Next, we will calibrate the timings to capture droplet collisions. We will determine the Flash Delay first. Set "Drop1 Size" to 10ms and "Drop2 Size" to 0, so that only one drop will be released. The flash should be triggered when the first drop rebounds from the water and goes up to its highest position. Click the auto-calibrate button to the right of the Flash Delay setting. Set "Step" to 5ms and "Interval" to 5s, then click the Start Calibration button. Pluto Trigger will now take a photo every 5 seconds and increase the Flash Delay by 5ms each time. Monitor the screen of your camera. When the droplet reaches its highest point, stop the calibration.