The f-number is a ratio involving the lens’s focal length and the diameter of the entrance pupil. This is why the numbers do not correspond directly to the physical diameter of the opening.

For a beginner, however, the practical rule is enough:

Lower f-number = wider aperture = more light.

Higher f-number = narrower aperture = less light.

How Aperture Affects Exposure

One of the most important functions of aperture is controlling exposure.

The camera’s exposure is affected by three primary controls:

• Aperture
• Shutter speed
• ISO

Together, these are often referred to as the exposure triangle.

Opening the aperture allows more light into the camera.

Closing the aperture allows less light into the camera.

For example, imagine that you are filming an interior scene in a dimly lit room. If you open the lens from f/5.6 to f/2.8, you allow significantly more light to reach the sensor. This may allow you to maintain a useful exposure without increasing ISO as much.

However, changing aperture does not simply make an image brighter or darker. It also changes the visual characteristics of the shot.

That is why filmmakers should not think of aperture as an exposure control alone.

Changing aperture can change the relationship between the subject and the background, the amount of the scene that remains sharp, and ultimately what the audience notices.

Aperture and Depth of Field

One of the most important relationships to understand in photography and cinematography is the relationship between aperture and depth of field.

Depth of field refers to the range of distance in a scene that appears acceptably sharp.

A wide aperture generally produces a shallower depth of field.

A narrow aperture generally produces a deeper depth of field.

For example:

f/1.4 → shallow depth of field

f/2.8 → relatively shallow depth of field

f/8 → deeper depth of field

f/16 → very deep depth of field

This is one reason filmmakers often use wide apertures when they want to separate a character from the background.

However, aperture is only one part of the equation.

Depth of field is also influenced by:

• Aperture
• Focal length
• Camera-to-subject distance
• Sensor or film format

This is where your choice of lens becomes important.

If you want to understand how focal length and other characteristics influence the image, see our guide to Know Your Lenses.

Wide Aperture vs. Narrow Aperture

Understanding the difference between wide and narrow apertures makes it easier to predict how changing the f-stop will affect your shot.

Wide Aperture

A wide aperture includes settings such as:

• f/1.4
• f/1.8
• f/2
• f/2.8

A wide aperture allows more light into the camera and generally produces a shallower depth of field.

This can be useful when you want to:

• Isolate a subject
• Create a soft or blurred background
• Draw attention to a character
• Shoot in lower-light conditions
• Create a strong separation between foreground and background

Imagine a close-up of a character standing several feet in front of a busy street. At a wide aperture, the character can remain relatively sharp while the lights, cars, and people behind them become soft shapes.

The environment is still there, but it becomes less visually dominant.

Narrow Aperture

A narrow aperture includes settings such as:

• f/8
• f/11
• f/16

A narrow aperture allows less light into the camera but generally produces a greater depth of field.

This can be useful when you want more of the scene to remain recognizable and sharp.

For example, imagine a wide shot showing a character in a landscape. You may want both the character and the surrounding environment to contribute important information to the composition.

In that situation, a deeper depth of field can help keep the environment visually significant.

The important point is that neither a wide nor a narrow aperture is inherently better.

The appropriate aperture depends on what you want the image to communicate.

Aperture and Bokeh

Aperture is closely associated with bokeh, the visual appearance of out-of-focus areas in an image.

A wide aperture can create strongly blurred areas behind a subject, making the background appear soft and separated from the plane of focus.

However, aperture is not the only factor that affects the appearance of out-of-focus areas.

Bokeh is also influenced by factors such as:

• Focal length
• Distance between the subject and background
• Distance between the camera and subject
• Lens design
• The shape of the lens’s aperture

This is another reason why two lenses set to the same aperture can produce noticeably different-looking images.

For filmmakers, background blur is not simply a visual effect. It can influence how the audience reads the frame.

A sharply defined background may provide information about where a character is and what is happening around them.

A heavily blurred background can reduce distractions and direct attention toward the character.

How Aperture Changes the Look of a Shot

This is where aperture becomes much more interesting for filmmakers.

Instead of thinking only about the technical question of “How much light do I need?”, ask:

What should the audience be looking at?

Imagine the same character standing in the same location and being filmed with the same lens.

Shooting at f/1.4

At a very wide aperture, the character can be strongly separated from the environment.

The background may become heavily blurred, creating a shallow visual field.

This can make the image feel intimate and direct because the character becomes the dominant visual element.

Shooting at f/2.8

The character can still be separated from the background, but more environmental information may remain visible.

This can create a balance between character and location.

Shooting at f/5.6

More of the environment begins to contribute to the image.

If the location is important to the story, this can be useful because the audience can read more visual information around the character.

Shooting at f/11

A much larger portion of the composition can remain within the depth of field.

This can be particularly useful when the spatial relationship between multiple subjects or elements of the environment is important.

The difference between these settings is therefore not simply technical.

It is a difference in visual storytelling.

Aperture in Filmmaking

In filmmaking, aperture is one of the tools cinematographers use to shape the visual language of a scene.

A cinematographer may choose an aperture based on several considerations:

• Desired depth of field
• Available light
• Subject isolation
• Relationship between character and environment
• Lens characteristics
• Overall visual style
• Exposure requirements

Consider a scene in which a character discovers something important in a crowded room.

If the cinematographer uses a relatively wide aperture, the character can be visually separated from the surrounding crowd. The audience’s attention can be directed toward the character while the environment becomes less prominent.

Now imagine a different scene in which the location itself is essential to the story.

A deeper depth of field may allow the audience to understand the relationship between the character and the surrounding environment.

The aperture has therefore become part of the storytelling.

Aperture and Low-Light Filmmaking

Aperture also becomes particularly important when working with limited light.

A wider aperture allows more light to reach the sensor, which can make it possible to achieve a desired exposure in darker conditions.

For example, a filmmaker shooting an interior scene at night may choose a wider aperture to gather more available light.

However, opening the aperture also reduces depth of field.

This creates a creative and technical trade-off.

You may gain more light, but you may also have less depth of field to work with.

For a moving actor, this can make focus more demanding.

This is why choosing an aperture is rarely about solving one problem. Cinematography often involves balancing several competing requirements.

How to Choose the Right Aperture

There is no single “best” aperture.

The right aperture depends on the subject, lighting, lens, composition, movement, and visual intention of the shot.

For Portraits

A wide aperture can help separate the subject from the background.

This is particularly useful when the background contains distracting elements that are not important to the image.

For Landscapes

A narrower aperture can provide greater depth of field, helping more of the scene remain sharp.

However, simply selecting the smallest possible aperture is not always the goal. The aperture should be chosen according to the desired image and the characteristics of the lens.

For Group Shots

When multiple people are positioned at different distances from the camera, a wider aperture can make it difficult to keep everyone within the desired depth of field.

A narrower aperture may provide more room for error.

For Low-Light Scenes

A wider aperture can allow more light to reach the sensor, making it useful when working with limited illumination.

But the resulting shallower depth of field must also be considered.

For Cinematic Scenes

For filmmaking, the most useful question is often not:

“What aperture should I use?”

Instead, ask:

“What relationship do I want between my subject and the environment?”

If the character should dominate the frame, a shallower depth of field may help.

If the environment provides important storytelling information, a deeper depth of field may be more appropriate.

Aperture should support the visual idea of the shot rather than dictate it.

Common Aperture Mistakes Beginners Make

Mistake 1: Thinking f/16 Is Wider Than f/2.8

The numbers can be confusing at first.

Remember:

Lower f-number = wider aperture.

Higher f-number = narrower aperture.

Mistake 2: Always Shooting Wide Open

A very wide aperture can produce beautiful background separation, but that does not mean it is always the right choice.

If the story requires the audience to understand the environment, excessive background blur can remove useful visual information.

Mistake 3: Assuming Aperture Alone Controls Depth of Field

Aperture is important, but focal length, camera-to-subject distance, and sensor or film format also influence depth of field.

Changing lenses or moving the camera can therefore change the image even when the aperture remains the same.

Mistake 4: Using a Very Wide Aperture When Multiple Subjects Need to Be Sharp

If two actors are positioned at significantly different distances from the camera, an extremely shallow depth of field may make it difficult to keep both within focus.

A deeper depth of field may be more appropriate.

Mistake 5: Choosing Aperture Only for Exposure

Exposure matters, but cinematography is also about controlling the appearance and meaning of the image.

Changing aperture can change what the audience sees, what they ignore, and how strongly a subject is separated from its environment.

Aperture, Lenses and Cinematography

Aperture does not exist in isolation.

Your choice of lens, focal length, camera position, and aperture all work together to determine the visual character of a shot.

A useful way to think about the relationship is:

Lens → Focal Length → Aperture → Depth of Field → Visual Storytelling

For example, a wide-angle lens at f/2.8 can produce a very different image from a telephoto lens at f/2.8.

Both lenses may have the same aperture setting, but their focal lengths, perspective relationships, and depth-of-field characteristics can produce very different results.

This is why understanding aperture should go hand in hand with understanding lenses.

If you are learning cinematography, don’t think of aperture as an isolated camera setting. Think of it as one part of a larger visual system.

FAQ: Aperture in Photography and Filmmaking

What is aperture in photography?

Aperture is the adjustable opening inside a camera lens that controls how much light reaches the camera’s sensor or film. It also influences depth of field and therefore how much of an image appears to be in focus.

What does aperture do?

Aperture controls the amount of light entering the camera and influences depth of field. A wider aperture allows more light in and generally creates a shallower depth of field, while a narrower aperture allows less light in and generally creates a deeper depth of field.

What is an f-stop?

An f-stop is the numerical representation used to describe a lens’s aperture. Common settings include f/1.4, f/2.8, f/4, f/5.6, f/8, and f/11.

Is f/1.8 better than f/8?

Neither aperture is inherently better. f/1.8 provides a wider aperture, more light, and generally a shallower depth of field. f/8 provides a narrower aperture and generally a deeper depth of field. The appropriate choice depends on the shot.

Does a lower f-stop mean more light?

Yes. A lower f-number represents a wider aperture, which allows more light to enter the camera.

How does aperture affect depth of field?

A wider aperture generally produces a shallower depth of field, while a narrower aperture generally produces a deeper depth of field. Depth of field is also influenced by focal length, camera-to-subject distance, and sensor or film format.

What aperture should I use for filmmaking?

There is no single aperture that is right for every film or scene. Choose an aperture based on the desired depth of field, available light, subject movement, lens characteristics, and the visual relationship you want between the characters and their environment.

What is the difference between aperture and f-stop?

Aperture refers to the physical opening in the lens. The f-stop is the numerical system used to describe the size of that opening relative to the lens’s focal length.

Does aperture affect video?

Yes. Aperture affects the amount of light reaching the camera’s sensor and influences depth of field. In filmmaking, these characteristics can significantly affect the visual appearance and storytelling function of a shot.

Final Thoughts

Aperture begins as a technical concept, but it quickly becomes a creative one.

At a basic level, aperture controls how much light enters the camera. But once you understand f-stops, you can start using aperture deliberately to control depth of field, subject isolation, background blur, and the visual relationship between characters and their surroundings.

For a filmmaker, that distinction matters.

The goal is not simply to know that f/2.8 lets in more light than f/8.

The goal is to understand what that difference can do for your image.

Sometimes you want the audience to see only the character.

Sometimes you want them to see the entire world surrounding that character.

Aperture gives you another way to make that decision.