Where to find the aperture setting on your Canon

On most Canon cameras, you control aperture using the Mode dial — the rotating ring on top of the camera body. Turn it to Av (Aperture Priority mode). Once you're in Av mode, use the Main dial (the textured wheel on the back right of the camera) to change the f-number. Turning the dial one direction increases the number (smaller opening, less light), and turning it the other direction decreases the number (larger opening, more light).

If your camera has a Quick Control screen, you can also change aperture by pressing the Q button (usually on the back left), then using the arrow keys to highlight the aperture value and turning the Main dial to adjust it. This works in Av mode and also in Manual (M) mode, where you control both aperture and shutter speed yourself.

The viewfinder or LCD screen will show you the current f-number as you adjust it — you'll see something like f/5.6 or f/2.8. The number updates in real time so you can see exactly what you're setting before you take the shot.

Key Takeaways

  • Switch your Mode dial to Av (Aperture Priority) to control aperture while the camera handles shutter speed automatically.
  • Use the Main dial on the back of the camera to change the f-number up or down, with lower numbers meaning a wider opening and more light.
  • You can also adjust aperture through the Quick Control screen by pressing Q and using the arrow keys, then turning the Main dial.
  • In Manual mode, you control both aperture and shutter speed, giving you full control but requiring you to set both values yourself.

Understanding f-numbers and what they do

The f-number (like f/2.8, f/5.6, f/16) tells you how wide the aperture opens. Lower numbers mean a wider opening — f/2.8 is much wider than f/16. A wider opening lets in more light, which is useful in dim rooms or outdoors at dusk. A narrower opening (higher f-number) lets in less light but keeps more of your scene in sharp focus from front to back.

Your specific Canon model can only open to a certain minimum f-number and close to a certain maximum. A kit lens might range from f/3.5 to f/5.6. A professional lens might go from f/2.8 to f/32. When you turn the Main dial and reach the limit of what your lens can do, the camera stops changing the number — you've hit the physical edge of that lens's capability.

The difference between Av mode and Manual mode

In Av (Aperture Priority) mode, you set the aperture and the camera automatically chooses the shutter speed to get the right exposure. This is the easiest way to control depth of field (how much of your image is in focus) without having to think about light metering. You pick the f-number you want, and the camera does the math.

In Manual (M) mode, you set both the aperture and the shutter speed yourself. The camera shows you a light meter in the viewfinder or on the LCD screen, but it doesn't force any settings on you. Manual mode gives you complete control but requires you to understand how shutter speed and aperture work together. If you set f/2.8 in bright sunlight without a fast enough shutter speed, your image will be overexposed (too bright).

For most people learning to control aperture, Av mode is the better starting point. You get to focus on understanding aperture and depth of field without juggling shutter speed at the same time.

What happens when you change aperture

When you widen the aperture (lower the f-number), more light enters the camera, so the background and foreground become blurrier — this is called shallow depth of field. A portrait shot at f/2.8 will have a soft, out-of-focus background that makes the subject stand out. The same portrait shot at f/16 will have the background sharp and detailed.

Narrowing the aperture (raising the f-number) keeps more of the scene in focus from near to far. Landscape photographers often use f/11 or f/16 so that mountains in the distance and rocks in the foreground are all sharp. Product photographers might use f/8 or f/11 so the entire object is in focus.

In Av mode, when you widen the aperture, the camera automatically speeds up the shutter to avoid overexposure. When you narrow the aperture, the camera automatically slows down the shutter to let in enough light. This is why Av mode is useful — the camera keeps your exposure balanced while you focus on the depth of field you want.

Checking your current aperture setting

Look at the LCD screen on the back of your camera or through the viewfinder. The f-number appears in the display — usually in the bottom or side of the frame. On most Canon models, it shows as a number like f/5.6 or f/2.8. If you're in Av mode, you'll also see the shutter speed the camera chose displayed right next to it.

If you're not sure whether you're in Av mode, look at the Mode dial on top of the camera. The indicator line or dot should point to the Av symbol. If it points to something else (P, Tv, M, or a scene icon), you're in a different mode and aperture changes may not work the way described here.

Common mistakes when adjusting aperture

The most common mistake is turning the dial in the wrong direction and getting confused about which way makes the aperture wider or narrower. There's no universal rule — it depends on your specific Canon model. The best way to learn is to watch the f-number on the screen as you turn the dial. If it's going the direction you don't want, turn the dial the other way.

Another mistake is forgetting to switch to Av or M mode before trying to adjust aperture. If you're in Program (P) mode or a scene mode (like Portrait or Landscape), the camera won't let you change the aperture — it controls everything automatically. The Mode dial must be set to Av or M.

A third mistake is not realizing that your lens has physical limits. If you're trying to shoot at f/1.8 but your lens only opens to f/3.5, the camera can't do it. The f-number won't change no matter how much you turn the dial. Check your lens's specifications to know what range it supports.

Frequently Asked Questions

Why does my aperture number not change when I turn the dial?

You're likely in a mode that doesn't let you control aperture manually. Switch the Mode dial to Av or M. If you're already in Av or M and the number still won't change, you may have reached the physical limit of your lens — most lenses can't open wider than a certain f-number or close narrower than a certain f-number.

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

f/2.8 is a much wider opening that lets in about four times more light than f/5.6. At f/2.8, the background will be much blurrier. At f/5.6, more of the scene will be in focus. Lower numbers always mean wider openings and more background blur.

Should I use a wide aperture or a narrow aperture?

It depends on what you're shooting. For portraits, use a wide aperture (f/2.8 or f/4) to blur the background and make the person stand out. For landscapes, use a narrow aperture (f/11 or f/16) to keep everything sharp. For everyday photos, f/5.6 to f/8 is a good middle ground.

Does aperture affect how bright my photo is?

Yes, but only if you're in Manual mode. In Av mode, the camera automatically adjusts shutter speed to keep brightness consistent as you change aperture. In Manual mode, widening the aperture makes the image brighter, and narrowing it makes the image darker — you have to adjust shutter speed to compensate.