What Is Aperture on a Camera?

On this page (8 sections)

1. What is aperture on a camera lens?
2. Why does a lower f-number mean a wider opening?
3. How does aperture change background blur?
4. What aperture should you use for different photos?
5. How does aperture work with shutter speed and ISO?
6. Does every lens have the same maximum aperture?
7. Does aperture change how much of a photo is in focus?
8. Which camera aperture should you start with?

Aperture is the opening in a lens that controls how much light reaches the camera sensor. A lower f-number means a wider opening, more light, and often a softer background; a higher f-number means a narrower opening and less light.

Aperture also affects how much of the scene looks in focus. Once you understand the f-number scale, you can choose settings with more control over portraits, landscapes, movement, and dim rooms.

What is aperture on a camera lens?

Aperture is the adjustable opening inside the lens. The camera changes its size to control the light that reaches the sensor.

Aperture is written as an f-number, such as f/1.8, f/2, or f/8. The number can feel backward at first: a smaller f-number is a larger opening, while a larger f-number is a smaller opening.

The opening is one part of exposure, along with shutter speed and ISO. For a fuller view of those settings, read our guides to shutter speed and ISO on a camera.

Why does a lower f-number mean a wider opening?

The f-number describes the opening in relation to the lens's focal length. That relationship is why f/2 is wider than f/8, even though 2 is the smaller number.

A wider opening passes more light to the sensor. In dim light, that can help the camera use a faster shutter speed or a lower ISO, depending on the scene and the other settings.

A lens's maximum aperture is its widest available opening. For example, an f/1.8 lens can open wider than an f/2 lens, though the difference between those numbers is modest.

How does aperture change background blur?

A wider aperture can make the background look more blurred, especially when your subject is close and the background is farther away. This can make a portrait subject stand out from the scene.

A narrower aperture can keep more of the foreground and background in focus. It may suit a landscape, a group, or a scene where you want details across the frame to remain clear.

Aperture alone doesn't determine the look. Subject distance, background distance, focal length, and sensor format also affect how much blur you see.

Which lens aperture helps with portraits and low light?

A lens with a wide maximum aperture gives you more room to work in dim light and to soften the background. The Canon EF 50mm f/1.8 STM has a maximum aperture of f/1.8 and is compatible with Canon EOS DSLR cameras.

This is an EF-mount lens for DSLR cameras, so check your camera's mount before choosing it. If you're still deciding which camera type suits you, compare DSLR, mirrorless, and zoom cameras for beginners.

What aperture should you use for different photos?

Choose a wider aperture for more light or background blur, and a narrower aperture when you want more of the scene in focus. Start with the effect you want, then adjust shutter speed and ISO to get the exposure you need.

What aperture works for portraits?

For a portrait with a soft background, start with a low f-number if your lens allows it. Check focus carefully, since a very shallow area of focus can leave part of the face soft.

For a group, try a higher f-number so more faces can stay sharp. The best setting depends on how people are arranged and how far they are from the camera.

What aperture works for landscapes?

For a landscape with foreground and distant details, try a higher f-number than you would for a portrait. Review the image and adjust if important parts of the scene aren't sharp.

A higher f-number reduces the amount of light reaching the sensor. You may need a slower shutter speed or higher ISO to compensate, so keep the camera steady if the shutter speed drops.

What aperture works for action or dim rooms?

In low light, a wider aperture can help you keep a faster shutter speed. That can reduce motion blur, though the result also depends on how quickly your subject moves and how much light is available.

A lens with a wide maximum aperture can give you more choices in dim conditions. The Nikkor Z 40mm f/2 has a maximum aperture of f/2 and is compatible with FX and DX format Nikon Z-series mirrorless cameras.

On a DX-format Nikon Z camera, this lens has a field of view of 60mm. Consider that framing when choosing a lens.

How does aperture work with shutter speed and ISO?

Aperture, shutter speed, and ISO work together to control exposure. Changing one setting can affect how bright the photo looks or how it captures motion and detail.

A wider aperture lets in more light, which may allow a faster shutter speed. A narrower aperture lets in less light, so you may need a slower shutter speed or a higher ISO to keep the image bright.

Shutter speed controls how long the sensor receives light and how motion appears. ISO changes the camera's sensitivity setting; our guide to what ISO means on a camera explains when to adjust it.

Does every lens have the same maximum aperture?

No. Each lens has its own maximum aperture, and some zoom lenses have a maximum aperture that changes as you zoom.

Check the lens name and its specifications to find the widest opening it supports.

The f-number is one of the numbers printed on a lens. Our guide to what the numbers on a camera lens mean explains how to read them.

A lens's mount also matters: a wide aperture won't make it compatible with a camera it cannot attach to. The Sony FE 50mm f/1.8 is a 50mm lens for Sony E-mount cameras, with a maximum aperture of f/1.8.

Check your camera's mount before choosing this lens. Framing can also differ between camera formats.

Does aperture change how much of a photo is in focus?

Yes. A wider aperture often gives you a shallower area of focus, while a narrower aperture can keep more of the scene sharp.

This is often called depth of field.

Depth of field also depends on focus distance, focal length, and the distance between your subject and background. Move closer to your subject or place the background farther away, and the background may look softer.

If your subject's eyes or other important detail aren't sharp, try a higher f-number or move farther away. Take another photo and check the result before settling on a setting.

Which camera aperture should you start with?

Start with the effect you want: use a lower f-number for more light and background blur, or a higher f-number to keep more of the scene in focus. Then check exposure and focus, and adjust the other settings if needed.

If you use an EOS R-series camera, the Canon RF 50mm f/1.8 STM has a maximum aperture of f/1.8 and is compatible with the EOS R system.

This lens is compatible with EOS R-series cameras, including the EOS R100, EOS R50, and EOS R10. Check your camera model and mount before buying.

For another camera decision, see our guide to choosing a DSLR for beginners. Once you know which lens fits your camera, experiment with aperture in a familiar scene and review how the background and exposure change.

Frequently asked questions

What does aperture mean on a camera?

Aperture is the adjustable opening inside a lens that lets light reach the camera sensor. It is measured in f-stops, such as f/2.8 or f/8.

A smaller f-number means a wider opening and more light, while a larger f-number means a narrower opening and less light.

Is a higher or lower aperture better?

Neither is always better. A lower f-number lets in more light and can blur the background, which can help with portraits or dim scenes.

A higher f-number gives a narrower opening and can keep more of the scene in focus, which can suit landscapes or group photos.

What aperture should I use for portraits?

Try a low f-number if you want a softly blurred background, then check that the subject's face is in focus. The right setting depends on how many people are in the frame, how far they are from the camera, and how much of the scene you want sharp.

Does aperture affect shutter speed?

Yes. A wider aperture lets in more light, so the camera may be able to use a faster shutter speed for the same exposure.

A narrower aperture lets in less light, which may require a slower shutter speed or a higher ISO setting.