what I was actually doing here was trying to maximize the height of the spout and increase the colliding drop size. I went to far and got more of a dribble for the second drop. I used a homemade piezo sensor to detect the first drop hitting the tank then varied the time till flash from there, I think these were like 200 milli second after first contact. The Camera axe makes this fairly easy and the piezo sensor makes it very repeatable. There is a lot of information on the Camera Axe forums. Oh and I was seeing about the same things as everyone else.