The Triggertrap Sound Sensor & High speed photography

The sound sensors in the Triggertrap are sensitive, and absolutely ridiculously fast. How fast? Fast enough to take a photo of a balloon based on the sound the balloon makes when it pops? Let’s find out…

I promised that I would post some pictures and videos from the testing process, but so far, I haven’t really delivered on that promise. Most of the testing has been pretty boring, to be honest (testing whether I can take 100 photos consistently isn’t my idea of an interesting video or article… But it turns out I can, as I showed you in the Timelapse video demo). When I saw the results of the balloon test, however, I was hella excited.

Let’s not beat about the bush, here’s the video with the results:

[youtube=http://www.youtube.com/watch?v=Gba1M7Fz_Fg&w=600&h=407]

How is it done?

The reason why I am triggering flashes instead of the camera is that quite simply; the camera doesn’t react quickly enough to the signal from the Triggertrap. Flashes, however, are as instantaneous as it gets, so I used a 3.5mm cable and the 3.5mm socket to dual flash hotshoe adapter (It’s available in the Triggertrap shop, all the way at the bottom of the page, under “Other Accessories”) to connect a couple of flashes to the Triggertrap instead.

Since I have no way of triggering both the camera and the flashes, I’m instead setting the shutter manually. In these photos, the camera is set to 1/3 of a second shutter speed, and a relatively small aperture. By taking the photos in a relatively dark space and by using a bright flash, you ensure that the photos come out well: The Triggertrap registers the sound, and triggers the flash, which, in turn, is used to ‘freeze’ the motion in the shot.

At first, I tried to use a single flash set to 1/4 power, but I got a bit of motion blur in my shot:

The reason for this is because of the way flashes work: They don’t actually flash brighter or less bright depending on their flash output. Instead, they modulate their duration. So: At full power, the flash is a lot longer than at low power.

So, for my next experiment, I used the same single flash, but set to 1/64 instead. Here, I had to move the flash closer to the balloon, and adjust the aperture on the camera to match the flash output. The result was pretty decent:

Then, suddenly, I remembered that the device I was using to trigger the flashes was a dual hot-shoe adapter. I have plenty of Canon Speedlite 580 EX II’s, so I figured I may as well add another flash. By triggering both the flashes at the same time, I had twice the amount of power, and that, in turn, meant that I could reduce the flash output from both flashes to 1/128 instead. Two flashes with 1/128 is (in theory) the same amount of light as one firing at 1/64 – but with half the flash duration. Perfect.

The photo taken with the twin flash setup is the one you’re seeing in the final shot in the video:

(The reason for the slight ‘ghosting’ in this image – i.e. the outline of the balloon before it popped – is that we had the lights on for this shot so we could film the video. If you darken the room further, there won’t be any ghosting)

Programming in a delay

Finally, if you want to use a slight delay before triggering the shutters or the flashes, the Triggertrap has a delay feature built in, so you can choose the number of milliseconds you want to delay your shot. Perfect if you, for example, want to take a photo of a rifle bullet, but you know that there’s going to be a slight delay between the sound of the gun and the bullet flying by.

The Triggertrap: Coming soon!

Sound awesome? Damn right it does. And the Triggertraps are going into production very soon indeed, so if you ordered one via Kickstarter, it’s time to start getting excited. And if you didn’t, well, it’s not too late…

Check out Triggertrap on Facebook, and keep an eye on the Triggertrap group on Flickr as well, for more sample photos taken with the TT!