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DSLR Basics: Introduction to Aperture in digital photography, Depth of Field, & its types

Shubham Davey 0
Reading Time: 12 minutes

In this series of DSLR basics, it’s time to learn about aperture. Considering the confusing nature of this pillar element of digital photography, it’s important to understand it from basic to take better photos. Aperture, along with ISO settings, Shutter Speed, is one of the key elements of the Exposure Triangle. Taking things under control is not easy, as it seems. Aperture has a dedicated mode in your DSLR which lets you control the aperture and your DSLR takes care of the rest.

If you can get hold of aperture, you pretty much control everything. Aperture is something that sees the scene you are about to shoot, nothing else in the DSLR is even close to what role the aperture plays. If the DSLR is the theater, the aperture is the lead role there.

In this post, I will be touching a lot of points that will help you understand the concept rather than the theory. Since it’s for beginners, I will try to go as easy as possible. As part of this guide on aperture for beginners, I will cover the following:

  1. What is Aperture? How does it work? Why is it important in photography?
  2. How does the aperture affect the photos
  3. What is Depth of Field? What are its types?
  4. Aperture priority mode vs Manual Mode
  5. Best aperture settings
  6. Frequently asked questions(FAQs)

Without taking any further time, let’s begin 😉

#1 What is Aperture? How does it work?

Before I get into the nerd-mode, let me give a real-life example, to begin with.

Close one eye & take any subject(a pen, spoon or anything you can handheld), hold it as close to your eyes as you can see it crystal clear. Notice the background of that subject. Is it blur?

Now keep the eye closed & take that subject to one arm distance from your eyes. Notice the background of that subject. Is it blur?

Before I answer the questions above, I want to tell you that you’re halfway through understanding the concept. A good start is half done 👏

Okay, so in the first case, you had the subject too close to your eye. Close enough to see it clearly. You must have noticed a blurred background. Now depending on your eyesight power, the intensity of the blur would vary. I wear spectaclesđŸ€“, so the intensity was partially affected. Furthermore, the intensity of this blur depends on the distance between the subject and the lens.

All in all, when you had the subject close to your eyes, the background went blur.

aperture example The Lensed
Small(narrow) Aperture example. Shot by © Shubham Davey

In the second case, you pushed the subject to one arm distance. Unlike the previous scenario, the background did not blur, it was clear. Again, depending on your eyesight power and distance, the background clarity would vary. Farther you have the subject, clearer the background is.

For a change, look around you. Look at a subject a few yards away, notice the background without shifting your focus from the subject. The background gets clearer and clearer.

Large(wide) Aperture example. Shot by © Shubham Davey


Fascinating right? This is all about aperture.

If I’ve got your attention, read on. I have a lot more to share.

#2 Why is Aperture important in digital photography?

I’d not say important, I’d say most important element in digital photography is this. You can count this element as the eye of your DSLR.

So, in the above example, when you held the subject too close to your eye, the aperture of your eye went larger/wider to bring the subject into focus. This particular thing led to blurring out everything in the background, irrespective of the light intensity. Obviously, too much of light(like the sun in the background) would end being a pain in your eye.

On the other hand, in the second case, when you had the subject at the one arm distance. The aperture of your eye went smaller/narrow bringing almost everything in focus. The barrier of foreground and background is no more visible when your eye’s aperture is narrow.

Taking this concept to digital photography, the aperture of the lens in your DSLR also does the exact same thing. When you’re shooting in aperture priority mode, you are free to choose the aperture leaving the rest to the DSLR. By changing the aperture stops(I’ll explain stops in FAQ section) you can do exact same thing what your eye did. If possible, make someone do the above-mentioned activity and you notice their pupil. It will go wide when the subject is close and narrow when the subject is at a distance.

This wide open aperture is very important to focus on the detail you want in the frame and blur out the rest. This is why it’s the most important element in your DSLR. Imagine if your eye had everything in focus and not specific beautiful things when needed the most? The world would seem so pale and blunt.

I’ve been telling, aperture gets smaller, wider. But what exactly is this thing? In simpler words, the aperture is the size of the opening in the lens, just like your pupil. Narrower the pupil is open, more things come into focus. Wider the pupil opens, lesser the things are in focus. So, Aperture is nothing but the opening of the lens, that’s it and is measured in f stops. f1.4, f2, f2.8 etc. See the chart below for better visualization:

aperture size and Depth of Field

Now, what makes that blur effect? What is it called? It’s called Depth of Field. But,

#3 What is Depth of Field?

Depth of field is nothing but the portion of the image in focus.

Taking that example again, where you had just one thing in focus and everything else your eye could see was blurred out. In that case, the aperture of your pupil was wide(small f-stop number) bringing one object into focus.

On the other hand, in the second case, the pupil went narrower bringing everything in focus. These two different focusing outcome gives two types of Depth of Field.

  1. Shallow Depth of Field
  2. Deep Depth of Field

The first scenario is an example of Shallow Depth of Field, whereas the second one is the example of a Deep depth of field. Recheck the two example images above for better visualization.

Shallow depth of field is when a very small portion of the frame is in focus because the aperture is wide open. This wide aperture does not allow light from any object other than the one in focus, to enter the lens.

On the other hand, Deep depth of field has deep focus outcome. It has more portion of the frame in focus because the aperture is narrower. This allows more light from multiple subjects to enter the lens hence having a larger portion in focus.

Basically, narrower aperture(large f-stop number) lets the lens to see the distant objects and focus if needed. Inversely, the wider aperture(small f-stop number) doesn’t allow the lens to see anything else other than the subject it is focusing on, hence everything else blurs out.

Aperture has a huge impact on depth of field. Large/wider(large f-stop number) ones give shallow (decreased) depth of field and Small/narrower(small f-stop numbers) ones give deep (large) depth of field. Remember, depth of field is the portion of the image in focus.

  • Large Depth of Field is a large portion of the image in focus(large f-stop number)
  • Small Depth of Field is a small portion of the image in focus(small f-stop number)

Remember it like this, smaller the f-stop, smaller the portion of the image will be in focus.

It might be little confusing right now, but as you get along with your DSLR and experiment it, you’ll find it easier and useful.

#4 Aperture mode vs Manual  Mode: Which is the best? 

You can control aperture in two camera modes:

  1. Aperture priority mode
  2. Manual Mode

In aperture priority mode, you just have to control the aperture rest will be taken care your DSLR. In manual mode, you control the aperture, the shutter speed, compose the image, control the exposure and lot of such stuff.

Many professional photographers prefer to shoot in manual mode, where they control most of the elements. Furthermore, there are photographers who find aperture priority mode the king of all.

Reason being the ease of control. As I said earlier, that aperture is the most important element of a DSLR. And focusing only on this mode takes a lot of burdens away from you.

However, this becomes the question of priority. If you want to focus only on one thing, then the aperture priority mode will come handy. If you want to take complete control then none other than manual mode is the option.

#5 What are the best-recommended aperture settings

It’s totally dynamic, there’s nothing like best settings for aperture. It depends on what you are shooting, how much of the image you want to have in focus, the distance between the lens and the object and a lot of such factors.

For example, if you are shooting a landscape you probably wouldn’t want to miss even an inch of that view out of focus. In that case, you should go up in f-stops narrowing down the aperture. Depending on the focal length, and the distance between the lens and the subject, the area of the landscape will come in the frame. If you want to cover a wider area from near, you should opt for a wide-angle lens.

And if you are shooting something subjective and want to highlight it, go down in f-stops and widening the aperture. This will highly focus on the subject you are pointing. Furthermore, a lot of photographers get confused between focus and aperture. No doubt, smaller aperture focuses on one object(or nearer object) but this creates a shallow Depth of Field. On the other hand, the focus is just pointing your lens at a particular object. Nothing more than that, no depth of field stuff in this case.

Though both the features, bring the focus to a subject both the things are different. The focusing system depends on Aperture and not vice versa.

Frequently Asked Questions(FAQs)

As I have served a lot of information here, you surely have a lot of doubts. Furthermore, I have upfront tried to answer most asked questions that beginners have in this space.

How to change aperture in your DSLR?

You can control aperture in two camera modes:

  1. Aperture priority mode
  2. Manual Mode

In aperture priority mode, you just have to control the aperture rest will be taken care your DSLR. In manual mode, you control the aperture, the shutter speed, compose the image, control the exposure and lot of such stuff.

To change aperture in your DSLR, follow the following steps:

  • Change your camera mode to “Manual Mode“.
  • Manually set your aperture to the number enough to take better photos. 
  • Then set your shutter speed according to the aperture. Remember, shutter speed should inverse of the aperture. If you go one stop up in aperture, go one stop down in shutter speed. To keep the balance of the light exposure.
  • Keep your ISO as low as possible. Depending on lighting conditions, you can range from ISO 100 to 400.

Will a 50mm F1.2 lens take in more light at F1.8 than a 50mm F1.8 lens at that aperture?

Aperture is the amount of light passing through the lens, in terms of the size of the opening in the lens. If a 50mm f1.2 lens is set to f1.8, it will process exact same light as it does in a 50mm f1.8 lens  

Reason being, when the lenses at f1.8 let the exact same amount of light in. Unless you change the focal length(zoom it) the light allowed inside will remain same. Take a look at the chart below, it might come handy soon.

The aperture scale

What are the best prime lenses for best aperture’s settings?

A 50mm f1.8 is considered the best lens for taking almost any type of photograph. Be it landscape, portrait, macro, low light, you name it. It’s a multi-purpose lens, it’s just that the lens is a prime lens and you cannot zoom in. If you want to zoom in and take pictures of subjects far away, you can opt for f2.8 lenses. Some of the top performers in the list is:

Final thoughts

No doubts on aperture’s cruciality, it is single most important settings you should master. That’s why the depth of field and exposure depend a lot.

Knowing what the various apertures can do makes you the driver of your DSLR. It depends on the scene you’re working on that you’ve to up of down the f-stop. I’ve recently switched from manual to aperture priority mode for certain shots. Though experimental, but the results are fascinating.

Over to you. What do you think of the most important setting in your DSLR? Do you have any trouble in using it? Any specific doubt? Let me know in the comment section below.

Do you know someone who finds it hard to learn & understand this concept? Share this with them to teach them a real good thing.

Hope you liked this article. I’m sure you found it informative, if yes, then please share it in your social network. Furthermore, join my mailing list to never miss an update. I share blog updates and exclusive content in the mail.

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