The BKT Button
Use the BKT button to choose the bracketing increment and number of shots in the bracketing program. Bracketing is used to vary exposure, flash level, white balance, or Active D‑Lighting (ADL) over a series of shots.
The role performed by the BKT button can be chosen using Custom Setting f3 .
The BKT button may be disabled in some shooting modes or when certain conditions apply.