This photography project was done in collaboration with a friend: Baptiste Jayet.
This is a series of pictures of droplets falling in water; we captured the moment of impact. The scene is illuminated from behind; a coloured plastic sheets is placed in front of the flash. The pictures are taken with a low angle relative to the water surface in order to obtain a sharp contrast for the ripples.
We encountered two technical challenges during this project:
- We had to make sure the exposure duration was short enough for the droplets to appear frozen in time. The camera used did not allow such a setting. We decided to let the camera expose for a full second in a dark room. The flash was set to a duration of a few milliseconds; this is what allowed short exposure.
We needed to trigger the flash exactly when the droplet touched the water surface. This part was more tricky: we ended up building a small detection setup.
- using a syringe we could create droplets in a reliable and consistant manner
- a laser pointer was shined horizontally towards a photo-diode
- when the droplet is falling, it momentarily interrupts the path of the laser light which no longer shines on the photo-diode
- using an arduino, the photo-diode output is measured. When this output signal falls a trigger signal is sent to the flash and the picture is taken
- By hocking up a variable resistor to the arduino we were able to tune the delay between the detection and the trigger.