Canon 600EXII-RT Instruction Manual page 126

f Flash Firing Restriction due to Temperature Increase
Do not open or close the battery compartment cover while flash firing is
being restricted. Doing so is very dangerous since the flash firing
restriction is canceled.
Even when level 1 warning is not displayed, the firing interval will be
extended as the flash head begins to heat up.
If level 2 warning is displayed, allow a rest time for at least 40 min.
Even if you stop flash firing after level 1 warning is displayed, level 2
warning may be displayed.
If flash photography is performed in high temperatures, the firing
restrictions may be activated before the number of flashes listed in the
table on the preceding page is fired.
For cautions on the number of flash firings, see page 17 (continuous
flashes), page 42 (stroboscopic flash), or page 47 (modeling flash).
The Speedlite may not fire in rare cases due to environmental factors
such as temperature rise.
The number of continuous flashes until the warning is displayed on the
preceding page is the number when the 600EX II-RT is used by itself and
when the Compact Battery Pack CP-E4N (sold separately) is used
together with the 600EX II-RT. When an external power source other
than the CP-E4N is used, the number of continuous flashes until the
warning (level 1) is displayed becomes fewer.
When the bounce adapter is used, when the color filter is used, and
when both the bounce adapter and color filter are used together, the
number of continuous flashes until the warning is displayed becomes
slightly fewer.
When C.Fn-20-0 is set (p.116), the warning beep does not sound even
when flash firing is restricted.
When C.Fn-22-1 is set (p.117), the warning with red illumination of the
LCD panel will not be displayed even if the temperature of the flash head
rises.
When using Compact Battery Pack CP-E4N (sold separately), also refer
to the CP-E4N Instruction Manual.
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