This shot is an attempt to show the control that can be achieved with manual off camera flash.
To get this look I needed to bring the ambient exposure, including the bulb, right down low with a combination of exposure time and aperture. Now, as I want to light my arm using the flash, I'd rather get the exposure time down low so I don't have to use a tiny aperture and nuke my arm with full power flash. Using a flash, the fastest exposure I can get is limited by the sync speed of the camera. This is quoted as 1/250s for the D50, but, as this fine piece of machinery has an electronic shutter, we can work
a bit quicker than that, even with a wireless flash trigger slowing things down. Having set this down to 1/320s (I have got faster than 1/500s on other occasions), I stopped down the aperture to get the bulb looking right then bumped the flash up to give the correct exposure on my arm.