Focus/Exposure Lock

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).

If AE-LOCK, AF-LOCK, or AE/AF LOCK is assigned to the Fn button, the focus and/or exposure will lock while the Fn button is pressed and remain locked even when the shutter button is pressed halfway.
Recompose: Keep the shutter button pressed halfway or keep the Fn button pressed.

This process can be repeated as often as desired before the picture is taken.
Shoot: Press the button all the way down.

Autofocus

Although the camera boasts a high-precision autofocus system, it may be unable to focus on the subjects listed below.

Very shiny subjects such as mirrors or car bodies.
Subjects photographed through a window or other reflective object.
Dark subjects and subjects that absorb rather than reflect light, such as hair or fur.
Insubstantial subjects, such as smoke or flame.
Subjects that show little contrast with the background.
Subjects positioned in front of or behind a high-contrast object that is also in the focus frame (for example, a subject photographed against a backdrop of highly contrasting elements).