In this tutorial from the Intermediate Flash Photography course, you'll learn about a really cool photography technique called stroboscopic photography.
We're going to be using a slower shutter speed, and instead of worrying about whether the flash is going to fire at the beginning or at the end of the exposure, we're going to fire the flash many times during the exposure.
Here's an example of what this looks like in a photo.
I don't know about you, but I think that's pretty cool. Stroboscopic flash is not always available on all flash units, but it's pretty common on Nikon and Canon speedlights, so you can check your user manual to see if your flash will do it.
How to Create Stroboscopic Flash Photography
The first thing that you need to determine is how long the action that you want to capture will take. In the above example, I determined that it would take about 1 second for me to run across the frame of the camera.
The next thing you want to do is set your aperture and ISO so that your long shutter speed leaves you with a very dark or even completely black image. Because of this, it's pretty much imperative that you set up your shot in a really dark area without any ambient light.
For example, here's a shot where I set up with some ambient light present.
As you can see, there's some ghosting going on, and you can actually see through the subject. I think it's a pretty cool look, so it's something you can play with—but let's try to get it right first, and then we'll break some rules.
Another reason that a really dark area is important is that you want to be able to have an ISO and aperture setting that allows you to use a relatively low flash power. The reason you want to use a low flash power is that you're going to be firing your flash many, many times in fast succession, and you don't want to put too much strain on your flash or the batteries. I recommend trying to stay below 1/32nd power, or if you can, even less than that.
So once you've determined what your flash power should be to properly light your subject and not blow up your flash, you need to determine how many times you want the flash to fire during your exposure.
The way you do this is by setting your flash mode to Multi on Canon or RPT on Nikon. This gives you a setting for hertz, which is a measurement of how many times per second the flash will fire.
If you want your flash to fire 10 times during a 1-second exposure, you'll set it to 10 Hertz. Of course, if you had a 2-second exposure and you wanted to fire 10 times, you would set it to 5 Hertz, which would be 5 flashes per second times 2, equalling 10 flashes.
You can adjust the setting up or down until you get just the feel that you're looking for. A lot of times it'll take experimentation to see exactly how it all fits together.
The final setting you have in stroboscopic flash is the total number of times the flash will fire. You can use this setting if you don't want the flash to fire all the way through the long shutter. If you leave this setting blank, the flash will fire as long as the shutter is open or until the flash runs out of batteries or gets overheated.
Stroboscopic Flash Photography: Examples
Let me show you how this all comes together with some photos. In this first image, the shutter speed was 1 second and the flash was set at 7 Hertz.
It looks as if I started the exposure a little bit too early, so the first two flashes happened before I came into the view of the camera. So as you can see, timing is key in this kind of photography.
On a second try, the timing was a bit better, and we can see all of the seven flashes going off within the camera frame.
It looks much better, and you get a pretty good sense of the motion that's going on, but it still looks a little disjointed, and I think we can do better. By turning up the frequency, we can get a more densely packed image, since the flash will go off with less time between the flashes.
Here's what 12 Hertz looks like with a 1 second exposure:
I think this is really cool, and you can get an even better feel for the motion in this image. I like it so much that I tried another one with me jumping.
That should get you started on the basics of stroboscopic flash. If this is something that interests you, you should do a lot of experimentation and play with it. There's probably an entire course worth of material just on stroboscopic flash. In fact, if you want some great inspiration, look up the photography of Dr. Harold Edgerton. I especially like the stuff he did with baton twirlers.
So your homework for today's lesson, if you're interested in the stroboscopic flash, is to play with the Multi setting on your flash. You can grab a friend and go outside and get some running and jumping shots like I did, or it can be as simple as setting up in your house with a bouncing ball. Make sure to have some fun and experiment!