Freeze Time with High Speed Photography
Written by: Tiffany Joyce
Someone recently forwarded me an e-mail which had some fantastic pictures. One of those pictures was of a balloon popping. The photo had been timed such as to capture the burst just at the right moment. I then realised that it is impossible to manually time a shot with such accuracy. I was also reminded of a picture I had seen in my 12th grade physics book of an exploding banana which had been captured using a capacitor. A little research and I found that it is pretty simple to take a picture of an exploding fruit (or anything that you would like to explode!) or a popping balloon. This post will give you a good idea of what is known as High Speed Photography.
Surprisingly, many people are under the impression that all such images are taken simply using a very high shutter speed, really good timing, and plenty of shots. But in this episode of Mythbusters we bust that myth. In actuality, these images are shot using a flash triggered at just the right moment, and to make sure that it gets triggered at the right moment, we use sound triggers or light triggers. So it is not the shutter speed that decides the exposure here, but the flash speed, which can vary from 1/1000th of a second to a few hundred nanoseconds!
Photo by Praveen M Tomy
Sound triggers obviously use a loud sound to trigger the flash (like the firing of a pellet gun). Light triggers on the other hand use an invisible beam of light (infra-red mostly) which when cut, triggers the flash. Water droplets are often shot using light triggers You can either purchase a fully functional model or a DIY kit which is pretty easy to set up and costs much less. You can get them online from sites like www.hiviz.com or http://www.makezine.com/flashkit/.
Without any further delay, the essentials for the act are:
- An external flash (because you won’t be able to trigger the on-camera flash as and when you want)
- A trigger for the flash (this could be a sound or light trigger since manual triggering won’t work)
- A very dark setup wherein the only light reaching the sensor should be the flash (that’s the whole point)
Triggers are often coupled with delay circuits which allow you to adjust the delay between the trigger getting activated and the flash firing. Experiment with the delay for an interesting variation in results. And you can see an example of a High speed photography setup here.
The best thing about high speed photography is that you keep looking for new stuff to try. Bust an egg, pop a balloon, shoot a fruit… the list just goes on! How about an exploding light bulb?! Go ahead, give it a shot and put up a link. We’d love to see!
(Thanks to my friend Abby for helping with the pics!)
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