How Back-Button Focusing Works: Taking the Nikon Z 7 and Sony α6300 as Examples

What is Back-Button Focusing

Back-button focusing generally refers to assigning the autofocus activation function to a button other than the shutter, such as the AF-ON on the back of the camera; whether or not to disable half-press shutter focusing depends on the camera's menu settings. This changes the way focus is controlled but does not automatically change the focus mode or guarantee sharper photos. [G-BB-01, G-BB-02]

Example with Sony ILCE-6300

The Sony ILCE-6300 manual states that you can assign AF On to a custom button and use that button to start autofocus; focus mode settings still apply. The manual also notes: to focus based on an expected subject position at a specific shooting distance, AF w/ shutter and Pre-AF can be set to Off. Menu names and feature ranges may differ for other Sony models, and should be operated according to the respective manual. [G-BB-01, G-BB-02]

Example with Nikon Z 7

Nikon Z 7's AF activation settings provide an AF-ON only option. Once enabled, a half-press of the shutter no longer activates focusing; AF-ON or other controls assigned to AF-ON must be used. Menus, button assignments, and shutter release conditions may vary by model, so the camera manual should be consulted before making changes. [G-BB-03]

Perform an Operation Check Before Switching

After modifying the settings, first take several test shots of both stationary and moving subjects: confirm which button activates focus, whether a half-press of the shutter still triggers focusing, how current AF-S / AF-C modes work, and whether focus is held after releasing the button. If the camera will be used by someone else, also explain that the focus button has been changed. The above are suggested checks to avoid misuse, not performance or success guarantees. [G-BB-01, G-BB-02, G-BB-03]