Canon EOS 70D Operation Manual - Page 386

8: Custom Controls : Metering and AF start When you press the button assigned to this function, metering and AF are executed. : AF stop The AF will stop while you hold down the button assigned to this function. Convenient when you want to lock the focus during AI Servo AF. : ONE SHOT z AI SERVO You can switch the AF operation. In One-Shot AF mode, when you hold down the button to which this function is assigned, the camera switches to AI Servo AF mode. In the AI Servo AF mode, the camera switches to One-Shot AF mode only while you hold down the button. Convenient when you need to keep switching between One-Shot AF and AI Servo AF for a subject that keeps moving and stopping. : AF point direct selection During metering, you can select an AF point directly with without pressing the or button. : Metering start When you press the shutter button halfway, only exposure metering is performed. : AE lock/FE lock Normal shooting (No flash) When you press the button assigned to this function, you can lock the exposure (AE lock) during the metering. Convenient when you want to focus and meter the shot at different areas or when you want to take multiple shots at the same exposure setting. With flash During flash photography, pressing the button assigned to this function will fire a preflash and record the required flash output (FE lock). 386