Canon SPEEDLITE EL-1 Advanced User's Manual page 80

How to Determine the Shutter Speed
To ensure that the shutter stays open until the end of the continuous flashes for
stroboscopic flash, 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.
Caution
To avoid degrading and damaging the flash head due to overheating, set repeated
shooting with stroboscopic flash to 30 times or less. After shooting 30 times, allow
a rest time of at least 10 min.
If you shoot repeatedly more than 30 times, the safety function will activate and
flash firing restriction will be carried out. If this happens, allow a rest time of at least
50 min.
Note
When performing stroboscopic flash, combining a highly reflective subject with a
dark background is most effective.
We recommend using a tripod and a remote switch.
Neither 1/1 power nor 1/2 power flash can be set.
You can also perform stroboscopic flash even 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
Continuous Flashes
High-speed sync (
)> (bulb shooting).
is shown in the table on the next page.
) cannot be set during stroboscopic flash.
Maximum Number of
80