I made this video to demonstrate the stopping power of speedlights. I used 3 speedlights so I wouldn’t need to use any one at full power. The flash duration is slowest at full power. I used speedlights by 3 different companies; Canon, LumoPro, and Yongnuo. There fall-off times varied slightly, but at 1/4 power on each, the duration for all 3 was slightly faster than 1/2000th. That’s fast enough to stop most movement, but the tiny birds visiting my bird feeder were unbelievably quick. I can’t say I got super-sharp freeze-frame, but I did get pretty darn close. Watch the video to see how I did it.