Nikon Camera N90 - Manual (Page 193)

TO CREATE NATURAL-LOOKING STREAM OF LIGHT—REAR-CURTAIN SYNC
Normally in flash synchronization, the Speedlight fires at the
beginning of the exposure. When the shutter speed is low, the
result is an unnatural light pattern.
When Rear-Curtain Sync is set, the Speedlight fires at the end
of the exposure, turning available light into a stream of light that
follows the flash-illuminated moving subject.
Since Rear-Curtain Sync Is especially effective at a slow shutter
speed. Slow Sync is automatically set at the same time that
Rear-Curtain Sync is set in the Auto-Multi Program or Aperture-
Priority Auto exposure mode. However, to set a desired shutter
speed, set the N90 to Shutter-Priority Auto or Manual exposure
mode.
• When the SB-25 or SB-24 is used, note that the Rear-Curtain
Sync setting on the camera body is ignored. So you have to
set the speedlight unit itself for Rear-Curtain Sync .
• Rear-Curtain Sync cannot be set with Vari-Program
• Rear-Curtain Sync cannot be set if Red-Eye Reduction (p.
144) has been set.
Rear-Curtain Sync with low shutter speed
Front-Curtain Sync with low shutter speed
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