Aperture is one of the basic foundations of photography. Together with ISO and shutter speed, it makes up the Exposure Triangle (Learn to manage The Exposure Triangle in Photography)
What elements are affected by a change in aperture?
Changing the aperture value (f) affects three key parameters: exposure (EV), depth of field, and sharpness, which all influence the final result of your photo.
Aperture is a fundamental camera setting, and this guide will help you understand what aperture is in photography and how it affects your images.
What is aperture in photography?
The aperture of the lens controls the amount of light that enters and hits the sensor. This can be adjusted using the diaphragm mechanism. When the diaphragm is fully open, the maximum amount of light enters, and when it’s more closed, less light enters.
For example, in low light conditions, such as when capturing the Milky Way, we use wide apertures to allow more light to enter and hit the sensor. During daylight photography, we use a smaller aperture to let in less light and take advantage of a greater depth of field.
What is F-stop number in aperture?
The maximum aperture of a lens is called the “maximum aperture” and is determined by dividing the focal length of the lens by the diameter of the aperture. The result is known as the f-number or f-stop (where f stands for focal length).
As the aperture size decreases, the f-stop number increases. This can be confusing, but it’s important to understand that each f-stop is a fraction, even though it’s not expressed with a numerator. Additionally, as the f-stop value increases, the amount of light entering is halved compared to the previous, larger aperture.
This may seem confusing, so let’s use an example to better understand how f-stop apertures work in photography: Imagine you’re letting water flow out of a 1-inch pipe. The pipe breaks, and you need to replace it with a 1/2-inch pipe. With the smaller pipe, it will take twice as long to let the same amount of water flow out. Instead of pipes, let’s talk about lenses, and we can say that you’ve switched from an f1 aperture to an f2 aperture. At f2, less light enters because the diaphragm inside the lens is more closed.
The F-stop number (or focal-stop number) refers to how open or closed the aperture is in your camera lens. In photography, the most common F-stop values follow a sequence like this: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22 .
How many times have you heard a photographer say, “I used the maximum aperture” or “I used a very small aperture”?
What is a wide aperture and a small aperture?
A large aperture is a wide opening in the lens that lets in more light. So when you use the maximum aperture, it means you’ve opened the diaphragm of your lens to its fullest, allowing the maximum amount of light to reach the sensor. This depends on the lens, but it is usually f1.2 or f1.4.
On the other hand, a small aperture is created by turning the dial in the opposite direction, resulting in a more closed diaphragm. In this case, less light enters and hits the camera sensor.
A small aperture typically ranges from f14 to f22. The maximum closure of the diaphragm depends on the lens, but it usually goes up to f22. Later, we’ll discuss the issues that arise when shooting with a very small aperture.
How aperture and exposure are related?
Aperture plays a key role in exposure value (EV). Together with ISO and shutter speed, they form the exposure triangle, determining the exposure (EV).
Let’s say the ISO and shutter speed are fixed. By changing the aperture, we will change the exposure. Decreasing the aperture (using a higher f-stop, like f16) reduces the amount of light entering, making the exposure darker (photo becomes darker). On the other hand, increasing the aperture (using a lower f-stop, like f4) allows more light to enter and hit the sensor, increasing the exposure value (photo becomes brighter, more exposed).
f16, 1/120 sec, ISO 100 < EV
f4, 1/120 sec, ISO 100 > EV
To maintain the same exposure EV, you will need to adjust the other two elements of the exposure triangle: shutter speed and ISO.
Aperture and depth of field in photography
In daytime landscape photography, it’s important to use the aperture to control depth of field. In most cases, you can set your camera to “A” mode (where you choose the aperture and the camera sets the shutter speed), while manually adjusting the ISO.
Only when the shutter speed makes a difference based on what you want to capture, should you switch to “M” mode. It’s not wrong to always work in “M” mode; in fact, it’s the best way to learn how to control exposure properly. However, in daytime photography, using “A” mode will speed up your workflow in the field.
How does aperture affect depth of field?
Depth of field (DOF) is one of the key elements you need to understand to master the basics of photography. It refers to the area of the image that is sharp and in focus.
The larger the aperture used (for example, f2.8), the shallower the depth of field you can capture. This means that a larger portion of the image will be blurred and out of focus.
On the other hand, the smaller the aperture (for example, f16), the greater the depth of field in the photo. This means that more areas of the photo will be sharp and in focus.
Smaller aperture (f16) = Large Depth of Field = shorter hyperfocal distance
Larger aperture (f2.8) = Shallow Depth of Field = longer hyperfocal distance
Let’s look at a practical example: if we’re facing a wide landscape, with flowers nearby and mountains in the background, and we want to create a strong photographic composition by getting closer to the flowers, the aperture plays a crucial role in the depth of field, which determines how much of the image will be in focus.
Imagine we want to achieve hyperfocal focus to get everything sharp from one meter to infinity with a single shot.
By setting a small aperture like f14 or f16, we’ll have a greater depth of field, allowing both the flowers near us and the distant mountains to be in focus.
On the other hand, if we use a large aperture, like f2.8, we’ll have much less depth of field, meaning only one of the two elements, or the flowers or the mountains will be sharp, depending on the focus point.
You can also read our article “What is Hyperfocal Distance in Photography?” to learn more about this important factor in landscape photography.
Aperture and sharpness in photography
In addition to exposure and depth of field, there is a third important aspect influenced by aperture, and that is sharpness.
What is the sharpest aperture?
There is no rule to determine the sharpest aperture for a lens, as it varies depending on the lens model. Typically, the sharpest aperture is found by closing the aperture by about 3 stops from the lens’s maximum aperture. So, if the maximum aperture of the lens is f2.8, the sharpest result is usually around f5.
Therefore, working with mid-range apertures will give you the best sharpness and image quality. Using the extreme apertures, both maximum and minimum, will result in less sharpness and lower image quality. For this reason, it’s recommended to avoid using these extremes in photography.
Diffraction in Landscape Photography
Using a very small aperture (f18/f20/f22) can cause diffraction, leading to a loss of sharpness in the image.
Diffraction is a physical phenomenon that affects how light waves travel when they pass through a small opening, such as a tiny gap. When light passes through a very small aperture (a very closed lens diaphragm), it creates a series of light waves that interfere with each other. This causes the light waves to spread out in a non-linear way, reaching the sensor and causing a loss of sharpness and image quality.
This is why we avoid using too small apertures, even though it may give us a greater depth of field.
What is Optical Vignetting in Photography?
Using too wide aperture (the maximum aperture the lens allows) can lead to optical vignetting.
Optical vignetting is a phenomenon that occurs when very wide apertures are used with non-prime or lower-quality lenses. Vignetting results in a decrease in brightness at the edges of an image compared to the center. This creates a dark halo around the edges and especially in the corners, leading to a loss of sharpness and image quality. Closing the aperture reduces this problem, which is especially noticeable with wide-angle lenses.
My advice is, when shooting in low light and you need a wide aperture to capture more light, try to close the aperture by at least one stop from the lens’s maximum aperture. Of course, using high-quality prime lenses significantly reduces the issue of optical vignetting.
What is the best aperture in photography?
One of the most common questions in photography is: What is the best aperture?
There is no single answer because the best aperture depends on what you want to photograph and the artistic result you want to achieve.
Here are some examples of commonly used apertures based on the type of photography:
Apertures in Landscape Photography
In landscape photography, narrower apertures are typically used to get more depth of field and more areas in focus in the scene (f8/f16).
Apertures in Night Photography
In night photography, wider apertures are typically used to capture as much light as possible in low-light conditions (f1.4/f2.8).
Remember that the choice of aperture in photography always depends on the type of scene you want to photograph and what you want to create, based on your artistic perspective.
If you’re photographing a wide landscape with a wide-angle lens, you probably want most of the image to be in focus, so you’ll work with the hyperfocal technique and use a small aperture (f14/f16).
If you’re photographing an animal or a person, your goal may be to have a blurred background to highlight the subject. To do this, work with a larger aperture (f2.8/f4).
Talking about your artistic perspective, you can play with the aperture to create the effects you like. For example, if in a wide landscape you prefer a blurred foreground with the main subject in sharp focus, you can open the aperture and focus on the distant subject.
You can also use high F-stop values, like f20 or f22, to create Sunstars (sunbursts) and Moonstars.
Tips on When to Use Aperture Mode (A) in Photography
For landscape photography, I recommend always using Aperture Mode (A), except when the choice of shutter speed becomes crucial for what you want to photograph. For example, if you want to achieve the motion effect of flowing water in a river, waves, or if you’re aiming for a long exposure, then you should switch to Manual Mode (M).
When shutter speed is not critical, using Aperture Mode (A) makes the workflow faster and easier. When you’re facing a landscape, the first thing you think about is how to focus, and here, the depth of field given by the aperture plays a key role. Also, with this shooting mode, you can quickly adjust the exposure by +5/-5 stops using the exposure compensation button.
For night photography, you should always use Manual Mode (M) and manually control all three parameters that make up the exposure triangle.
Conclusion
I hope this guide on mastering aperture in photography has clarified your doubts and that you’re now ready to practice and experiment with aperture settings in real-life shooting scenarios.
Keep in mind that using an aperture between f5.6 and f11 will give you the best quality in your photos. So, when the scene allows it, always try to use an intermediate aperture. However, there are situations where you’ll need to use more extreme apertures, such as low-light conditions in night photography where you need a larger aperture, or when you want a large depth of field in daytime landscape photography and use a smaller aperture.
Experiment by trying different apertures to see how the depth of field, image quality, the amount of light coming in, and the resulting exposure (EV) change.
Photography Tip: Keep an eye on the Histogram while shooting to make sure your image is correctly exposed.
