[VikingPhotography]

Brian,

The answer here, of course, is to use an external lightmeter and set your camera's exposure and flash power output levels manually. There is no pre-flash from either built in or hotshoe mounted strobes when they're triggered in this way.

Pre-flash is required for all TTL metering modes that you camera might use, whether that be programme auto, shutter priority or aperture priority (or any variations thereof)

In the days of film SLR's, there was still a pre-flash required if you set P, A or S modes - the camera had to know exactly what shutter speed and aperture was required and this was the only way of doing so when in auto or part-auto modes. The only difference with film cameras - particularly Nikon - was that they calculated the flash output duration by taking a reading off the film whilst it was being exposed.