Canon Speedlite 600 EX-RT User Manual (en, zh)

When continuous flash, stroboscopic flash or modeling flash is repeatedly fired 
in short intervals, the temperature of the flash head may increase. When 
repeated firings of the flash exceed the values shown in the table below, the 
flash firing restriction activates automatically to avoid degrading and damaging 
the flash head due to overheating. While flash firing is restricted, a warning icon 
is displayed to indicate the increase in temperature, and the recycling time is 
automatically set to an interval between approx. 8 and 20 sec.
When the internal temperature of the Speedlite increases, a warning 
icon is displayed in two levels. 
The following table shows the number of continuous flashes until the warning is 
displayed, and the necessary rest time until normal flash shooting can be performed.
* At full flash output with flash coverage of 14 mm/20 mm
* With external power source, the number of flashes will be two thirds (32 times or more)
Flash Firing Restriction due to Temperature Increase
Temperature Increase Warning
Level 1
(Recycling Time: 
Approx. 8 sec.)
Level 2
(Recycling Time: 
Approx. 20 sec.)
LCD panel illumination
Red (turned on) 
Red (blinking)
Number of Continuous Flashes and Rest Time
Number of Continuous 
Flashes Until Warning 
Display (Level 1) 
Necessary Rest Time 
Continuous flash (p.13)
48 times or more
10 min. or longer
Modeling flash (p.38)
The number of continuous flashes until warning display during 
stroboscopic flash varies depending on the flash output.
For the recommended number of flash firings, see the sections on continuous 
flashes (p.13), stroboscopic flashes (p.33) and modeling flashes (p.38).
If you change the batteries after firing many flashes continuously, be 
aware that the batteries might be hot. 
When C.Fn-20 is set to 0 (p.99), the warning beep does not sound even 
when flash firing is restricted.