Where to find the aperture control on your Canon

On most Canon cameras, you change aperture using the main dial — the rotating wheel on the top or back of the camera body. Which dial you use depends on your shooting mode and camera model, but the principle is the same: rotate the dial to adjust the f-number displayed on your screen or viewfinder.

If you're shooting in Aperture Priority mode (marked as Av on the mode dial), the main dial controls aperture directly. On Canon DSLRs like the EOS 5D or 80D, this is usually the dial on the top-right of the camera. On mirrorless models like the EOS R or M50, it's often the dial on the back. The exact location varies, so check your camera's quick-start guide if you're unsure which dial is which.

Key Takeaways

  • Switch your camera to Aperture Priority mode (Av) to control aperture independently, or use Manual mode (M) to control both aperture and shutter speed.
  • Rotate the main dial to change the f-number; lower numbers like f/1.8 let in more light, while higher numbers like f/16 let in less light and increase depth of field.
  • Watch the viewfinder or LCD screen as you rotate the dial to see the f-number change in real time.
  • If you're in Program mode or Auto mode, aperture is set automatically and the dial won't change it.

Using Aperture Priority mode for direct control

Aperture Priority mode is the easiest way to change aperture on purpose. Turn the mode dial on your camera to Av (or A on some models), then rotate the main dial to adjust the f-number. As you rotate, you'll see the number change on the LCD screen or in the viewfinder — lower numbers open the aperture wider, higher numbers close it down.

In this mode, you set the aperture and the camera automatically chooses the shutter speed to get the right exposure. This is useful when you care about depth of field (how much of the image is in focus) but don't want to think about shutter speed. If the camera can't find a shutter speed that works — for example, if you choose f/1.8 in bright sunlight — it will warn you on the screen.

Changing aperture in Manual mode

In Manual mode (M), you control both aperture and shutter speed. Turn the mode dial to M, then use the main dial to adjust aperture the same way you would in Aperture Priority mode. You'll also need to adjust shutter speed separately using a second dial or button (usually the quick control dial on the back).

Manual mode gives you the most control but requires you to think about both settings. Use it when you want to lock in a specific look — for example, shooting at f/2.8 with a 1-second shutter speed for a particular creative effect. If you're new to manual exposure, Aperture Priority is usually easier to start with.

What the f-numbers mean

The f-number (written as f/1.8, f/5.6, f/16, and so on) describes how wide the aperture opens. Lower numbers mean a wider opening that lets in more light. Higher numbers mean a narrower opening that lets in less light. The relationship is not linear — f/2.8 lets in twice as much light as f/4, and f/4 lets in twice as much as f/5.6.

A wider aperture (f/1.8 or f/2.8) creates a shallow depth of field, meaning the background blurs while the subject stays sharp. This is useful for portraits or isolating a subject. A narrower aperture (f/11 or f/16) creates a deep depth of field, keeping more of the scene in focus. This is useful for landscapes where you want everything sharp from foreground to background.

Your lens determines the widest aperture available. A kit lens might max out at f/3.5 or f/5.6, while a professional lens might open to f/1.4 or f/2.8. You can always stop down (use a higher f-number) to narrow the aperture, but you can't open wider than your lens allows.

Checking your current aperture setting

On Canon DSLRs, the current f-number appears in the viewfinder at the bottom of the frame and on the LCD screen on the back. On mirrorless cameras, it shows on the LCD screen and in the electronic viewfinder. As you rotate the main dial, watch this number change to confirm you're adjusting aperture and not another setting.

If you're in Program mode or Auto mode, the f-number will be displayed but won't change when you rotate the dial — the camera is controlling aperture automatically. Switch to Aperture Priority or Manual mode if you want to change it yourself.

Why aperture won't change

If you're rotating the dial and the f-number isn't changing, you're likely in a mode where aperture is automatic. Check the mode dial on top of your camera. If it's set to P (Program), Tv (Shutter Priority), or a scene mode like Portrait or Landscape, the camera controls aperture for you. Switch to Av (Aperture Priority) or M (Manual) to take control.

Another possibility is that you're rotating the wrong dial. On some Canon models, there are two dials that do different things. Check your camera's manual or quick-start guide to confirm which dial controls aperture in your specific model. If you're using an older film camera or a very compact model, the controls may be in a different location.

Frequently Asked Questions

What's the difference between f/2.8 and f/5.6?

f/2.8 opens the aperture wider and lets in four times as much light as f/5.6. It also creates a shallower depth of field, so the background blurs more. f/5.6 is narrower and keeps more of the scene in focus. Which you choose depends on whether you want a blurred background or sharp detail throughout the image.

Can I change aperture while recording video?

On most Canon DSLRs, you can rotate the main dial to change aperture during video recording, and the change happens smoothly. On some mirrorless models, you may need to use the touchscreen or a different button. Check your camera's video manual to confirm. Changing aperture during recording will change the exposure, so do it slowly to avoid jarring brightness shifts.

Why does my camera show a blinking f-number?

A blinking f-number usually means the camera can't achieve proper exposure with your current settings. In Aperture Priority mode, this often means the shutter speed would be too slow (risking blur) or too fast (the camera has a limit). Try opening the aperture wider (lower f-number) or increasing the ISO to let the camera use a faster shutter speed.

Does every Canon camera have an Av mode?

Most Canon DSLRs and mirrorless cameras have Aperture Priority mode, but some compact or entry-level models may not. If your camera doesn't have an Av mode, use Manual mode instead — you'll control aperture the same way, but you'll also need to set shutter speed yourself. Check your camera's mode dial to see what options are available.