Ok, I am surprised about the long exposure time, I usually use about 1/200th of a second to avoid motion blurr, but seeing you use such a long time, I will try this too on my next droplet session
The time machine times everything. Flash lag, intervals between drops, if you set it for two drops..And with the flashes I have you can set them to 1/128th power, which gives a quick burst of light needed to freeze action with (no blur), in the shot.. The shutter speed has to be about 1/4 to 1/2 second and the room is kind of dim.. If the shutter speed is to short the picture just comes out black...