Learn How to Change Aperture on Canon Cameras

Understanding Aperture and Its Role in Photography

Aperture is one of the three fundamental elements that control how your photographs look, alongside shutter speed and ISO. The aperture is an opening inside your camera lens that allows light to enter the camera body. Think of it like the pupil of your eye—it can expand to let in more light or contract to let in less light. On Canon cameras, the aperture opening is measured in f-stops, which may look like numbers such as f/1.8, f/4, f/8, or f/16.

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The confusing part about aperture numbers is that they work backwards from what you might expect. A smaller f-number, such as f/1.8, means the aperture opening is actually larger and lets in more light. A larger f-number, such as f/16, means the aperture opening is smaller and lets in less light. This backwards numbering system comes from the mathematical relationship between the aperture diameter and the lens focal length, which photographers have used for over a century.

Aperture affects your images in multiple important ways. First, it controls the amount of light that reaches your camera's sensor. This means changing your aperture directly impacts whether your photo appears bright or dark. Second, aperture controls depth of field, which is how much of your image appears in sharp focus. A wide aperture like f/1.8 creates a shallow depth of field, making the background blurry while keeping your subject sharp. A narrow aperture like f/16 creates a deep depth of field, keeping much more of the scene in focus from front to back.

Understanding aperture is essential before you attempt to change it on your Canon camera. Different situations call for different aperture settings. Portrait photography often uses wide apertures to blur the background, while landscape photography typically uses narrow apertures to keep everything in focus. Learning to change and control aperture gives you significant creative control over your photographs.

Practical Takeaway: Before adjusting aperture on your Canon, remember that smaller f-numbers mean larger openings and more light, while larger f-numbers mean smaller openings and less light. The aperture you choose directly affects both brightness and focus in your final image.

Locating the Aperture Controls on Your Canon Camera

Canon produces many different camera models, and the physical controls vary somewhat between them. However, most Canon DSLR and mirrorless cameras share similar systems for changing aperture. The primary way to adjust aperture on Canon cameras is through a dial or wheel, typically located on the back of the camera near your thumb when holding it in shooting position. This is often called the main dial or command dial.

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On Canon EOS DSLR models like the Canon EOS 5D Mark IV, EOS 80D, and EOS Rebel T8i, you'll find the main dial on the back right side of the camera body. This dial is usually textured with ridges to give you better grip and control. The dial rotates freely and has numbers or markings around its edge. When you look at the top of your camera, you'll also notice a shutter speed dial that sits above the viewfinder. These two dials work together to control exposure.

For Canon mirrorless cameras like the EOS R series, the dial layout is slightly different, but the principle remains the same. The main control dial is still positioned conveniently for your thumb. Canon designed these controls to be accessible without moving your eye away from the viewfinder, allowing you to keep shooting while making adjustments.

Beyond the physical dials, you'll also use the mode dial on the top of your camera. This dial has settings like Auto, Program (P), Aperture Priority (Av), Shutter Priority (Tv), and Manual (M). The Aperture Priority mode is the most common setting for photographers who want to change aperture while letting the camera handle shutter speed automatically. You'll rotate the top mode dial to align "Av" with a specific index mark on the camera body.

Many Canon cameras also include a quick control button on the back that allows you to access aperture settings without using the dials. These buttons often look like four-directional arrows surrounding a center button. Pressing this button opens a menu where you can select and adjust aperture settings using the main dial.

Practical Takeaway: Locate your main dial on the back of your camera and your mode dial on the top. If you're unsure where these are, consult your camera's instruction manual or look for the "Av" marking on your top mode dial—this is your starting point for aperture control.

Using Aperture Priority Mode to Change Aperture Settings

Aperture Priority mode, marked as "Av" on your Canon camera's mode dial, is the most straightforward method for photographers who want to control aperture while maintaining proper exposure. When you set your camera to Aperture Priority mode, you choose the aperture value you want to use, and the camera automatically calculates the correct shutter speed to achieve a properly exposed image. This mode is ideal when you have a specific creative vision for depth of field but want the camera to handle the technical exposure calculations.

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To switch to Aperture Priority mode, hold down the mode dial lock button on the top of your camera (usually located near the mode dial itself) and rotate the dial until "Av" aligns with the index mark. Release the button. Once you're in Aperture Priority mode, you'll notice that the shutter speed display on the back of your camera or in the viewfinder will change as you adjust the aperture.

Next, rotate the main dial on the back of your camera to change the aperture value. As you rotate the dial, you'll see the f-number change on your LCD screen or in the viewfinder. Rotating the dial one direction may increase the f-number (making it smaller and narrowing the aperture), while rotating it the other direction may decrease the f-number (making it larger and widening the aperture). The exact direction depends on your specific Canon model, so experiment or check your manual.

Canon cameras typically display aperture values in stops, which represent standard increments in light exposure. Common stops are f/1.8, f/2.8, f/4, f/5.6, f/8, f/11, and f/16. However, many modern Canon cameras also allow you to set aperture in one-third stop increments, giving you more precise control. For example, between f/2.8 and f/4, you might also see f/3.2 and f/3.5 available as options.

As you change the aperture, the camera automatically adjusts the shutter speed to maintain correct exposure. If you increase the aperture (lower f-number), the camera will increase the shutter speed to compensate for the extra light coming in. If you decrease the aperture (higher f-number), the camera will lower the shutter speed to allow more time for light to accumulate. This automatic compensation keeps your image brightness consistent while you focus on creative decisions about depth of field.

Practical Takeaway: Use Aperture Priority mode when you want to control depth of field. Set your mode dial to "Av," then rotate the main dial to select your desired f-number. Watch the shutter speed display change automatically as you adjust aperture, ensuring your image stays properly exposed.

Changing Aperture in Manual Mode for Complete Control

For photographers who want total control over both aperture and shutter speed, Manual mode (marked as "M" on the mode dial) offers complete exposure control. In Manual mode, you independently set both the aperture and shutter speed, and the camera does not make automatic adjustments. This mode requires more technical knowledge but gives you maximum creative control.

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To switch to Manual mode, hold the mode dial lock button and rotate the dial until "M" aligns with the index mark. In Manual mode, the same main dial on the back of your camera that controls aperture will also control shutter speed, but you'll switch between them using a specific button. On most Canon cameras, holding the ISO button or the metering mode button while rotating the main dial will change the shutter speed, while rotating the main dial without holding any button will change the aperture.

Many Canon cameras have an exposure compensation meter displayed in your viewfinder or on the back LCD screen. This meter shows you whether your current aperture and shutter speed combination will result in an overexposed (too bright) image, underexposed (too dark) image, or properly exposed image.