This project shows how to build a sensor to trigger a camera’s flash using a microphone or laser pointer. The brain of the project is an Arduino and it will activate the flash at accurate timing to capture precise moments. You can easily add new sensors, or even run multiple sensors at once. Since the triggering of the flash is done in software it’s easy to add delays, or make a more complicated triggering algorithm based on multiple sensors.
Triggering a Camera’s Flash with Sound and Light – [Link]