Nikon D300 User Manual page 350

This special
Aperture-priority auto
since the camera controls the shutter speed in those two
settings. Primarily, you'll use this setting when you are
shooting in Manual
a known X-Sync speed.
My Recommendation: I leave my camera set to
(Auto FP) as shown in
works just like it normally would until one of my settings
takes it above 1/250s shutter speed, at which time it starts
pulsing the light to match the shutter curtain travel. Once
again, you won't be able to detect this high-frequency strobe
effect since it happens so fast it seems like a single burst of
light.
Just remember that the flash loses significant power (or reach)
at higher shutter speeds since it is forced to work so hard. Be
sure you experiment with this to get the best results. You can
use a big aperture like f/1.8 to have very shallow depth of
field in direct bright sunlight since you can use very high
shutter speeds. This will allow you to make images that many
others simply cannot create. Learn to balance the flash and
ambient light in
technical talk will make sense when you see the results. Pretty
cool stuff!
Which Flash Units for Auto FP High-Speed Sync Mode?
If you are using the camera's built-in pop-up Speedlight, or
the small Nikon SB-400, your camera's maximum flash
shutter speed is limited to 1/320 s. If you use the external
Speedlights SB-900, SB-800, SB-600, or SB-R200, you
X-Sync mode
(A) or Programmed auto
or in Shutter-priority auto
Figure 4-48, all the time. The camera
Auto FP high-speed sync mode. All this
350
is not available
(P) modes
and want to use
in
1/320 s