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Rangefinder
Magazine First Exposure: by John Rettie
High-speed photography has always been a dedicated field of photography that needs specialized equipment such as extremely high-speed movie film cameras and/or high-speed powerful flash systems. Students of photographic history will know that Harold Edgerton, the inventor of the strobe light, took amazing pictures of bullets in flight using a strobe light of incredibly short duration. How many photographers have wished they had the equipment to at least try to do this sort of photography once, if not for a paying job, but just for the challenge? Now thanks to a machine, appropriately called the Mumford Time Machine, any photographer can capture these hard to obtain images relatively easily using everyday photo equipment. Bryan Mumford is an inveterate inventor who originally developed the Time Machine in order to accurately time the swing of a pendulum in a grandfather clock. He then realized that thetimer would be a great photographic tool.
The Mumford Time Machine is a small electronic timer that is capable of timing events to an accuracy of one millionth of a second. It is hooked up to a camera so that it can trip the shutter or trigger a flashgun at exactly the right moment using sensors. These sensors activate the Time Machine using sound, touch, vibration or the breaking of a light beam. For example, in order to photograph a pellet at the exact moment it enters a light bulb, the Time Machine can fire flash guns after a special ballistic sensor actually measures the speed of a pellet by timing the length of time it takes to pass between two sensors set four inches apart. The Time Machine is then programmed to fire the flash at the exact moment the pellet passes a spot, by measuring the distance from the sensor to the spot where the pellet will hit the object being photographed. The accuracy is within one quarter of an inch, once everything is set correctly. In order to capture shots such as a balloon popping, the image has to be captured by a flashgun fired not only at the correct moment but also for a short duration of 1/4000 of a second or faster. Otherwise, the image will be badly blurred. Surprisingly, this can be achieved easily on most flashguns by setting the power to 1/8 or less. In case you don’t know the duration of your flash system the photodiode detector sensor can be used by the Time Machine to measure the exact length of a flash exposure, so that one knows ahead of time whether the flash will be fast enough to capture high speed action. For example, I set my Vivitar 285 flashgun on its 1/8 power setting and the Time Machine indicated the flash duration was 1/4000 of a second.
After I had confirmed that the Vivitar flash was just about fast enough, my first test was to photograph a balloon popping. It was a three-person task and my two sons were more than willing to help in such an experiment. One held the sound sensor about a foot away from a balloon held by my other son. I put the camera on a tripod and handheld the flash connected to the Time Machine. In a darkened room I set the Nikon D1 camera on a four-second exposure and pushed the shutter button. My son popped the balloon with a pin and the sound captured by the sensor activated the Time Machine, which in turn instantly fired the flashgun. A quick check of the image captured showed the balloon just as it was about to collapse from popping. It was a reasonable first attempt at high-speed photography but the lighting was not as good as it might have been and the balloon was slightly blurred. The lighting for the next shot we tried was better but the sensor was held a few inches further away form the balloon, which had completely collapsed by the time the flash fired. However, the exercise confirmed how accurate the Time Machine is at firing the flashgun and how critical the timing is for getting good high-speed photographs. This is pretty amazing when you consider it only takes .000443 seconds for sound to travel six inches! Have you ever wanted to be able to capture a shot of a bird the instant it lands on a feeder? Even better, have you ever dreamed of emulating those great slow- motion films showing the beautiful patterns created by drops of milk falling into a bowl of milk? These shots have all been done using high-speed cameras in the past or have required the patience of a wildlife photographer waiting hours in a blind for the right moment to capture a bird or animal. With the Mumford Time Machine you can just set up a sensor, leave the camera and flash plugged in and walk away. The Time Machine will do the rest unattended.
A bird landing on a feeder can be captured by using a sound trigger or a motion detector. Capturing drops of milk is a little more complicated. Basically, a photo interrupter sensor is set up below a drip feeder. Each time a drop of milk falls through the sensor it sends a signal to the Time Machine. It then fires the flash to capture the milk drop in motion. The trick is to set the Time Machine to fire the flash after the first drop has passed the sensor. Then each successive shot is captured just a little later to make a sequence of images each one millisecond apart. Obviously the drops will be falling faster than the camera and flash can be readied for the next shot. That’s no problem for the Time Machine, as it can be programmed to have a “time-out” period for a set number of seconds between each shot. If the shots are captured on a digital camera it’s then possible to put the sequence together using a program such as Imageready (Photoshop’s companion program) to make a short QuickTime video. All of this might be fun but the Mumford Time Machine has other modes that can be useful to the professional photographer. For example, it can be configured to fire an electronic flash as a slave to the built-in flash in a camera and can even be configured to ignore the pre-flash of digital cameras or the multiple flashes of red-eye reduction systems. One very useful feature of the Time Machine is the ability to accurately measure the shutter speed of film cameras by measuring the duration of time that light passes through the lens when the shutter is tripped. Furthermore, it can measure the lag time between when the camera shutter is tripped and when a picture is taken, and as mentioned before, it can measure the duration of an electronic flash in millionths of a second. It can even measure the lag time between when an electronic flash is triggered and when the light actually appears, again in millionths of a second. Time-lapse photography is another feature supported by the Time Machine. It can be set to take images at predetermined times. This can be done by setting gaps of time, such as a shot taken once every 30 minutes or a mode called “Timed Shoot,” which allows one to set a clock and then specify up to 100 different times of day to take a picture. This is useful for photographers shooting a construction project for example, where a picture needs to be taken every day at say 9 a.m., 11 a.m., 1 p.m., 3 p.m. and 5 p.m. It could also have security value, if one needed to capture a picture at certain times of day. The Time Machine costs $295. The numerous sensors required for tripping the unit cost anywhere from $35 for a simple sound or motion detector to $125 for a laser sensor. An ordinary PC cable is used to trigger a flashgun. In order to trip a camera shutter Mumford supplies an infrared emitter for use on most Olympus digital cameras and a serial interface cable for other digital cameras such as a Nikon Coolpix. Mumford can modify remote shutter release cables as used with many cameras. Be sure to check out Mumford’s web site for numerous examples of images captured using the Time Machine. It’s quite an inspiration. It might motivate you to go out and try capturing elusive wildlife or even a dynamic shot of a popping balloon. John Rettie is a photojournalist who resides in Santa Barbara, CA. Readers can contact him by e-mail at john@johnrettie.com or by snail-mail in care of Rangefinder. Further Information
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