EXIF: Canon EOS 60D, Lens: EF-S15-85mm f/3.5-5.6 IS USM, Focal length: 19mm, 8.0 sec (however actual exposure by an external flash), f/6.3, ISO 160.
Canon Speedlite 430 EX II, with blue gel, fired in manual mode at 1/32 power.
This photograph has been shot by using an Arduino based trigger for my speedlite. A piezo sensor was placed under the water glass. Once the ice cubes splashed the water, the piezo sensor provided an input to the Arduino board, which in turn fired the flash.
The camera was set for 8 seconds duration, in a pitch dark room. Needless to say, the camera shutter is opened up before dropping the ice cubes. Care must be taken to avoid any stray light from entering the frame.
The water glass was placed on a table about 2 feet high, and about 4 feet away from a white wall (background). The external speedlite was placed, facing the wall, on the floor about one foot in front of the camera. The speedlite was set manually at 1/32 of its full power, in order to minimize exposure time. Also, the speedlite was manually zoomed to 105mm setting in order to concentrate the beam and thereby bring in some vignette effect. The speedlite was covered with blue gel (Okay!… I’ll admit…those were in fact wrappers from Quality Street candies)
I assembled my own Arduino based trigger largely with the help of internet forums and a few friends, with total cost being less than about USD 20. If anyone is interested in knowing further details, please drop in a comment and I’d be happy to help.