To exceed your camera’s maximum flash sync speed (which is something around 1/200th – 1/250th second), you need high speed flash (Auto FP flash, in Nikon terminology) where the flash pulses at ca. 40kHz instead of firing all at once.

You need an external flash for this, like an SB900 or a 580 EX.

• When you need it: when you need to exceed your flash sync speed, e.g. when taking an outdoors picture of close object with blurry background. That means low F-number, which means even at 100 ISO you’ll need fast shutter speeds.
• Advantage: in theory, you can you can go to any fast shutter speed and still use flash.
• Drawback: you lose much power, so that Fast Flash is usually only suitable for close-by subjects.

The Shot: Shoot a close object or person with blurry background. To achieve this, set your camera to A/Av mode, and select a wide open aperture (f/2.8,say). (If your lens cannot go down to f/2.8 or it is a very dull day, you may need to go to 400 ISO).

You should now be exceeding your flash synch speed-if you set your flash to Fast Flash. Else you get an overexposed picture (your camera will refuse to go faster).

Note, your object has to be close, especially if you get to speeds of 1/1000th o rfaster. Else, your flash will not have enough power.

And now you can get this – the following image was lit by flash at 1/1600th second, at f.2.8!