I had a slave built for my F4 but it does not seem to like working on the D70s

http://www.lightningtrigger.com/
Electronic Features:
Extremely sensitive optical flash sensor responds to lightning flashes at distances up to 20 miles (day) and 40 miles (night), flash strobes and infrared (remote control) transmitters
Automatic light level sensing daylight to dark - no manual adjustments
Automatic metering system activation available for many cameras to ensure proper exposure and minimum shutter lag time