Why you should us AF-ON

Using the AF-ON back button to focus (rather than the shutter release) takes a while to get used to but is well worth the effort. To set it up, look for the Af-activation menu option and set it to ‘AF-ON only’. Setting the AF-ON button to focus and disabling the shutter release separates the action of focusing the camera and capturing the image. Once the camera is locked in focus, you can repeatedly press the shutter release without it changing.