Multiple Flash Exposures - Nikon Autofocus Speedlight SB-22 Instruction Manual

MULTIPLE FLASH EXPOSURES

To create multiple-exposure "stroboscopic" effects or
paint the scene with light, use the following procedure:
1. Disconnect the flash unit from the camera body.
2. Set the camera at B (bulb).
3. Push the open-flash button repeatedly—as many
times as desired.