To compose photographs with off-center subjects:
Focus: Position the subject in the focus frame and press the shutter button halfway to lock focus and exposure. Focus and exposure will remain locked while the shutter button is pressed halfway (AF/AE lock).
AEL/AFL button. The role played by the AEL/AFL button can be chosen using BUTTON/DIAL SETTING > FUNCTION (Fn) SETTING: choose from AE LOCK ONLY (pressing the AEL/AFL locks exposure but not focus), AF LOCK ONLY (pressing the AEL/AFL locks focus but not exposure), and AE/AF LOCK (pressing the AEL/AFL locks both focus and exposure).
Recompose: Keep the shutter button pressed halfway or keep the AFL/AEL button pressed.
Focus and/or exposure will remain locked while the AFL/AEL button is pressed, whether or not the shutter button is pressed halfway. If AE&AF ON/OFF SWITCH is selected for BUTTON/DIAL SETTING > AE/AF-LOCK MODE, focus and/or exposure lock when the button is pressed and remain locked until the button is pressed again.
Shoot: Press the button all the way down.
Although the camera boasts a high-precision autofocus system, it may be unable to focus on the subjects listed below.