Slow Sync Flash
Combining flash with a shutter speed long enough for ambient light to register, so a sharp subject sits within a blurred environment.
Measured in
seconds
In depth
Ordinary flash exposure kills the ambient and leaves a black background; slow sync balances the two, so the flash freezes the subject while the longer shutter records the surroundings and any movement as blur. Combined with rear-curtain timing, the resulting trails follow the subject naturally.
Examples in practice
A dancer lit by flash at 1/8 s appears frozen while coloured stage lights streak around them.