Canon EOS-1D X Mark III EOS-1DX Mark III Advanced User Guide - Page 235

3. Recompose and take the picture. The AE lock exposure value and current exposure value are shown in real time at right in the viewfinder. When you are to take more pictures while maintaining the AE lock, keep holding down the < > button and press the shutter button to take another picture. Note AE lock is not possible with bulb exposures. AE Lock Effects Metering Mode Selection Selecting the AF Area and AF Point Automatic Selection Exposure value centered on the AF point in focus is locked. AE lock is applied at the center AF point. Manual Selection Exposure value centered on the selected AF point is locked. * When the < > is set and the lens's focus mode switch is set to < the exposure value weighted on the center AF point. >, AE lock is applied with 235