FujiFilm EF-X500 Owner's Manual page 18

Adjusting Settings
FP mode (high-speed fl ash sync)
At high shutter speeds, the fi rst and second curtains in the cam-
era's focal-plane shutter pass over the sensor simultaneously with
a small time gap, exposing only a narrow slit, with the result that
the light from a normally-timed fl ash reaches only a small section of
the sensor. Flash photography consequently requires slower shutter
speeds, severely limiting the range of speeds available. The EF-X500
supports FP (high-speed sync), in which the fl ash fi res continuously
while the fi rst and second curtains travel across the sensor, allowing
the fl ash to be used at any shutter speed.
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