How to fake it in high speed photography

December 07, 2012  •  Leave a Comment

I'm a big fan of high speed photography that freezes motion and reveals things that you just can't see in real time. So naturally, I would want to create some of my own. The standard approach is simply cranking up your shutter to the shortest interval possible, in my case 1/4000s. There are a couple of problems with this approach:
 

  1. You need a lot of light to do this. Think noon on a cloudless day at the beach, and sometimes that isn't enough.
  2. Attempting to recreate the brightness of the sun indoors is prone to undesirable outcomes, such as incineration.

As an example of this approach, here are a couple pictures of news helicopters hovering near my house when there was a nearby brush fire:

The frozen rotors are nice, but as it was a slightly overcast day when I took these, the light is a little boring and both of these images would need considerable work to make them presentable.

So what's the alternative? Fake it with a flash. Even though most cameras cannot use a flash at faster than 1/250s without resorting to some kind of trickery (that usually involves expensive equipment), this is really all you need to freeze action under more controlled conditions that do not involve helicopters. The secret is in the duration of the flash. Most flashes fire a burst of light that only lasts between 1/1000s and 1/30000s. So, if you arrange things such that the flash is the only source of light in your picture, the duration of the flash burst then becomes your effective shutter speed.

To accomplish this you need a camera that works in manual mode (sorry, smartphone users). First, you need to disable any setting that automatically increases your ISO, and set your ISO to the lowest value allowable - in my case this value is 200. Check your camera manual for how to do this on your equipment. Second, set your shutter speed to the highest speed that will still work with a flash - in my case 1/200s. Now, start taking test shots without the flash, and close your aperture (set it to a higher number) until you get a completely black picture. Now you know that the flash is supplying all the light for the picture. You will want to stop at the lowest number that gives you a black picture, as this will allow the flash to work at a lower power setting and provide a shorter burst of light. The flash that I am using has a duration of 1/1000s at full power, but only 1/20000s at minimum power. This can make a big difference depending on how fast your subject is moving.

After that, turn on the flash and start snapping. Taking advantage of light falloff (which I will not be covering today), I was able to turn my kitchen into a black backdrop for this:

20120225_102320
1/200, f/9, ISO 200, flash fired remotely from camera left at 1/16 power

Don't be afraid to experiment. Here's another one that I took when I was supposed to be washing the dishes:

a_billion_little_bubbles_by_speedofmyshutter-d5nbtgk
1/200, f/7.1, ISO 200, flash on camera in auto (TTL) mode.

I really like that I was able to see that the stream of water from my faucet is actually made up of bubbles, and that the water does not travel in a straight line but looks more like a snake. Both things I couldn't see just by looking.

Have fun with your new technique, and please comment with links to your own creations!


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