On Canon EOS R series cameras, back button focus is set in the custom controls menu: assign autofocus to the AF-ON button and stop the half press of the shutter button from focusing. Exact menu names and numbers vary by model, so confirm the steps in your own camera’s manual.

How to Use Back Button Focus on Canon EOS R Cameras

What You Are Changing

By default, a half press of the shutter button triggers autofocus. Back button focus gives that job to AF-ON, a button near your thumb on the back of the body. After the change, the shutter button only releases the shutter, and you decide exactly when the camera focuses.

General Setup Steps

  1. Open the main menu and go to the custom controls section, often shown with a small gear or custom icon.
  2. Find the option for the shutter button half press, sometimes called the shutter button function. Change it so that it meters only and does not trigger autofocus. Some models let you choose metering and not AF, or metering plus another function.
  3. Check the function assigned to the AF-ON button. On many EOS R bodies, it already performs metering and autofocus. Leave it as is unless you want a different behavior.
  4. If you prefer another button, such as the multi-controller press or a custom button, assign AF-ON to it in the same menu.
  5. Set the focus mode to One-Shot for static subjects or Servo for moving subjects. Choose the area mode that suits your scene.
  6. Test with a few frames before important work. Aim at a subject, hold AF-ON until focus confirms, then press the shutter.

Using It in Practice

  • Static subjects: focus with AF-ON, release the button, recompose, and shoot. The focus distance stays where you put it.
  • Moving subjects: set Servo and hold AF-ON to track. Use subject detection options, such as people, animals or vehicles, if your model offers them.
  • Switching styles: some cameras allow saving settings to custom modes on the dial, so you can switch quickly between a back button setup and the default.

Tips for Better Results

  • Use a firm grip so that your thumb can reach the button without shifting your hand.
  • Combine tracking with a shutter speed that is fast enough for your subject. Roughly 1/500 and faster handles many moving subjects, as a first guide.
  • Take a few practice sessions around the house or the park before an event.
  • If a live view feature offers touch focus, remember that tapping the screen may still work independently of your button setup.

FAQ

Will the change affect video?

Video focus behavior may be controlled by separate settings, so look at the movie options in the menu and test before filming.

How do I go back to normal?

Return to the custom controls menu and restore the shutter half press to metering and autofocus. Many cameras also have a reset option for custom controls.

The Short Version

Assign focus to AF-ON, remove it from the shutter button, and choose One-Shot or Servo to match the subject. Check your own model’s manual for the exact menu names, then practice until the habit feels natural.