Replacing The Date/Time Battery; Remove The Battery - Canon MARK III EOS-1 DS Instruction Manual

Replacing the Date/Time Battery

The date/time (back-up) battery maintains the camera's date and time.
Its service life is about 5 years. If the date/time is reset when the battery
is replaced, replace the back-up battery with a new CR2025 lithium
battery as described below.
The date/time setting will also be reset, so be sure to set the
correct date/time.
(+)
For the date/time battery, be sure to use a CR2025 lithium battery.
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Set the power switch to <2>
1
and remove the battery pack.
The back-up battery is on the ceiling
of the battery compartment.
Remove the back-up battery
2
cover.
Use a small screwdriver to loosen the
screw and remove the cover.
Be careful not to lose the cover and screw.

Remove the battery.

3
Install a new back-up battery.
4
The plus side of the battery must face
up.
Attach the cover.
5