Aperture is one of the three elements that build up the exposure besides the shutter speed and the ISO. Understanding the aperture meaning makes getting to grips with taking an evenly exposed photo a lot easier.
As you develop your photography skills over time you will want to have more and more control over your camera. This means that you will leave behind the auto modes and start shooting more in manual or half-manual modes like aperture priority and shutter priority. Even though auto modes have their advantages, you can bring out the best of your photography by controlling all three settings of the exposure triangle manually.
Most photography experts say that in a lot of cases the aperture has the biggest impact on a photo. Using different apertures also opens up more creative avenues through unique effects. This article will teach you what they are and how to use them to your advantage.
Step 5 – What Is Aperture?
The easiest definition for aperture is to say that it’s the opening of your lens. This adjustable “hole” in your lens is also called the diaphragm. If you take a closer look at your camera’s lens, you should see something like this:
The best way to understand the aperture definition is to think of it as the pupil of an eye. In low light conditions, the pupil is wider letting in as much light as possible. When there’s too much light, like direct sunlight, it shrinks to compensate for the amount of light. In photography, the lens of your camera works just like this.
Following this analogy, would you use a wide or narrow, small aperture to photograph a darker scene like a beach after sunset?
You should already know the answer to this question, but if not I give you a little hint: If you enter any dark place, your pupil widens up. 🙂
As the diameter of the aperture size changes, it allows more or less light onto the sensor. This depends on the situation and the scene being photographed.
Put simply, when talking about light and exposure, a smaller aperture allows less and a larger aperture allows more light in.
How to Understand the Aperture Language
Aperture can be confusing sometimes. Some people will say a wide or narrow aperture, but others might say a large aperture number or a small one. What is the difference? A wide aperture refers to the wide opening in the lens, where an aperture like f/1.2 or f/1.8 is being discussed.
Don’t worry if you don’t understand what these f/numbers are yet, this will be tackled in the next section, just follow along.
A larger aperture number refers to the number of f/stop when f/22 or f/32 is being discussed. A large aperture number, a narrow or a small aperture are the same things, one talks about the size of the number and the other relates to the size of the opening in your lens.
How Is Aperture Measured and Changed?
In photography, the aperture size is measured using something called the f-stop scale. On your digital camera, you’ll see ‘f/’ followed by a number. This f-number denotes how wide or narrow the aperture is. The size of the aperture affects the exposure and depth of field (also tackled below) of the final image.
Getting Familiar With the F-Stop Scale
What may seem confusing is that the lower the number, the wider the aperture. This means that your camera aperture settings will be wide open at a smaller f stop number, like f/1.4 (usually this is the maximum aperture of a lens). At higher numbers, like f/16 or f/22, you’ll get a narrow, small aperture.
Why a low number for a high aperture? The answer is simple and mathematical, but first, you need to know the f stop scale.
The scale is as follows: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22.
The most important thing to know about these numbers is the following. As the numbers rise, the aperture of the lens decreases to half its size with every stop. Half meaning that it allows 50% less light through the lens.
So if take an f-stop like f/2.8 and change it to f/5.6 our image will have four times less light than at the starting aperture size of f/2.8. This is because we skipped a whole stop (f/4) and stepped two stops up. Remember, one stop means 50% less or more light depending on widening up or narrowing down your aperture.
This is because the numbers come from an equation used to work out the size of the aperture from the focal length. You’ll notice on modern-day cameras that there are aperture settings in-between those listed above.
These are called third or 1/3 stops, so between f/2.8 and f/4 for example, you’ll also see f/3.2 and f/3.5. These are just here to increase the control that you have over your settings.
Now things begin to get a little harder. If you get confused, skip to the next section as the most important part has been covered.
For example, say you have a 50mm lens with the aperture set to an f stop like f/2. To find out the width of the aperture, you need to divide the focal length (50mm) by the aperture (f/2), giving you a diameter of 25mm.
Then take the radius, multiply it by itself (radius squared) and multiply that by pi. The whole equation looks something like this: Area = r²*pi.
Here Are a Few Examples:
A 50mm lens at f/2: 50mm/2 = a lens opening 25mm wide. Half of this is 12.5mm and using the equation above (pi * 12.5mm²) we get an area of 490mm².
A 50mm lens at f/2.8: 50mm/2.8 = a lens opening 17.9mm wide. Half of this is 8.95mm and using the equation above (pi * 8.95mm²) we get an area of 251.6mm².
Now, it doesn’t take a genius to work out that half of 490 is less than 251. This is because the numbers used are rounded to the nearest decimal point. The area of f/2.8 will still be exactly half of f/2.
Changing Your Aperture
Now that you are aware of how the aperture is measured we can take look at how you can change it on your camera.
At this point, it’s important to mention that there are some cases when you will not have full control over your aperture regardless of the settings on your camera. This happens at some so-called variable aperture lenses.
Variable Aperture Lenses
Variable aperture lenses are usually cheaper zoom lenses. The reason they are called variable aperture lenses is that the smallest aperture changes with the focal length.
Most kit lenses just like the 18-55mm f/3.5-5.6 kit lens come with a variable aperture. This means that on smaller focal lengths like 18mm you can set the maximum aperture of f/3.5. As you zoom in with the lens and reach longer focal lengths the maximum aperture you can set will decrease.
Finally, if you reach the longest focal length of your variable aperture zoom lens, in this case, 55m, the widest aperture this lens can produce will be f/5.6.
This could be very hard to deal with as in low light conditions you really need those extra f-stops. When you’ll put this into practice you will see that even f/3.5 can be insufficient when you have less light to work with.
On the other hand, if the amount of light is not a problem and you would like to use a small aperture like f/11 or higher, you can always set your aperture to a higher f-number regardless of the focal length.
This is the reason most professional photographers tend to use prime lenses. Prime lenses are fixed focal length lenses (this means that you can’t zoom with them) that usually capable of very large aperture openings like f/1.4 or even f/1.2.
These small aperture numbers are very useful when you need to shoot in low light or if you want to achieve a shallow depth of field, which will be tackled later in this article.
These lenses are usually more expensive. There could also be a big price difference between two prime lenses with a difference of one single f stop. This is because there are a lot of cases where one single f-stop can make a really big difference.
Once you reach your lenses maximum aperture you’ll only have two options to compensate for a dark exposure. One is shutter speed and another is ISO.
Most of the time, you can’t just tweak these further especially if you don’t have much light. Bringing up the ISO will make your image very noisy, and slower shutter speeds can make it blurry.
Now, back to the topic of how to change the aperture in your camera.
On modern digital cameras, you may have noticed that there are certain modes, including full-auto, P, “Tv”, “Av” and so on.
Now in full-auto modes, you can’t adjust any of your exposure settings. Your camera sets the optimum aperture, ISO and shutter speed for you, always compensating for a “perfect” exposure.
All digital cameras (and some film cameras) have a built-in light meter, which measures the amount of light of your scene being photographed. This light meter helps your camera to determine the right settings of your exposure when you snap an image.
Before you’d think that auto modes are only useful for those who don’t know how to handle their camera yet, I can assure you that a lot of photography experts still use auto modes.
Just think of event photography. Things happen really fast around you and you need to react even faster! Now in situations like this, you can have a hard time dealing with continuously changing conditions.
Here’s an Example of it:
You are shooting a wedding and you are in the church where normally there’s less light than outside on the street. The couple turns around after the ceremony and starts walking out of the church. You are still shooting pictures of them but as you keep walking there will be more and more light coming in from the outside.
Now if it’s a bright sunny day, there will be a huge difference between your indoor and outdoor exposures. Instead of continuously adjusting your aperture, ISO, and shutter speed settings, selecting the auto mode(s) can really make a difference. Your camera will automatically set the correct aperture, ISO and shutter speed settings even though the amount of light is constantly changing. Pretty good, isn’t it?
Now as I said before the auto mode can be helpful, but it doesn’t put you in full control of your camera. Fortunately, it’s not black and white and there are modes in-between full-auto and manual.
“Tv” and “Av” Modes
If you are not satisfied with how your camera exposes in auto mode but still want flexibility, Av and Tv modes are for you! These modes give you the freedom to focus more on your surroundings while still keeping you in control. But how is this possible?
These two are called Aperture priority (Av) and Shutter (Tv) priority modes. Basically what they do is that you can control your priority setting depending on which mode you select and leave the rest to technology.
Aperture priority (Av mode)
In aperture priority mode you can set your aperture to a certain f-number, while your camera compensates with setting shutter speed and ISO automatically to maintain a perfect exposure. This mode is useful if the priority (as in the name of the mode) is your aperture.
To put this in an example, let’s say you are shooting a subject where you want to keep smaller apertures (high f stop numbers like f/16 or f22) to achieve a certain effect in your final image.
If you choose aperture priority mode and fix your f stop you won’t have to worry about any changing light conditions as you will get the same exposure every time you release the shutter button. Remember? You’re still in kind of a half-auto mode.
But! Keep in mind that if you’re shooting with such a small aperture the compensation in shutter speed might be very radical and your camera can even set the shutter speed close to a whole second or more.
This depends on how much light you have. All in all, aperture priority is a good choice when you have a lot of light, so you don’t have to worry about how your camera changes the shutter speed for you.
Aperture priority is usually used when you have a lot of light, for example, bright, daytime landscape photography.
Shutter Priority (Tv mode)
Shutter speed priority works just like the Av mode but instead of defining your base aperture you can fix your shutter speed. Now the ISO and aperture will be adjusted automatically. One good example of when to use Tv mode is sports events when there is a lot of movement.
The main focus when photographing an event like this is usually to capture the motion in your image. Now, this can be very difficult. Just think of a football game. Players constantly run, they move very fast and they change their direction all the time. In this case, you can choose the right shutter speed to freeze their action and let your camera do the rest for you.
This mode is pretty self-explanatory. In manual mode, you are in control of everything that affects your exposure. However, it takes a lot of practice and learning to really get used to the manual mode.
Before you would go out and start shooting only in manual mode, I recommend you try out the previous modes as well, to really see how they affect your image.
Step 3 – How Does Aperture Affect Exposure?
By now you should probably know the answer to this question but if not, let me refresh it for you.
The change in aperture size correlates with exposure. The larger the aperture size, the more exposed the photo will be and vice versa.
The best way to demonstrate this is by taking a series of photos and keeping everything constant with the exception of the aperture.
All the images in the slideshow below were taken at ISO 200, 1/400 of a second and without a flash. Only the aperture size changes throughout.
This set of photos was taken before the recent purchase of my large aperture capable f/1.4 lens, so the photos are in the following order: f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22.
A good way to see the changing size of the aperture is to look at the size of the out of focus white circle at the bottom left of the image. The main creative effect of aperture, however, isn’t exposure, but depth of field.
Step 2 – How Does Aperture Affect Depth of Field?
Aperture and Depth of Field
Now, the depth of field is a big topic in photography. Apart from causing a difference in exposure, adjusting your aperture affects the depth of field. This is where things get a little bit more interesting.
What is Depth of Field?
For now, I shall summarize it by saying that it is all about the distance at which the subject will stay in focus in front of and behind the main point of focus. To make it a little bit easier to understand, we can say that it’s the area of focus.
How Aperture Affects the Depth of Field
If you set a large aperture on your camera and take a picture, you will see that the area of focus will be very small. This is called a shallow depth of field. Actually it’s a little bit more complex than this because the focal length of your lens and your distance to your subject also make a difference in the depth of field and area of focus.
The opposite of shallow depth of field and wide aperture is a deeper depth of field. You can achieve this by setting smaller apertures like f/16 or so. Smaller apertures will produce a sharper image and a greater area of focus.
Before I show you a selection of photos taken at different apertures, take a look at the diagram below. If you don’t understand exactly how this works, don’t worry you will understand everything when you see the pictures below.
For now, it’s important for you to know the effects and understand how depth of field changes.
Here is an example of a photo taken at f/1.4. With the subject moving away from the lens, it’s easy to see the effect that the shallow depth of field has on the image.
As mentioned, here’s a selection of photos all taken on aperture priority mode. The exposure remains constant and the only changing variable is the aperture.
The photos in the gif below are in this order: f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22. See how the depth of field increases every time the aperture size is decreased.
You can get very creative with choosing different aperture settings for changing the depth of field.
Large aperture openings can have very interesting effects on the image. Most of the times they are used to create a soft and blurry background.
This is a nice way of separating your subject from the background. This technique can also create great depth and give a lot of mood and emotion to your image. Shallow depth of field helps the viewer to really focus on the subject but you should be careful with it.
At very small aperture numbers like f/1.2, your area of focus can be very narrow. This means that your subject can easily fall out of focus. Even though a nice shallow depth of field can be very pleasing to your eyes, but the first priority should always be your subject.
This is a common problem for a lot of people doing portrait photography.
I, personally like to shoot portraits with a 50mm or 85mm lens, using a wider aperture opening like f/1.8 or so. Now if my subject is really close to the lens I usually consider using a bit higher f-stop number like f/3.2 or even f/4 to ensure that my subject’s face is in focus and sharp.
Depth of field can be so shallow that basically your area of focus in only a few millimeters. So be careful with using a small aperture number as it can easily ruin your image.
Another creative photography effect of a large aperture is bokeh. Bokeh is basically the out-of-focus blurry background of your image. It’s the most effective when you have a very shallow depth of field and a rich background. You can see it on the below picture how the city lights create this effect in the background, behind the subject.
(subject + night bokeh by city lights in the background)
Smaller apertures like f/8 or f/16 are usually used to create a wider focus area. This is most commonly used in landscape photography.
Just think of a scene with a lake in the foreground and mountains in the background. Here you have a great distance between the lake and the mountains but you want to have as many things to be in focus as possible. To achieve this one, you have to set your aperture to a high f stop number.
Bigger f stop numbers can be useful at portraits as well to make sure all facial features are sharp and in focus in the image.
But remember, by dialing up the aperture, your image will be darker and you need to compensate for an evenly exposed image.
What Are the Uses of Different Apertures?
One thing to note is that there are no rules when it comes to choosing an aperture. It depends greatly on whether you are going for artistic effect or to accurately balance the light in a scene.
To best make these decisions, it helps to have a good knowledge of traditional uses for the different aperture listed below.
- f/1.4 – This one is great for low light situations. It also gives a shallow depth of field. Best used on a shallow subject or for bokeh effect.
- f/2 – This range has much the same uses, but an f/2 lens can be picked up for a third of the price of an f/1.4 lens.
- f/2.8 – Still good for low light situations, but allows for more definition in facial features due to a deeper depth of field. Good zoom lenses usually have this as their widest aperture.
- f/4 – Autofocus can be temperamental. This is a safe aperture setting you’d want to use for portrait photography for nice and more detailed portraits. You risk the face going out of focus with wider apertures.
- f/5.6 – Good for photos of one or two people but not very good in low light conditions though. Here, use a bounce flash if you have one.
- f/8 – This is good for large groups as it will ensure that everyone remains in focus.
- f/11 – More often than not, here is where your lens will be at its sharpest. Good starting aperture for landscape photography and also high-detailed portraits of your subject.
- f/16 – Shooting in the sun requires a small aperture, making this a good ‘go-to’ point for these conditions.
- f/22 – Best for landscape photography where you want noticeable detail on your subject and the background too.
As I said before, these are only guidelines. It’s only up to you how you use this knowledge in your photography. Now that you know exactly how the aperture setting will change a photo, you can experiment yourself and have fun with it!
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