Sometimes it’s amazing how slow our sense of time is. We find [Maurice’s] bullet capture system a great example of this. A pair of IR sensors spaced two inches apart can capture and calculate the speed of a projectile. Couple this with a user-input distance from the sensor to the target and a microcontroller can extrapolate the exact moment to trigger a camera to catch a bullet in mid-air.
As with his other projects, all the details on how to build and use this system are available for your perusal.