Sekonic SPEEDMASTER L-858D Operating Manual page 92

4.
Touch the radio button of the Number of Pre-flash Button.
Set the number of pre-flash on the Number of Pre-flash Screen.
The display returns to the Measuring Screen.
If you do not change this number, touch the [Close] Button to return to the Measuring
Screen.
NOTE
The amount of pre-flashes fired by a flash unit can be different for different camera brands.
Check the camera manual for number fired by your camera system.
Number of Pre-flash Screen
78
5. Measuring
[Close] Button