Canon EOS-1D X Mark III EOS-1DX Mark III Advanced User Guide - Page 766

4. Set daylight saving time. Set it as necessary. Turn the < > dial to select [ ], then press < >. Turn the < > dial to select [ ], then press < >. When the daylight saving time is set to [ ], the time set in step 3 will advance by 1 hour. If [ ] is set, the daylight saving time will be canceled and the time will go back by 1 hour. 5. Exit the setting. Turn the < > dial to select [OK]. Caution The date, time, and time zone settings may be reset when the camera is stored without the battery, when the battery is exhausted, or when it is exposed to freezing temperatures for an extended period. If this happens, set them once again. After changing [Zone/Time difference], check that the correct date/time are set. When you will use [Sync time between cameras] over a wired LAN or with a Wireless File Transmitter, use other EOS-1D X Mark III cameras. [Sync time between cameras] cannot be used with different models. 766