The moment of the trigger pull, which starts a rapid series of events that result in the shotgun's blast. This 12 gauge semiautomatic shotgun uses the gases of the blast to cycle the gun, expelling the spent shell and loading the next. The shutter speed was set at 1/6400th of a second and captured what I had been observing through the lens throughout the morning. I saw the flash of flame but it took quite a few frames to reveal what you see in the final image.