Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (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.
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