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David shows you how to capture Peeps exploding... -
It's 3 a.m. and a phone rings in the White House...Or actually, it was about 3 p.m. and a phone rang in my pocket. By chance the phone happened to be mine and on the other end of it was 3ric asking if I'd be able to help with a project that evening. Seems he had acquired about 10 liters of liquid nitrogen and, among other things, was hoping to use it to do some high-speed flash photography of frozen things shattering into a million pieces upon being shot with a pellet rifle.
All was well and good according to plan, except for the flash trigger, which was stuck in the mail somewhere. Could I hack one together by evening? And thus is how I got my project for the day.
A flash trigger for high-speed photography is a really simple device. Basically all you need to do is take an audio signal and use that to trigger a flash if the signal exceeds a certain level. Rather than muck about with $10 worth of op-amps, transistors, voltage dividers and a bunch of so-called "electrical engineering", I splurged for the $2 solution and threw the equivalent of a mid-1980's personal computer at it... i.e. a microcontroller. Specifically, an AVR-based Arduino board. (ok, so the arduino cost me $30, nitpicker).
Long story short and after overcoming two rather significant obstacles (#1 being not having a microphone, #2 being not having a flash) we were able to kludge together a workable flash trigger. By the end of the evening, with me manning the trigger and fellow HBL'er David behind the camera, we got some cool pics.
Related:
High-Speed Photography Kit. Capture high-speed events -- A splash. Popping balloons. Breaking glass. Use your imagination! Adjustable flash controller triggered by light or sound.
Homemade Strobe Photography & read more in the MAKE digital edition.
