Actually, for the shot I just posted I did not need to take too many shots. When you get to this speed the shutter is not enough to freeze the action. You need to freeze it with flash. I set my flash manually to 1/128th. I use Yongnuo 565EX flashes. I have a 580EX II and 580EX as well but the 580EX does not have a miniport and the one on my 580EX II no longer works. I find it pitiful that I find my Chinese knockoff flashes more reliable than the real things.
To fire the camera and flash at the right moment I use two Stopshots from Cognisys. Even with this there is a tremendous amount of work to do. Everything takes time to setup and then I spend a lot of time trying different things to get what I am aiming for.
In this particular case I started with the column. Once I understood the # of milliseconds at which the drop hits a particular point and I know at what time the water column reaches the point I want, I know how many milliseconds I have to collide another drop with the top. I then fired another drop from a different siphon at a few milliseconds after the drop the forms the umbrella. This was the tricky part as originally my goal was to have this drop fall through the umbrella. I played with the timing a bit to get this happen and then noticed it wasn't as interesting as I thought so I then strove to get the drop just above, which proved a bit challenging. Ironically I kept getting the drop falling through the umbrella - which I was trying to do before but now didn't want.
I really enjoy water drop shots and I am slowly learning different tricks. It's not easy to take these shots but it is very rewarding when you get a good one.