Tripod Mounted D700
Nikon 50mm 1.8 Lens
2 Second Exposure @ f/8
SB-600 in Umbrella, triggered with D700
Flash in TTL Mode with -0.7 EV
For this shot I set my D700 up inside the house, facing outward. I placed my Nikon SB-600 unit up inside the metal frame of a photographic umbrella.
I asked my wife to stand-in on a mark while I locked down the focus. After focusing on her face, I changed the camera to manual focus mode. From that point forward, as long as I stood on my mark, I was good-to-go with regard to focus.
The flash was set to TTL with a negative EV dialed in as to not overpower the shot with blown areas, and I began with the camera set to about 1/125th of a second. This produced some nice shots but the rain was frozen as round droplets and it didn't give the desired effect. So, I began to slow the shutter down to draw out the droplets into streaks as you see here.
Now, the flash is what freezes the action in this instance, and not the shutter. You might think that slowing the shutter speed down to 2 seconds wouldn't have an impact on the look of the photo because the flash should still do its thing for the fraction of a second it's firing. But the Nikon CLS was maintaining communication between the camera and the flash and when I slowed the shutter down on-camera, the camera then told the flash to extend accordingly, providing a longer period of time during which the drops could be seen.
I grabbed some glasses and a book from the shelf to add some weirdness, and to ensure that my wife called me a 'big dork,' and was good to go. In all, I think I took about 15 photos, with this being my favorite.