I wanted to do some high speed macro photography and read online I could do it with an external flash and a trigger, so I tried it out and it was quite easy. Here is how I did it.
How it Works:
In a completely dark room, open up the aperture on your camera and leave it open. The camera wont be able to record anything as its completely dark. Fire a flash unit at a certain time and anything illuminated during the flash’s duration will be recorded on the camera. The trick is to have whatever you want captured triggering the flash somehow so it fires at the right time. Trying to do this manually wouldn’t really work. In my case I built myself a laser tripwire circuit, and a sound activated switch. this is how it works:
1. Open the camera aperture, generally I use a 5 exposure time, use a low ISO (100-200) Aperture F 11-16 and if possible use manual focus, although it has worked without it. If your doing macro it will need to be manual focus.
2. do the ‘triggering action’, in most of the example shots, the action was dropping something onto a hard surface, this could also be firing a bb gun, popping a balloon etc
3. the sound activated switch picks up the noise and triggers the relay
4. the flash fires
5. whatever is illuminated while the flash is on (which is fast) the camera will capture it.
I have put it all into a 40L plastic box so that I can explode some glass light bulbs without making a big mess. I used a sheet of glass I had around to protect the camera, the sound activated switch is inside a little plastic box with the microphone on the hard surface (a brick)
Some of the shots I have gotten so far using a glass surface and dropping ice cubes (click for big)