Aperture
Written by: Nate Torres
Last updated: July 30, 2024
I get it, aperture is confusing. Especially if you are a beginner. You have acronyms like f-stop, and they're written like f/1.8, f/8, f/16...
"I thought this was photography, not math!"
But here's the deal: If you want to take your photography to the next level, you need to understand aperture, and that's what we're going to be covering today!
What is aperture?
Aperture in photography refers to the opening in the camera lens that controls the amount of light that enters the camera. Aperture is measured in f-stops such as f/1.8, f/4, f/8, and so on.
The lower the f-stop number, such as f/1.8, then the wider the aperture, allowing more light to pass through. The higher the f-stop number, such as f/8, then the narrower the aperture, allowing less light to pass through.
Take note!
You will hear photographers use slang such as "shooting wide open," which means they're photographing at a low f-stop number, which "widens" the aperture.
Aperture is like the pupil of your eye. Just like how your pupil dilates or constricts to control the amount of light that enters your eye, the camera's aperture controls the amount of light that enters the lens. By manipulating the aperture, you can influence the exposure, depth of field, and creative effects in your images.
Here’s the bottom line: By learning and mastering aperture, you can have greater control over the amount of light that reaches your camera’s sensor and the sharpness of your subject against the background.
As I’ll touch on later, this allows for greater creative control and freedom over your image composition.
In order to understand aperture, you must also understand what an f-stop is.
What is an f-stop?
In photography, an f-stop is a numerical value that is used to represent the size of the aperture opening in your camera lens. The f-stop number is also sometimes referred to as the "focal ratio" or "f-number."
The f-stop number is denoted by a series of numbers such as f/1.8, f/2.8, f/4, f/8, f/16, etc.
The f-stop scale is counterintuitive. The smaller the f-stop number, such as f/1.8, then the larger the aperture opening. The bigger the f-stop number, such as f/16, then the narrower the aperture opening.
You may think this is a bit confusing in the beginning like I did when I first learned about aperture. You have to remember that f-stop values are actually just fractions calculated by dividing the focal length of the lens by the diameter of the aperture.
Therefore, a smaller denominator (ex. f/1.8) indicates a larger aperture opening, while a larger denominator (ex. f/8) indicates a smaller aperture opening.
Take note!
When referring to aperture in photography, we speak in terms of f-stops.
Lower f-stop values allow you to create a shallower depth of field and a "bokeh" effect while higher f-stop values allow you to capture more of the scene in focus.
You might be thinking: "Every focal length of a lens is different."
This is true. If f-stop values are actually just fractions calculated by dividing the focal length of the lens by the diameter of the aperture. Then this means different lenses have different f-stop values.
Different lenses have different f-stop values
Different lenses may have different maximum and minimum f-stop values based on the type of lens that it is.
When referring to lenses, photographers will use the terms "maximum aperture" and "minimum aperture."
The maximum aperture of a lens, also known as the "fastest" aperture of that lens refers to the widest opening of the lens, allowing the most light to enter the camera. The minimum aperture, also known as the "slowest" aperture of that lens, refers to the narrowest opening of the lens, allowing the least amount of light to pass through.
For example:
Prime lenses, such as a 50mm prime lens, have a fixed focal length, allowing for wider maximum aperture values such as f/1.8 or wider. Zoom lenses, which have variable focal lengths, may have narrower maximum aperture values, such as f/3.5 or higher.
The difference in aperture values between prime lenses and zoom lenses is primarily influenced by the focal length and optical design of the lenses.
Just remember: Prime lenses typically have wider maximum aperture values due to their simpler design, and zoom lenses have narrower maximum aperture values due to their more complex optical design.
However, it's important to note that advances in lens technology have led to the development of zoom lenses with wider maximum aperture values, known as "fast zoom lenses." These types of lenses offer similar low-light performance and depth-of-field effects as prime lenses.
These fast zoom lenses are often more expensive and heavier than standard zoom lenses, but they provide greater flexibility in focal length while still maintaining a wide aperture.
Aperture and the exposure triangle
In order to truly understand aperture, a photographer must also know the other elements of the exposure triangle. Aperture is one of the three fundamental elements of the exposure triangle alongside shutter speed and ISO.
The exposure triangle represents the three key factors that determine the exposure in your image. All three factors - aperture, shutter speed, and ISO, work in unison to "balance" out the exposure in the image.
Because aperture is one of three elements that affect exposure, it's important to know how the other two elements (shutter speed and ISO) work in unison with aperture. The specific aperture, ISO, and shutter speed values will vary depending on the lighting conditions, subject, and desired creative effects.
While this is true, let's look at some common photographing scenarios so you can understand the relationship between aperture, shutter speed, and ISO.
Low-light conditions
When photographing in low-light conditions, such as indoors or during nighttime, you will need more light to hit the camera sensor so you can have a well-exposed image. In this case, you will need a wider aperture such as f/1.8 to allow more light in. You will also need a higher ISO such as ISO 1600 or higher, and a slower shutter speed.
Bright daylight
In bright daylight conditions, you may need to use a narrower aperture (larger f-stop value) to limit the amount of light entering the camera and prevent overexposure such as f/11 or higher. Due to the availability of light, you can also use a lower ISO such as ISO 100. A faster shutter speed such as 1/500 second or faster may also be needed in order to prevent overexposure.
Portrait photography
When shooting portrait photography, you may want to adjust your camera settings for a wider aperture (smaller f-stop value) to create a shallow depth of field and blur the background, drawing attention to the subject - such as f/2.8 or wider. You will also want to use a moderate ISO such as ISO 200-1600 to avoid noise, and a shutter speed that is appropriate for the situation and subject movement.
Landscape photography
In landscape photography, you may want to use a narrower aperture such as f/8, f/11, or higher in order to achieve a deep depth of field which will allow you to capture everything in the scene in focus. You will also want to use a low or moderate ISO based on lighting conditions and a shutter speed that is appropriate for the scene.
Action photography
When capturing fast-moving subjects such as sports or wildlife photography, you will need to use a fast shutter speed such as 1/500 second or faster to freeze the action. Because of this, you will most likely need to use a wider aperture such as f/2.8 or wider, and an ISO that allows for these faster shutter speeds without excessive noise.
Importance of aperture in photography
Now that we've covered the fundamentals of aperture in photography, let's take a look at all the reasons why aperture is important in photography.
Control over your exposure
As mentioned, aperture is one of the three factors that determine the exposure of an image, along with shutter speed and ISO. By adjusting your aperture, you can control the amount of light that enters your camera, affecting the overall brightness of your image.
A wider aperture (smaller f-stop number) will allow more light to enter resulting in brighter images. A more narrow aperture (larger f-stop number) will allow less light to enter resulting in darker images.
Understanding the aperture will give you precise control over how you choose to expose your images.
Depth of field control
Aperture also affects the depth of field in an image, which refers to the area of the image that is in sharp focus.
With a wider aperture (smaller f-stop number), you will create a shallow depth of field where the subject will be in sharp focus while the background is blurred. This is great for adding emphasis to your subject and creating a pleasing separation between the subject and the background. This is also how you create that bokeh effect.
With a narrower aperture (larger f-stop number), you will create a deep depth of field where both the subject and the background will be in sharp focus. This type of depth of field is great for landscape photography or street photography when you want the sharpness to be in the entire image.
Creative effects
Aperture also contributes to the creative effects and aesthetic appeal of a photograph. By intentionally selecting a shallow depth of field, you can introduce bokeh or starbursts into your image.
These creative effects can add further visual interest to your image and allow you to add your own artistic style to the image. I'll be covering more creative uses of aperture later in this guide.
Lens characteristics
Lastly, different lenses have different aperture capabilities, commonly referred to as the maximum aperture or "fastness" of the lens.
Prime lenses, which have a fixed focal length, often have wider maximum apertures (e.g., f/1.4 or f/1.8), allowing for better low-light performance and greater control over the depth of field.
Zoom lenses, which have a variable focal length, may have narrower maximum apertures (e.g., f/3.5 or higher), limiting the ability to achieve a shallow depth of field or shoot in low-light conditions.
When choosing a new lens, understanding the aperture capabilities of your lenses helps you make informed decisions when choosing lenses for your photography situations.
Common aperture/f-stop values
Before diving into knowing what aperture to use, let's take a look at the common aperture/f-stop values.
f/1.4 - f/2.8
The f-stop values of f/1.4 - f/2.8 are considered wide apertures and are most commonly found in prime lenses. By setting your camera to these f-stop numbers, you will allow a significant amount of light to enter the lens.
If you find yourself in low-light situations or if you want to create a shallow depth of field for blurred backgrounds and subject isolation, then these f-stop values are ideal. This aperture range is often used in portrait, street, headshot, and product photography in order to achieve a creamy bokeh and emphasize the subject.
f/4 - f/8
The f-stop values of f/4 - f/8 are considered mid-range apertures and are commonly used in various photography genres such as landscape, architecture, street, and product photography. These f-stop numbers provide a balance between depth of field control and overall sharpness. This allows you to have a wider area of the image in focus while still offering some creative control over background blur.
f/11 - f/22
The f-stop values of f/11 - f/22 are considered narrow apertures and are commonly used in situations where you need a deep depth of field such as landscape photography. These f-stop numbers allow for a larger area of the image to be in sharp focus, resulting in a greater depth of field.
There is a caveat: With these f-stop values, it may require a longer shutter speed or higher ISO setting to compensate for the reduced amount of light entering the lens.
How to know what aperture to use?
Now that we know the common aperture/f-stop values, let's take a look at how to know what aperture to use based on your given scenario.
Desired depth of field
The first point to take into consideration is to think about your desired depth of field.
As mentioned: Aperture directly affects the depth of field, which is the portion of the image that appears in sharp focus.
A wider aperture such as f/1.8 will result in a shallower depth of field creating a blurred background which is great if you need to emphasize your subject like with portraits, products, or headshots.
A narrower aperture such as f/16 will result in a narrower depth of field allowing for everything in the setting to be in focus which is great if you need to shoot landscape photography or group photos.
Subject and background
The second point to take into consideration when knowing what aperture to use is to think about your subject and background.
How to think about it: If you have a single subject that you want to emphasize, then you may want to opt for a wider aperture. If you have multiple subjects or focal points you want to emphasize, then you may opt for a narrower aperture.
Lighting conditions
The third point to take into consideration when knowing what aperture to use is to assess your current lighting conditions. Knowing how to use balance all three elements of the exposure triangle (aperture, shutter speed, ISO) is crucial during this step.
The available light in your shooting environment plays a vital role in determining the appropriate aperture to use. In low-light situations, you will most likely need to use a wider aperture to allow more light in. For brighter conditions, you can use both a wider and narrower aperture but you'll also have to tweak your ISO and shutter speed settings to ensure you don't end up with an overexposed image.
Lens characteristics
The fourth point to take into consideration is the characteristics of your lenses. Depending on what lens you are using, you will need to know your maximum aperture value or the "fastness" of your lens.
For example:
Let's say you have a zoom lens that reaches an f-stop value of f/3.5. If so, then that may not be the best lens choice if you want to capture a portrait photograph with that creamy bokeh background look.
Shooting mode
The fifth point to take into consideration is the shooting mode that you are currently using on your camera.
In manual mode, then you have full control over the aperture setting, and is the best mode to control all three elements of the exposure triangle. If you still don't know the ins and outs of manual mode, then you can also use aperture priority mode which will allow you to set the desired aperture.
In aperture priority mode, the camera will automatically adjust the shutter speed for proper exposure. In program mode or auto mode, the camera will select the aperture for you based on the scene and lighting conditions and these modes will give you the least amount of control.
Creative use of aperture in photography
Now that we know how to choose the correct aperture based on different scenarios, let's dive into some creative uses of aperture in photography.
Bokeh
The first and most popular creative use case of aperture control in photography is with bokeh. A wide aperture (e.g., f/1.8) can create a shallow depth of field, resulting in a blurred background while keeping the subject sharp in focus. This effect, known as bokeh, can add a dreamy or romantic quality to portraits, create a sense of separation between the subject and the background, and draw attention to the main subject.
Selective focus
The second creative use case of aperture control is with selective focus. By using a wider aperture, you can selectively focus on a specific part of your subject while blurring the rest. This technique is great for isolating a specific detail, such as a person's eyes or a flower petal, and creating a focal point that stands out in the image.
Sunbursts and starbursts
The third creative use case of aperture control is with the introduction of sunbursts and starbursts. Using a narrow aperture such as f/16 - f/22 and positioning the sun or bright light source in the frame can create a sunburst or starburst in your image.
What causes this? This is due to what's called diffraction.
It occurs when light waves pass through a small opening, such as the aperture of your camera lens, and bend or spread out. This bending or spreading of light waves causes them to interfere with each other, resulting in the formation of patterns or bursts of light.
At narrow apertures, the small size of the aperture creates a high degree of diffraction. This causes the light waves to spread out and create the characteristic rays or spikes that are commonly associated with sunbursts and starbursts.
Silhouettes
The fourth creative use case of aperture control is with silhouettes. By intentionally underexposing a subject against a bright background and using a wide aperture, you can create silhouettes that emphasize the shape and outline of your subject. This is a creative way to add a sense of mystery and drama to your image.
Light painting
The fifth creative use case of aperture in photography is with light painting. You can use aperture creatively in long-exposure light painting techniques. By using a narrower aperture and slower shutter speed, you can create a starburst-like effect with light sources or also achieve a unique light painting pattern and shape.
In conclusion, while aperture is a technical setting, you can also use it as a creative tool that will allow you to add further depth, mood, or visual impact to your images.
The best way to learn aperture is to go out and practice it and see how it interacts with the other two elements of the exposure triangle - shutter speed and ISO. Have fun!