The High Speed Photography technique enables the perfect capture of tiny moments of time. The exact moment a glass shatters, the moment of impact as a bullet smashes into an apple, the perfect corona from a splash of liquid to name a few examples. The two problems that come with this technique are 1) creating a shutter speed fast enough to capture the moment with complete sharpness (i.e. no motion blur) and ensuring there is enough light for the exposure 2) getting the timing perfect for moments that last only a split second.
First of all we have to understand what a ‘fast’ shutter speed is – commonly used shutter speeds are between 1/60th sec – 1/2000th sec depending on circumstances. Maximum shutter speed on modern DSLRs (i.e. the briefest time the shutter is open) is 1/8000th sec. Which sounds pretty quick doesn’t it? Until it’s revealed that the effective shutter speed used for the above image is around 1/23,000th sec. That’s quick! To be fair 1/8000th sec is still fairly rapid and on a very bright sunny day you could capture some fairly impressive frozen movement. However the weather is not always a photographer’s friend and even at its best is still unpredictable. So we head back into the controllable environment of the studio. Here we can also control more the quality and direction of the light so we can add to the aesthetic of the images.
To learn more about how a shutter works and what governs conventional shutter speed check out this video by the Slo Mo Guys.
In the studio the only viable lighting solution is using some kind of strobe set up. This gives us more challenges – when working with any strobes we have to make sure that the shutters in our cameras open in time with the flash going off. That is why each camera has a maximum recommended ‘sync speed’. If you exceed this shutter speed (usually around 1/200th sec on a DSLR) you will catch the shutter blades in your image and will get dark banding across your images. However no matter how much light we can pump out of our strobes, we will never be able to get close to the shutter speeds required. So we have to do some lateral thinking. If we can’t achieve a fast enough shutter speed literally, we have to approach it another way. In a perfectly dark environment the ‘effective’ shutter speed can be achieved using the flash itself. The flash becomes the shutter speed. Imagine in a dark environment, before and after a flash going off there is no light and therefore no image is imprinted on our camera sensors outside the flash duration. If you set your camera on a long exposure (seconds rather than split seconds) press the shutter and trigger the flash whilst the shutter is still open then the camera will record the image and the shutter speed will be the equivalent of the flash duration. Whatever the flash duration e.g. 1/2000th or 1/8000th or 1/23,000th of a second then that is the effective shutter speed you will get. There are no ‘flash duration’ settings to be found on strobe lights but we can govern the duration by adjusting the power setting. Unfortunately this does not work on most studio flash set ups because of the way that the power is generated in these strobes. Specs on most of the best known brands show that the shortest flash duration tends to be between 1/2000th-1/4000th sec. I found that this was not quite quick enough for this application. The good news is that this technique works very well with Speedlites. The way they are designed, the lower the power setting, the shorter the flash duration. After a bit of research I discovered that my Yongnuo 565 at 1/128th power (the lowest setting) would create a flash duration of just 1/23,000th sec. Now we’re talking!
So that’s the shutter speed issue dealt with – how do we get our timing to work so that we capture the moment of impact?
Well at this stage we need another piece of kit – a sound trigger. It’s quite simple really, it’s an electronic device connected to a microphone and with a cable that links to the speedlite. When the microphone detects a noise it sends a signal through the box to the speedlite and triggers the flash. Therefore the flash fires as the action climaxes e.g. the blade hits the apple and the noise is made. Your camera already has it’s shutter open either on the B setting with a cable release or a long exposure on the self timer to capture the image. And that essentially is how it’s done. Of course there is fine tuning to be done with positioning of the microphone and there are controls for sensitivity etc. It requires experimentation and practice but the results as I hope you can see can be rather spectacular.
If you do decide to have a go yourself it can not be overstated how important it is to be safety minded. Please do not do anything that will endanger yourself or anybody else. Even though some of my images may look as if they might have been a bit risky I used a lot of jiggery-pokery to ensure that my model and I were never in any danger whatsoever.
Of course if you want to learn to use this technique with me in a safe and controlled environment then have a look below at the two High Speed Photo Workshops I have planned for you.