What is Aperture?

What is Aperture in photography?
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When talking about photography, what is aperture, and how does it affect the way our photo looks?

There are plenty of articles already which try and explain camera aperture in photography. The issue I have with most of them is that they’re unnecessarily complicated… not to mention very boring!

It’s like they’ve been written by professional photographers to impress other professional photographers…

If you’re learning about camera aperture, you’re obviously a beginner. You need to have the most simplified, uncomplicated explanation… and one that doesn’t put you to sleep!

Understanding aperture is absolutely essential to taking great photographs, so let’s get stuck in.

What is Aperture? A Beginner’s Guide

effect of aperture on light and focus by shotkit
The effect of aperture on light and focus – © Shotkit

Before I start, here’s a note for anyone who already knows a bit about Aperture in photography.

This is a beginner’s guide to aperture. As such, I’ve simplified it a lot. I’ve left things out that I don’t believe are essential at this stage, and I’ve written like I’m explaining things to someone learning photography for the first time.

I made the diagram above for you that should help you understand aperture. I’ll keep referring back to to it, so don’t worry too much about it right now.

1. Understanding Aperture | Let there be Light!

Smaller aperture example
This photo was shot at f/11 (i.e. a small aperture) to reduce the amount of light that was entering the lens.

According to the dictionary, ‘aperture’ means ‘an opening, hole, or gap.’

So if we think of aperture as an opening, it should be a little easier to understand.

There should be a setting on your camera (usually on a main dial at the top with all the little icons on it) showing a letter ‘A’, or ‘Av’.

This is the ‘Aperture Priority‘ mode, or using our new definition, ‘Opening Priority‘. So it governs how much of an opening you’re giving to your camera’s lens.

Side note: Aperture Priority is what I shoot in 99% of the time. I’ll tell you why later…

Do you want a big opening or a small opening? i.e. do you want a lot of light to be able to pass through the lens (via a big opening) or not much light (via a small opening)?

What happens when a lot of light comes through the lens? Your photo gets brighter. And if you make that opening smaller, guess what? Boom! Less light!

Aperture controls how bright your photo is.
Bigger aperture=brighter photo.
Smaller aperture=darker photo. EASY!

Using the aperture to control the amount of light that comes through your lens is sometimes a creative choice you make.

Other times you may be forced to choose a certain aperture based on the available light you have in your scene.

We’ll explore more on this in the understanding exposure lesson, but here’s a quick image to illustrate what I mean:

Understanding aperture and light
This image was shot at f/1.8 (i.e. a large aperture) since I needed as much light as possible to come through my camera’s lens (since it was a dark scene lit only by the small bulbs above).

OK, so here’s a question for you: How do you adjust your camera lens’ aperture (opening) to make it bigger or smaller?

We talk about aperture in photography using something called ‘f-numbers’ or ‘f-stops’.

Photographers may say, “what’s your aperture?”, or “what aperture are you shooting at”, but the reply would usually be the letter “f” followed by a number.

In photography school, you’d be expected to learn those numbers off by heart, but this really isn’t necessary.

I’ve been a pro photographer for 5 years now and still can’t recite them…

All you need to know is this:

The larger the f-number, the smaller the aperture.
The smaller the f-number, the larger the aperture.

Pretty confusing, right?! :-(

If I gave you the mathematical explanation about diaphragms and factors of light, this would be just like every other boring article on aperture out there, so just remember this instead:

When you see a number on your camera’s LCD which is preceded by a letter ‘f’, the closer that number is to zero, the lighter your photo should be.

The picture below should help explain this better. It shows how the larger the opening of your lens, the smaller the f-number is displayed:

fstops and aperture
The larger the aperture (‘opening’ in the lens), the smaller the numerical f-stop value.

Note that there are other f-stop numbers which aren’t shown in the diagram above. Your camera/lens may be able to shoot at f/1.8, or f/3.6 for example, but you can still easily visualize where these apertures would fall on the scale above.

As you’re a beginner photographer, I’m assuming you’re using a camera for a beginner with a ‘kit’ lens too. That lens is likely to have a maximum aperture of only f/5.6, or thereabouts.

You can see the maximum aperture written on the lens somewhere. It’s likely yours is a zoom lens, so it’ll have two maximum apertures written on it, like f/3.6-5.6.

If you’ve borrowed your mate’s fancy lens, there’s a chance the maximum aperture would be more like something a pro might use, like f/2.8, f/2, f/1.4… or even f/1.2!

(I’d recommend that you never give that lens back to your mate…!)

Why do pros need expensive lenses with larger apertures? One of the main reasons is to be able to take photos in low light, without having to use a flash on their cameras. If their lens has an aperture of f/1.4, it can ‘suck in’ lots more light than a lens with an f/4 aperture, for example.

Incidentally, lenses with a maximum aperture of f/2.8 or larger (i.e. f/2, f/1.4, f/1.2…) are known as being ‘fast‘. You may hear a pro talking about ‘fast glass’, which means lenses with large maximum apertures.

OK, so now you know the first thing to understanding aperture – it’s all about light.

Take a swig of coffee, as it’s time we talked about the second thing that aperture controls.

2. Understanding Aperture | What’s in Focus?

focus and aperture
Using aperture you can control what elements are in and out of focus in a photo to help tell a story. This image was shot at f/2.8 to direct the viewer’s eye to the wedding image on the TV, but leaving the grandpa out of focus (but still discernible), to suggest that he is somehow linked to the image.

Making your lens’ aperture (opening) larger or smaller lets in more or less light, but it also has another effect on your photo.

You’ve probably seen those cool pictures where some things are in focus (they look sharp), and other things are out of focus (blurry).

It used to be the case that only expensive camera lenses could create those effects, but that’s no longer the case. Damn you, iPhone!

The blurry part of a photo is sometimes called ‘bokeh’, which is Japanese for blur or haze. Photographers might say a certain lens has “great bokeh” or “creamy bokeh“.

If they start saying “bokehlicious“, unfriend them immediately!

Photographers also talk about what looks sharp vs what looks blurry in a photo using the term ‘depth of field’, or DOF.

Let’s simplify that term by calling it a ‘focused area’.

So when a photographer says a photo has a shallow or small focused area (shallow DOF), it means that there’s only a small amount of the photo which looks sharp as opposed to blurry.

If a photo has a deep or large focused area (large DOF), most if not all of the photo is in focus, and there’s little or no blur.

Understanding_Aperture_example_1
This photo was taken at f/2 (a large aperture), which is why the kids are sharp (in focus) but other elements are blurry (out of focus).

Why might you want sharp vs blurry areas? In a photo of a flower where you want to highlight it away from the other flowers behind it, maybe you’d prefer for the flower to be the only ‘focused area’ (shallow DOF).

On the other hand, you may want to highlight the whole beauty of that flower bed, and need everything to be the focused area (large DOF).

Understanding Aperture example 2
This photo was taken at f/16 (a small aperture), which is why all the rocks/branches are in focus, despite them being at different distances from the camera.

So how do we control the amount of focused area? Well there are actually a few factors that contribute to depth of field, but as we’re learning about camera aperture here, let’s concentrate on aperture first.

Here’s another confusing statement about aperture:

The larger the aperture, the smaller the depth of field.

Let’s break it down and rewrite that statement like this:

The bigger the opening in your lens, the smaller the in-focus area of your photo… and the greater the amount of out-of-focus (blurry) areas.

If you take a look at the image below, you should be able to visualise what I mean:

dof and aperture
As the aperture increases in size (i.e. the f-stop number becomes smaller), the amount that is in focus becomes smaller, while the out of focus elements (the bokeh) increase. With smaller apertures (f/5.6, f/8 etc), the opposite is true, with more of the image in focus and less blurred elements.

One other important factor that contributes to the amount of focused area (aka depth of field) is the distance you are from whatever you’re focusing on.

For example, if I’m taking a photo of a flower at f/1.4 (i.e. a large aperture) from 1 metre away, there should be lots of nice blurriness behind it, assuming that whatever is behind is a fair distance behind it (i.e. not perpendicular to it).

If, however, I’m taking a photo of that very same flower with identical camera settings, but now I’m standing 10 metres away from it… all that stuff behind it? No blurro. Check out the photo below to see what I mean:

aperture_and_distance-
The effect of the distance-to-subject on the depth of field (amount in focus). Both these photos were shot at an aperture of f/1.4 (i.e. a large aperture) – all I did was increase my distance from the toy truck in the second photo, which had the effect of bringing the background fence into focus too.

There may come a time where you want to control more precisely what’s in focus and what’s blurry in your image, and that’s where knowing more about how to calculate depth of field becomes important.

However, I don’t consider this important at this stage for a beginner learning about aperture. Besides, I have a really cool cheat to calculating this in seconds which I’ll share in a bit…

One Caveat about Lens Apertures

Controlling what’s in focus vs what’s out of focus (blurry) in your photo using aperture alone may not be easy with a beginner’s camera/lens setup.

Unless you can make your aperture larger than around f/4, (or get really close to your subject like in the toy truck image above), you may not be able to achieve that cool ‘bokeh’ blurred-background effect

In other words, unless you can turn the dial on your camera to make the ‘f’ number on the screen say something like f/2.8, f/2, f/1.8 or f/1.4, the amount that’s in sharp vs blurry won’t be very obvious.

As I mentioned before, you should find the maximum size of its aperture written somewhere on your lens. Usually there won’t be an ‘f’ in front of it, but rather a ‘1:’. In the images below, the lenses show maximum apertures of f/1.8 and f/2 respectively.

where to find aperture on lens
The maximum aperture is usually written on the lens as 1:XX (where XX is the widest ‘opening’ or aperture the lens can produce.)

It’s a bit of a broad generalization, but the cheaper the zoom lens, the smaller its maximum aperture. i.e. cheap zoom lens = not much cool blurry stuff in photo!

The ‘kit lens’ that comes with your camera will probably say something like ‘3.5-5.6’ on it, meaning that the maximum aperture varies between f/3.5 and 5.6, depending on how much you zoom it.

As you get more confident with your photography, you can start investing in better lenses that offer larger apertures, meaning more cool blurry stuff :-)

These lenses needn’t be expensive either – check out my guide to cheap camera gear for some affordable options, or take a look at these ones below:

3. Understanding Aperture | Light & Focus

directing viewer's eye using aperture
Using a larger aperture (f/1.8) allows you to direct the viewer’s eye to the sharp (in focus) elements of a photo, and away from the blurry (out of focus) elements. Leaving the out of focus elements in the image can help ‘tell the story’, without being the main focal point of the image.

Caffeine wearing off? Go grab yourself another coffee as it’s time to wrap this up!

Remember what I said at the start – this is a simplfied guide to understanding aperture. I’ve omitted some things that I don’t deem as important this stage. Trust me here :-)

So let’s sum up what we’ve learned so far. First, in fancy photographer talk:

A larger aperture in photography means more light and a shallower depth of field.

It’s best to get used to using that kind of jargon as it’s important when learning photography, but it’s ok to be secretly having an internal monologue with little ol’ Brain that goes something like this:

“ok ok so waitaminute…  that means if my lens has a bigger opening…  more light is gonna shine through that sucker… so my photo’s gonna be brighter! And if my opening is big, some weird science is going on to make more stuff in my photo go all blurry!” – Brain

When you adjust your aperture, two things change – light and focus.

You’ll see that with the other elements of exposure – shutter speed and ISO, when you adjust each one, two main things happen.

Aperture is linked with shutter speed and ISO, and eventually you’ll need to understand all three of them if you want to master your camera’s manual mode.

For now though, it’s enough to just understand aperture.

4. Understanding Aperture | Your turn!

Medium aperture example
This image was shot at f/5 (a medium aperture). The couple are in sharp focus, while the ring is also in focus (though not quite as sharp). If I had shot this image at f/1.4 (a large aperture), the ring would be too blurred and indiscernible (out of focus), making the overall image confusing.

As this is the Shotkit School and I’m your teacher, I feel like I should be giving you some homework!

Just like this guide to aperture, I’ll be keeping it super simple.

Step 1: Turn your camera’s main dial to Aperture Priority – ‘A’ or ‘Av’ mode.

Step 2: Turn your camera’s adjustment dial to change the aperture to the smallest number ( i.e. the largest aperture of your lens).

Step 3: Go outside when it’s light and take a photo of something from a metre or so away. If you’ve got a zoom lens, zoom it in completely, then don’t move it again. If your camera doesn’t focus, walk backwards until it does.

Step 4: Take a look at the photo. Make a note of what’s in focus and what’s blurry.

Step 5: Now turn that same adjustment dial to make that aperture number one click bigger. See the previous diagram as a reference for how the numbers change.

Step 6: Take another photo and repeat the process from step 4 until you’re well and truly bored!

Homework over! PARTY!!

Every camera, every lens, every camera+lens combination, and every other variable under the sun is out of my control here, so your results will vary a lot.

However, what you should have seen is that making changes to that ‘f’ number will govern how much of your photo is in focus as opposed to blurry.

If you’ve been paying attention, you should be cursing me at this point and shouting at your camera’s screen “why the hell isn’t my photo getting brighter or darker when I change this aperture thingy?! MARK LIED TO ME!!!”

Good question.

As you’re shooting in Aperture Priority, your camera is taking care of the exposure for you while you fiddle around with making stuff in focus vs blurry.

We’ll discuss the notion of ‘exposure’ later, but basically I’m referring to the ‘brightness’ of your photo.

So in Aperture Priority mode, your clever camera is calculating shutter speed and ISO on the fly to try and keep the brightness of your photos consistent, all the while you’re having a gay old time making stuff blurry.

Again, depending on many variables out of my control, you may well notice some variation in brightness of your photos even in Aperture Priority, but trust me – your camera’s doing its best to make sure that the only thing those ‘f’ numbers is adjusting is what’s in focus.

As I mentioned before, I shoot in Aperture Priority 99% of the time, and a lot of other professional wedding photographers do too. We all mastered Manual Mode, but then realised Aperture Priority is usually way more efficient.

We all want to tell a story using our photos by controlling what’s sharp and what’s blurry.

We want to direct the viewer’s eye away from the boring blurry stuff, and towards the interesting sharp stuff.

That’s how great aperture is. You can use it to start controlling what you want the viewer to see.

5. Understanding Aperture | Time Saving Tip

Aperture trick
Use this handy time-saving trick to learn aperture quickly and double check exactly how much is in focus.

Last week I discovered an awesome cheat to understanding aperture. It’s also a great way to check exactly how much of your photo will be sharp vs blurry, before you take it.

As I want to help as many other beginner photographers with this article as possible, I’ve hidden the tip  below – just click the button to share this post with your friends, and the tip will be revealed ;-)

For this tip you need a mirrorless camera with a ‘focus peaking’ function. Most mirrorless cameras have this, and it’s a really useful way to understand aperture, and what exactly will be in focus at any given ‘f’ number.

Step 1: Find the ‘focus peaking’ option in your mirrorless camera’s menu and turn it on.

Step 2: Switch your camera’s lens to Manual Focus. You may have to do this in the camera’s menu itself, under ‘Focus Modes’.messages

Step 3: Point your camera at an object with something in the background and start twisting your lens’ barrell to get it in focus. You should see a coloured line appear around the object to show it’s in focus – this is the ‘peaking’, and will differ in colour depending on your camera, but is usually red or yellow.

Step 4: Keeping everything else constant, start changing your lens’ aperture. You’ll see how the peaking lines start jumping around in the photo, showing you what else is falling into focus. Pretty cool, eh?!

I use this tip when photographing groups of people, who aren’t standing in a perfectly perpendicular line to me. I keep changing my aperture until the focus peaking lines are indicating all the peoples’ faces are in focus, but there’s still some background that’s blurry for the cool-effect :-)

Learn Photography with Shotkit

‘What is Aperture’ is the first in a series of lessons in the Shotkit School to help you learn digital photography.

Think of it as photography for dummies, explained in a short, concise, easily actionable format.

Each of the photography tutorials will be 100% free – just leave your email below to be notified when they’re released!

So how was your first lesson? Leave me a comment below to let me know if you found this tutorial on aperture easy to understand.

Mark Condon is a British wedding photographer based in Australia and the founder of Shotkit.

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  • Lovely simple explanations On a really important topic. I teach workshops to photographers and this post has helped me do it better. Keep up the great work Mark!

  • Enjoyed 1st lesson on Aperture, but annoyed at the end with not being able to learn the Time Saving Trip at the end. I do not subscribe/use social media in any of its forms.