart

This aperture chart will help you understand what is aperture in photography and summarize all the information discussed above.


Which Aperture is Best for Product Photography?

For Clothing product photography, a medium to large aperture works best. Refer to the chart above for approximate ranges.

Which Aperture is Best for Landscape Photography?

Medium to small aperture works best for landscape. However, ensure the environmental lighting is great and your lens is clean! Or else get ready for diffraction & dust!

Which Aperture is Best for Portrait Photography?

Undoubtedly, a large aperture. This puts complete focus on your subject(s). Just ensure that they are placed in the focus plane properly, and that they stand horizontally inside it.

Final Verdict

Take a bow! Now that you have learned everything there is to know about aperture, you can start your photography journey no matter where your skill level is now! Now, you never have to ask the question “What is aperture in photography?”. Happy photography!

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Lisa Rose


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Lisa Rose has been creating quality and satisfactory content for more than 7 years. Having appropriate insight into writing has helped her understand clients' requirements. At present, she is a dedicated cognizant writer and applying her skills to numerous people and their businesses to reach more people.

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