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There are two common ways to 'stop motion' in a high-speed photograph: the first is to use a lot of light, your fastest shutter speed with the aperture wide open on a fast lens, and lots of trial-and-error. Getting this kind of shot is mostly a matter of luck. The second way is to use our Flash Controller, your slowest shutter speed with the aperture wide open, and a darkened room. The darkened room insures that the only light going into your camera comes from the high-speed flash. With a fast enough flash (or strobe), motion is stopped although the shutter speed setting on your camera might be a few seconds long. It seems wrong at first - using a slow shutter speed to take a high-speed photograph. 
Since the Flash Controller has adjustable delay, you can 'tune in' the time between the sound and the flash. For example, if you are taking a picture of a balloon popping, you can 'tune in' a big hole in the balloon or a small one. It usually takes about 3 tries to get the balloon hole size just right. You may never see a balloon in mid-pop using the fast shutter speed method because you would have to be very lucky to time it right - one thousandth of a second error in timing makes a difference. Basic Features of the Flash Controller The Flash Controller will trigger a flash or a strobe at just the right moment. The right moment is usually determined by a sound. The included microphone senses a sound, and the flash controller provides a signal to the flash. There is a gain knob, which changes the sensitivity of the microphone: at low gain, it takes a loud sound to fire the flash. At high gain, a soft sound will trigger the flash. The flash controller also has a delay knob, which adjusts the time delay between the sound and the flash. The Flash Controller can also trigger on changes in light intensity, using the built-in photo sensor. The usual way to use this feature is to interrupt a laser pointer beam that is pointed at the photo sensor. The gain knob and delay knob work the same for both the microphone and the photo sensor. The photo sensor is automatically active when the microphone is unplugged. Power up the Flash Controller by plugging in one of the output cables (2.5mm for the flash, 1/4" for the strobe.) The Flash Controller takes a standard 9V battery, which can be accessed by sliding the panel that is on the bottom of the Flash Controller. Make sure to observe the plus and minus signs which are embossed at the bottom of the battery compartment. We Don't Want to Touch Your Camera! The Flash Controller attaches to a Flash (or a Strobe). It does not attach to your camera. The sequence for taking a picture is as follows:
Here is another advantage of this approach: by not attaching our product to your camera, there is no way we can break your camera. Some of our customers have really expensive cameras. High Speed Photography has a Long History Harold 'Doc' Edgerton did the pioneering work in the 1930's. He took the first pictures of bullets going through apples, bullets going through playing cards, balloons in mid-break, and so forth. But Edgerton had to use film. With digital cameras, it is easier to instantly evaluate your results, so 'tuning in' the timing is much easier. That is why we decided to offer the Flash Controller - now anyone can try it. Edgerton's work is on exhibit in Nebraska and also at MIT. New Features for the Photographer Most of the ideas for new features in the Flash Controller Version 4 come from our customers. You can see many examples of our customers' fine work at Flickr.com: search for the MAKE: Strobe Photography group or the High Speed Photography group. 
For taking pictures of water drops, you need extra high gain. This is because a drop of water doesn't make much noise as it lands in a pan of water. You can remove a jumper on the circuit board for extra high gain. For taking pictures of breaking balloons, a 0-11 millisecond delay range is ideal. This is the standard setting for the Flash Controller Version 4. For taking pictures of falling things, sometimes this isn't enough delay time. Removing a jumper on the circuit board changes the delay range to extra long delay: 0-500 milliseconds (half a second). For most high-speed photographs, you only want to capture one instant in time. This means that the Flash Controller Version 4 must trigger the flash once for each photo. For pictures of high-speed sports photography, sometimes multiple flashes are the answer. Removing a jumper on the circuit board changes the 'blanking interval' from the normal 3 seconds blanking interval to no blanking interval: about 2 thousandths of a second. The setting of no blanking interval means that the flash will fire every time the sound is loud enough. You can use your own SnapShot II "DJ/disco strobe" instead of using the build-your-own flash included with the Flash Controller Version 4. The SnapShot II is a faster, brighter strobe, and costs only about $60US. The SnapShot II is daisy-chainable, and you can use up to 4 SnapShot II strobes by removing a jumper from the circuit board. Each SnapShot II will also need a 1/4" mono guitar cable.
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