Aperture: How To Get It — And Why You Should Care

Why does aperture have an important effect on your photography?

This is what you’ll learn in this article, as well as how it influences the look of your pictures. You’ll also find out how to adjust your camera settings to get the effect you’re looking to achieve.

Here’s an example of the different looks you’ll be able to achieve:

Aperture of f/3.2
Aperture of f/36

I remember feeling confused when I first tried to figure out how to expose my photos. It didn’t help that, with film, we didn’t have the instant feedback we get from digital nowadays. And I was too stubborn or proud to ask for help. 

I want to spare you that kind of frustration. This is why I wrote this second part of my mini-series on the exposure triangle! Its elements are aperture, shutter speed and ISO.

If you prefer listening rather than reading, here is the audio version of this article:

Ready to find out more? 

What is aperture?

 Let’s first discuss some physical basics. 

Imagine sand running through a funnel. The bigger the hole in the funnel, the more sand will drip through the funnel. The same thing happens with the concept of aperture, only with light. 

To avoid getting the perfectionists all upset, here’s the exact definition:

Aperture stands for the hole in the middle of your lens.  Overlapping blades form this opening which lets in the light into your camera. This hole can be made bigger or smaller to let in more or less light.

With most more advanced cameras, you can adjust the opening in the lens. 

How Do We Measure It?

The size of the aperture hole is expressed in f-stops.  A bigger hole lets in more light, while a smaller one lets in less light. 

The smaller the f-stop, the bigger the hole in the lens will be. And the larger the f-stop number, the smaller the aperture. 

These are the full aperture steps: f/1.4, f/2, f/2.8, f/5.6, f/8, f/11, f/16, f/22, f/32 and so on. If the other settings stay the same, an aperture of f/8 will double the exposure compared to f/11. 

What's The Effect Of Different F-Stops?

At f/2.8, the opening in the lens is very big. On the other hand, an aperture of f/16 describes a little hole. An aperture of f/1.4 doubles the exposure compared to an aperture of f/2.8. 

Going from one full stop to the next has the effect of doubling or halving the exposure. On a lot of cameras, you can also adjust the stops by ⅓ or ½ stops. 

Here is why a small f-stop number describes a large opening:

The following formula defines the physical size of the hole inside the lens: 

focal length/f-stop

Let’s say our lens has a focal length of 70 mm and compare the apertures f/2.8 and f/16 with each other. We will notice the following: Dividing 70 mm by 2.8 results in a physical diameter of 25 mm. 

On the other side, if we do the same for f/16, we realise that the hole will have a diameter of only 4.3 mm. This means that the larger f-stop number describes a smaller hole size. And the smaller number describes a bigger hole.

I know that this sounds a bit dry, especially if you’re a beginner. I felt like that as well, and it took me a while to learn about these things. I’m convinced that learning this early on will help you fast-track the learning process. 

Let’s move on.

How Aperture Affects Exposure

At constant shutter speed and ISO, changing the size of the aperture will darken or lighten your pictures. 

So, if you increase the f-stop number, your lens will let in less light. And this will result in a darker picture. Similarly, if you change to a smaller f-stop (=a larger hole), your photo will be brighter. 


The Exposure Triangle

You can adjust the exposure by changing the three components of the exposure triangle. This is because shutter speed, aperture and ISO influence each other. 

How and which of the three you will adjust will depend on the kind of visual result you are aiming for. As a result, you will be able to take pictures with more intent.

  • Let’s say you’re using a large f-stop number (=a little physical hole). If you want a well-exposed photo, you might have to raise your ISO to match the aperture. However, if you go too far, you might introduce ugly artefacts called noise. 
  • As an example, imagine that you’re taking a picture in a dark room. Because of the low light, you will have to choose a slow shutter speed. 
  • But what if you want to choose a faster shutter speed? If you’re not using a tripod, your only choice will be to either increase the or raise the ISO. As we mentioned before, high ISO can have a negative effect on image quality. 
  • And this is why, in low light, you will often end up selecting a bigger aperture than you would have done during the day. 

By the way, the concept of the exposure triangle is quite controversial. I neither like nor dislike it. I think it’s just a simplified way to say that shutter speed, aperture and ISO influence the picture-taking process a lot. I wouldn’t overthink it too much.

This article does a much better job than me explaining this concept in a very rational and logical way.

Let’s now  see what other effects aperture has on your photos.

How Aperture Affects Sharpness

The aperture you’re using in your photos has a direct effect on your photos’ sharpness. 

Sharpness describes your lens’s resolving power. You can understand this by first taking two photos. One at an f-stop of 2.8, and one at an f-stop of 10. Each photos should have lots of fine lines in them. 

Then you look at the photos on a screen and count how many lines you can see. Finally, you compare the numbers of lines in both pictures. The photo with the most visible lines identifies the aperture with a higher resolving power.

Using a very big or small aperture can soften your photos’ sharpness. In contrast, medium apertures tend to produce the sharpest photos. The softening of an image taken at a small opening is called diffraction.

But what if your aiming for the best possible image quality? 

In this case, you will need to know your lens’s optimal aperture. As a rule of thumb, take your lens’s largest aperture and lower it by three stops. Therefore, if your lens’s biggest aperture is 2.8, your camera’s optimal aperture will be around f/8. 

On the other hand, there will be times when you will be more interested in the visual effect the depth of field has on your pictures. And this can be achieved by using the appropriate aperture.

How Aperture Affects The Depth Of Field

Let’s see how aperture affects the depth of field. First of all, a wide aperture will tend to produce a shallow depth of field. A lot of photographers use this effect to isolate their subject from the front and background. 

Most noteworthy, this is used when taking pictures of people, making them the only sharp subjects in the picture. But you can use this effect for other applications too, like in macro photography. By isolating the subject through shallow depth of field, you attract the viewer’s eye to the main subject. 

Here is an example of a photo taken with a large aperture:

Taken at f/3.5

If, on the other side, if you choose a small aperture, your picture will tend to be sharp from front to back. This technique is popular with landscape photographers. They use it to keep all parts of their photo in focus. 

If you’re into physics, have a look at this explanation why a small aperture increases the depth of field.

Here is an example of a photo taken with a small aperture of f/16:

Sharp from front to back
Example of a picture which is sharp from front to back.

How Can You Adjust The Aperture?

Most DSLR, mirrorless and advanced point-and-shoot cameras let you adjust the aperture. I like to adjust aperture in manual or in aperture priority mode. 

In manual mode, you can adjust the aperture, the ISO as well as the shutter speed. When you change one setting, the camera will not try to balance out the other two. This is great if you like to have the highest possible control over your end result. 

On the other hand, sometimes you’ll prefer aperture priority mode. It’s great when you’re still learning. This is because it allows you to concentrate on framing, composition and other creative aspects. 

Furthermore, aperture priority is great if you’re trying to achieve shallow or wide depth of field. 

Let’s say that you’re taking a picture of a beautiful beach scene. If you want everything to be in focus, you set your aperture to f/16. Your camera will automatically the most appropriate shutter speed.

On the other side, with a small aperture, you have to keep an eye on the ISO and shutter speed settings. High ISO can lead to noise. Slow shutter speed might lead to blurry photos if you’re not using a tripod. 

How Are Aperture And Focal Length Related?

The focal length of your lens has a direct effect on the aperture size. The f-stop number describes how much light gets through the hole in the middle of your lens.

Wide-angle lenses let in more light than lenses with a longer focal length. This is because of the larger number of glass elements in telephoto lenses. 

At the same aperture, a 300 mm lens’s hole will be larger compared to the hole of a 24 mm lens. 

Furthermore, the same aperture will result in a wider depth of field on a wide angle compared to a telephoto lens. This is why portrait photographers prefer to use 80 mm lenses compared to 24 mm lenses. At constant aperture, the 80 mm lens will isolate the subject more than the 24 mm lens.

What About Zoom Lenses? 

Chances are that you own a zoom lens. They are practical, especially when you need to reduce the weight you carry on your hikes. 

You might have wondered why your aperture changed when you zoomed into a scene. If you look at your zoom lens’s specifications, you will see that it doesn’t only state a zoom range, but also an f-stop range. 

So let’s take the example of a 28-80mm 3.5-5.6 lens. At 28mm, it will not be able to open wider than an aperture of f/3.5. At 80mm, it will be limited to f/5.6.

Let’s now see how you can use aperture in creative ways.

How Can We Use This Creatively?

Remember that the way your photos should look depends on your creative vision.

Shallower depth of field
Deeper depth of field

Use A Big Opening

  • As already discussed, a big aperture allows you to separate your main subject from the background.  The out-of-focus area is called the bokeh effect. A lot of photographers love the bokeh effect. They describe it as more or less creamy depending on the kind of lens they are using. 
  • Also, you can use artefacts to create unique visual effects. One example is lens flare. This effect happens when light rays are being bent around the aperture blades. You will often see this happen with lenses which have less aperture blades.
  • It’s not always possible to know in advance which level of blurriness will result in the most pleasing look. Try varying the aperture size as well as the distance to your subject. This way, you will increase or decrease the background’s blurriness.
  • Move around and play with your camera’s settings. You can create attractive bokeh spots by shooting towards light sources. This is often used in street photography after sunset, or to produce a sun star effect during the day.
  • To get this effect, choose a wide aperture.  Using a wide aperture and a wide-angle lens, bright sources of light will look like a star in your photos. 

Be very careful when trying to get this effect with the sun. Pointing your lens into the sun could result in irreversible damage to your eyes! You should never look through the viewfinder when including the sun in your frame.

Use A Small Opening

  • Another creative use of aperture is to select a small aperture. This will allow to use a slow shutter speed and/or front-to-back sharpness in your images. 
  • This is often used by landscape photographers. This is because they like to interpret moving water as smooth and dreamy flows of liquid. 
  • You can use the same effect by taking photos of moving cars in urban environments.  The car lights will leave colourful light trails in your pictures.

How Aperture Works In Mobile Phone Cameras

With current smartphone cameras, you cannot adjust the aperture. This is a disadvantage when it comes to creative mobile phone photography. Phones tend to be fitted with very small sensors. They also come with wide angle lenses. 

This means that, even if you could adjust the aperture, it wouldn’t make a big difference. Phone lenses tend to have wide apertures. This increases their ability to take pictures in low light. 

Small sensors and wide lenses make it difficult to create shallow depth of field. To get this effect, you would need to get very close to your subject. 

But the small sensor and wide lenses help if you want to create pictures which are sharp from front to back. This is why a lot of people like to take pictures of landscapes with their mobile phones. 

Depending on your objectives, the fixed aperture of mobile phones might not represent a big issue. Nowadays, phones imitate shallow depth-of-field through the use of algorithms and artificial intelligence. The results can be good or bad, depending on your subjective taste. 

My wife took the following picture with my Huawei Mate 10 Pro smartphone. If you select the Portrait picture taking mode, it will try to identify faces in the frame. Once it has identified one, artificial intelligence will imitate the bokeh effect.

Thomas Burkl
Taken with a smartphone's portrait mode

My opinion is that, while smartphones have come a long way, they are still no match compared to a real camera. You may be able to take pictures which look impressive on your phone’s small screen. But printing them at larger sizes will reveal the heavy compression used by the software.


I hope this article has given you some insight into the intricacies of aperture. 

You will see that setting a strong foundation will benefit your pictures. Your future self will be thanking you. Now you have a better understanding of the basics of photography. 

Thank you very much for reading this article. If you would like to receive more photography tips, please subscribe below!

Thomas 😄

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