Nikon F4S - Rear-Curtain Sync Flash Photography

Rear-Curtain Sync Flash Photography
When using the Nikon SB-24, you can synchronize the flash to
the instant just before the rear (second) curtain starts moving.
Set the SB-24’s flash sync mode selector to “REAR.” This lets
you turn available light into a stream of light that follows the
flash illuminated subject. Rear-curtain sync flash photography
is especially effective at slower shutter speeds.
In Ph, P or A mode, shutter will operate as slowly as 30
seconds, depending on the background brightness.
84
Rear-curtain sync
Front-curtain sync