Canon Speedlite 600EX-RT Mode D'emploi page 36

?: Stroboscopic Flash
Calculating the Shutter Speed
In stroboscopic flash, to ensure that the shutter stays open until the end
of the continuous flashes, set the camera with a shutter speed
calculated with the following equation.
Number of flashes ÷ flash frequency = shutter speed
For example, if the number of flashes is set to 10 (times) and flash
frequency to 5 (Hz), set the shutter speed to 2 sec. or longer.
To avoid degrading and damaging the flash head due to overheating, do
not shoot repeatedly with stroboscopic flash more than 10 times. After
shooting 10 times, allow a rest time of at least 15 min.
If you shoot repeatedly more than 10 times, the safety function may
activate and restrict the flash firing. If this happens, allow a rest time of at
least 15 min.
Stroboscopic flash is most effective when combining a highly reflective
subject with a dark background.
Using a tripod, remote switch and external power source is
recommended.
Stroboscopic flash is not possible with 1/1 power or 1/2 power flash.
Stroboscopic flash is also possible when the camera's shooting mode is
set to "buLb".
When the number of flashes is displayed as "---", flashes are fired
continuously until the shutter closes or the charge runs out. The
maximum number of continuous flashes is shown in the table on the
following page.
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