Canon EOS 1D Mark II Instruction Manual page 151

C.Fn-12
1: Effective for close-up and telephoto shots to prevent camera shake
caused by the mirror's reflex action. See page 97 for the mirror
lockup procedure.
C.Fn-13
1: The selectable AF points are limited to 11. Spot metering is linked
to the active AF point. (p.81)
2: The selectable AF points are limited to 11. Spot metering is linked
to the center AF point. (p.81)
3: The selectable AF points are limited to 9. Spot metering is linked
to the active AF point. (p.81)
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The metering mode must be set to spot metering before it can be
linked to the AF point.
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If C.Fn-13-1/2 is set or cleared, the registered AF point (p.70) will be
replaced by the center AF point.
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Any metering mode besides spot metering can be used.
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With C.Fn-13-1/2/3, all 45 AF points will be available for automatic
selection.
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With C.Fn-13-1/3, FE lock is possible with any AF point you select.
C.Fn-14
0: Fully automatic flash photography for all conditions, from low light
to daylight fill-flash.
1: The flash exposure will be averaged over the Area AF ellipse. Since
automatic flash exposure compensation will not be executed, you may have
to set it yourself depending on the scene. This also applies if you use FE lock.
C.Fn-15
1: By using a slow sync speed, you can create a light trail following a
moving subject. The flash fires right before the shutter closes. This
Custom Function can be used to obtain 2nd-curtain sync effects
even with EX-series Speedlites which do not have this feature. If
an EX-series Speedlite having this feature is set for 2nd-curtain
sync, it will override this Custom Function.
Mirror lockup
Number of AF points/Spot metering
E-TTL II autoflash system
Shutter curtain synchronization
151