Many thanks to Guy Montag for making this video that shows how to make a contact trigger for a flash, although I expect you could also use it to fire a camera if you wire it up to a Pocket Wizard or similar.

Here's the YouTube version of the video, or there's a better quality version. If you try this for a shot involving high-speed capture then remember to keep your flash power as low as possible. The lower the flash power is, the shorter the flash duration will be, so you can freeze the action better to get a sharper image.

 

[youtube]http://www.youtube.com/watch?v=GVUxKnNMW44[/youtube]

 

ps. Just in case you don't know, the way to use a contact trigger is to work in the dark, leave the camera's shutter open, and then do whatever you're going to do to trip the trigger. For instance if you were going to shoot an air pistol through a balloon then this is how you'd go about it:

  1. Set-up the balloon and pre-aim the air pistol with it mounted on something so it won't move.
  2. Position the contact trigger to the side of the balloon opposite the air pistol, so the pellet will pierce the balloon and then pierce the trigger.
  3. Put a thick block of wood behind the contact trigger to catch the pellet. Make sure animals and kids are locked out of the room.
  4. Turn off the lights.
  5. Open the camera's shutter.
  6. Fire the pistol. While the shutter is still open the pellet will burst the balloon and then pierece the contact trigger, which will fire the flash.
  7. Close the camera's shutter.

And that's pretty much all there is to it. But exploding balloons have been done a million times so try to think of something new.