How To Change The F Stop On A Canon
Changing the f-stop on a Canon camera controls the size of your lens aperture to manage both exposure and depth of field. The exact method depends on your camera's shooting mode, ranging from turning the main dial in Manual or Aperture Priority to adjusting sub-dials or touchscreen menus on entry-level models.
Essential Prerequisites for Aperture Control
Mastering your camera's aperture mechanism requires understanding how light enters the lens barrel through variable physical blades. Before adjusting your f-stop settings in the field, verify your equipment status and camera mode dial to ensure the camera body has full electronic control over the lens diaphragm.
- Essential Gear: Canon DSLR or mirrorless camera body (such as an EOS Rebel, EOS 6D, or EOS R series), an electronically communicative Canon EF, EF-S, or RF mount lens, and a fully charged LP-E series battery.
- Prerequisite Knowledge: Familiarity with the exposure triangle (ISO, shutter speed, and aperture), the physical location of the camera's main dial, and the difference between manual exposure mode and semi-automated modes.
- Time and Scope: Estimated learning and execution time of 5 to 10 minutes to master the dial layouts across different Canon camera bodies.
Step-by-Step Guide to Adjusting Canon Aperture Settings
Step 1: Switch Your Camera to Manual or Aperture Priority Mode
Turn the top physical mode dial on your Canon camera to either M (Manual Mode) or Av (Aperture Value mode). In the Av mode, you choose the f-stop manually while the camera automatically calculates the matching shutter speed. In Manual mode, you retain full independent control over both the f-stop and the shutter speed.
Pro-Tip: If your mode dial is locked, press and hold the center mode lock release button (found on higher-end EOS models like the 5D or 80D) while turning the dial.
Step 2: Locate the Main Electronic Dial
Find the ribbed, knurled electronic control dial located on the top right of your camera body, typically positioned just behind the shutter release button. Your index finger should rest naturally on this dial when gripping the handgrip. Rotating this main dial is the universal default action for changing exposure values on most Canon cameras.
Step 3: Rotate the Dial to Modify the F-Stop Value
Look through the optical viewfinder or check the rear LCD screen while rotating the main dial clockwise or counter-clockwise. You will see the f-number (displayed as a letter F followed by a numerical value like f/2.8, f/4, or f/8) change in real-time. Rotating the dial in one direction opens the aperture wider (decreasing the f-number), while rotating it the opposite way narrows the opening (increasing the f-number).
Warning: If rotating the main dial does not change the f-stop, ensure the power switch is clicked past the ON position to the secondary multi-function lock line (if your model has one), which prevents accidental dial adjustments.
Step 4: Utilize the Rear Quick Control Dial (Advanced and Mirrorless Bodies)
If you are using a Canon two-dial system (such as the EOS 80D, 6D Mark II, 5D series, or EOS R mirrorless bodies), look for the large rotating wheel on the back of the camera body. In Manual (M) mode, the top dial controls the shutter speed, while this rear Quick Control Dial controls the aperture f-stop value. Ensure the power switch is toggled fully on so the rear dial is active.
Step 5: Adjust Aperture on Entry-Level Models via the AV Button
If you are shooting in Manual (M) mode on an entry-level Canon Rebel (such as the T7, T8i, or SL3) which lacks a rear control wheel, hold down the physical Av+/- button on the top right rear of the camera while simultaneously rotating the single top main dial. This action forces the top dial to adjust the aperture instead of the shutter speed.
The Lens - Photography: What, How, Why
Canon Aperture Range and Photographic Impact
| F-Stop Value | Aperture Opening Size | Depth of Field | Primary Photographic Use Case |
|---|---|---|---|
| f/1.2 - f/2.0 | Extremely Wide | Very Shallow | Low-light conditions, extreme background blur (bokeh) for portraits |
| f/2.8 - f/4 | Wide | Shallow | Standard portraits, street photography, subject separation |
| f/5.6 - f/8 | Medium | Moderate | Group shots, general travel photography, sharp overall rendering |
| f/11 - f/16 | Narrow | Deep | Landscapes, architecture, ensuring sharp focus from foreground to background |
| f/22 - f/32 | Extremely Narrow | Maximum | Bright daylight long exposures (risk of diffraction softness) |
Troubleshooting Common Aperture Adjustment Issues
- Root Cause: The lens aperture is locked at its minimum physical setting due to a poor electronic connection between the lens contacts and the camera mount.
- Actionable Fix: Turn off the camera, detach the lens, wipe the gold metal communication pins clean with a microfibre cloth, and re-attach the lens until it clicks securely into place.
- Root Cause: A variable aperture zoom lens (such as an 18-55mm f/3.5-5.6) refuses to let you select a wide f-stop like f/3.5 while zoomed in.
- Actionable Fix: Understand that lens physics dictate maximum aperture limits as you zoom in; zoom out to the widest focal length if you need the lowest possible f-stop number.
- Root Cause: You are trying to change the f-stop while the camera is recording video or processing a burst image buffer.
- Actionable Fix: Wait for the orange access light on the back of the camera to stop blinking, indicating the buffer has cleared, before attempting further setting changes.
Frequently Asked Questions
Why won't my Canon camera let me change the f-stop?
This typically happens because the camera is set to a fully automatic mode (such as Scene Intelligent Auto or Program Auto), which locks manual exposure adjustments. Switch your top mode dial to Aperture Priority (Av) or Manual (M) to regain full control over the f-stop.
How does the f-stop affect background blur?
A lower f-number (such as f/1.8) represents a wide physical aperture opening, which creates a very shallow depth of field that isolates your subject against a blurred background. Conversely, a higher f-number (such as f/11) creates a smaller opening, keeping both your subject and the background in sharp focus.
What is the difference between f-stop and aperture?
Aperture refers to the physical opening inside the lens diaphragm through which light travels. The f-stop is the mathematical ratio used to measure that opening, calculated as the focal length divided by the effective diameter of the aperture.
How do I change the aperture on a Canon mirrorless camera like the EOS R?
On Canon mirrorless bodies, you can use the standard top dial, the rear control ring, or even assign aperture control to the customizable control ring built directly onto RF lenses. You can also tap the Q menu on the touchscreen interface to adjust the value visually.
Does changing the f-stop affect my exposure?
Yes, because the aperture controls the volume of light passing through the lens. Making the f-stop larger (using a lower number like f/2) lets in more light and brightens the image, while making it smaller (using a higher number like f/11) restricts light and darkens the image.
Master your Canon camera settings today and elevate your photography by exploring our in-depth guides on shutter speed and ISO management.
