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Lullaby.DK
Lullaby.DK
Lullaby.DK Tips and Tricks for the technical minded
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High speed photoHow to take photos like the one to the right.
It's a Tomato, being shot with a BB Soft air gun.
This guide describes how to capture super fast movements using ordinary camera gear, and a little home made electronics. I describe the different problems and how to fix them or work around them. Freezing fast motion, can give some pretty special photographic effects. Capturing a balloon just as it punctures. Or the impact of a pellet, just as it hits its target. Capturing such images introduces a lot of challenges. How does one handle timing with exposures times faster than 1/6000 second!? We have to handle shutter lag, synchronize the flash and time the exposure to just the right moment. But the shutter lag of any normal camera is so long that it will be all most impossible to time the exposures. And how do you synchronize the flash with an exposure time of less than 1/6000 second? To work around the problems with shutter lag and flash synchronization, the exposure is done in a completely dark room. This way the shutter can opened without actually getting an exposure. The exposure time set on the camera just has to be long enough for the action to happen while the shutter is still open. The exposure time set on the camera will not affect the exposure at all. To actually get an exposure, a flash is fired. The flash light duration will now become the actual exposure time. The output power of the flash, actually affects the duration of the light, so to get exposure times faster than 1/6000 seconds, the output needs to be reduced. For more information on the light duration please see Test: Sigma EF-500 flash. 
Now we only need to synchronize the flash with the action we want to capture. This can be done in several ways. For example synchronizing with a balloon puncture, can be done via sound. Impact-actions, like a BB Soft air gun pellets, can be trigged with a mechanical switch, like here to the left. When the pellet hits the the cd-cover it's pushed on to the switch, which then triggers the flash. My setup and work flow, for capturing a balloon puncture. The Gear:
First step is to set-up the scene. The black sheet is used as backdrop. The balloon, flash, microphone and camera are placed like in to image below 
Gear settings:
While trying to stay within the best performance on the lens, I either zoom or move the tripod, until I have the desired framing. Focus can be obtained either automatic or manual, but do remember to switch to manual, to lock focus. Otherwise the camera will try to focus when the lights are switched of. Now it's time to test the setup and lightning. All lights are switched of and the shutter is fully pressed on the camera. To fire the flash I just clap my hands. Then I review the image on the camera, checking for exposure, framing, focus and DOF. To get the correct amount of light / exposure, one can Increase or decrease: - the strobe distance to the balloon - the output power of the flash - the aperture on the camera - ISO sensitivity on the camera The test is repeated until satisfactory result have been reached, and the real photo can be taken. This is done the same way as when testing, but instead of clapping, the balloon is punctured with a needle. One could also just fill the balloon with water and shoot it with a BB Soft air gun :-)  - It's all up to your imagination.
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