Monday, January 18, 2010

Sound Triggers

As a kid,
I loved pictures of things that happened too fast for the human eye to see. The beating of a hummingbirds wings frozen in time or the classic bullet slicing through a playing card photo always fascinated me.

When I started looking around...
at how to make such images, I found enough information to build something called a "sound trigger" This is a little electronic circuit that can fire a camera flash in a dark room when triggered by a sharp sound. Snap your fingers and the flash fires. Pretty neat!

Building the kit was fairly straight forward, but hooking it to the flash was not. I jury-rigged a hot shoe, of sorts, with some aluminum and speaker wire. It was crude, but it worked.

Now for the set up:
In order for this to work, you need a dark room and a remote shutter release. I set up in the garage with my camera on a tripod pointed at a board about 3 feet away. The camera was set to a 3-second exposure at f/4.5 and ISO 200 (manual focus of course). I turned off the lights and made my way back to the board where the camera was aiming using a flashlight. Here's the sequence of events:

  1. Grab an object to be broken (a CD, a light bulb etc...)
  2. Turn off the flashlight
  3. Remote trigger the shutter
  4. Break the object
  5. Wait for the shutter to close
  6. See what you got!
  7. Repeat

Because the flash...
fires so fast (about 1/10,000 of a second!) and the room is dark, the camera's sensor is able to capture the action at that speed. Its a pretty simple concept that can work with any camera with manual mode and a remote trigger.

It took a while to catch the action at just the right moment to make an interesting photo. To adjust when the flash fires, I needed to move the sound trigger either closer or farther from the breaking object. Sound take time to travel.

Another issue...
is that sometimes the falling pieces are loud enough to re-trip the flash and give you a double exposure. I found I had to time it so the shutter would close right after the object broke.

In the end I learned a great deal about this type of photography *and* got some pretty good images too! These are among my most popular on Flickr.

Give it a try! You might find its like being a kid again!

Further reading:

Sound Triggers
Flickr High Speed Group
Some Awesome Shots

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