Over a year ago now I constructed a sound activated flash trigger and had some success using it to capture water balloon bursts. The circuit has been dug out, but this time I had help in the form of more flashes and manpower!

Exposure: 2s  Aperture: f/5.6  ISO: 400  Focal Length: 55 mm

I was tempted to start this post with “An engineer, a designer and an IT guy walked into a garage…”. But since I could not think of a good punch line I will just say that the IT guy bamboozled the designer with techno-babble, causing him to fart incessantly to the detriment of all concerned. Perhaps a curry dinner to start the evening in a garage was not a great idea for Sven, Chris and I….

Anyway, having learned lessons from my first attempt we decided to hang the balloon rather than hold it to remove hands from the image – a long needle tipped poking device was fashioned. Secondly, we placed the sound trigger higher than the balloon since water on the mic drum was the reason my last attempt was cut short. We first started with a balloon completely filled with water – however this proved unsuccessful since it made little to no noise and therefore did not activate our ring of 4 flashes.

Exposure: 2s  Aperture: f/5.0  ISO: 200  Focal Length: 105 mm

So air was added to the top of the balloons and we had some good success. Keep in mind the shutter speed values in the shots are meaningless since the flashes really determine the length of the exposure. With all the flashes set to the lowest power they are able to achieve a “virtual” shutter speed of approximately 1/30000 of a second – far quicker than our cameras are capable of.

Some of the flashes were gelled (blue clearly visible in the top shot) with two behind and two in front. We had two cameras covering the action. One telephoto from a distance level with the balloon and the other closer, wider and shot from above.

Exposure: 2s  Aperture: f/5.6  ISO: 400  Focal Length: 55 mm

So after mastering the hanging balloon we decided to add a human element in the form of faces and hands. I really like the way the hand crushing the balloon looks.

Exposure: 2s  Aperture: f/5.6  ISO: 400  Focal Length: 52 mm

Another lesson learned is that a very violent pop produces the best results I think. This was achieved by using more air in the top and pricking the balloon with force. Occasionally we would get a double image, either from a second sound (echo) firing the trigger twice or the general crappiness of our Chinese radio triggers putting the flashes slightly out of sync. A debounce circuit could be added to the trigger to counter the former.

Exposure: 2s  Aperture: f/4.0  ISO: 200  Focal Length: 108 mm

So I think it was a great change from our usual (of late) driving mindlessly looking for subjects. I think there is plenty of scope for improving the sensitivity of the trigger and trying other (booming voice) “Photos at High Speed!”.


12 Responses to “More Adventures at High Speed”

  1. Jon on April 21st, 2009 11:55 am

    Goto say, love those top two. So violent looking.

  2. Sven on April 21st, 2009 12:04 pm

    I actually like the third better than the second- the flare from the side adds something, I think. I didn’t think so at the time, though.

  3. Jon on April 21st, 2009 12:09 pm

    It does add a nice highlight. It is just not as violent looking which is what I liked – the spray around the bottom etc. You can see from the photo that the blue one had a lot more air in it.

  4. Sven on April 21st, 2009 12:32 pm

    It is quite violent, true. Maybe next time we can pop them by just inflating the things until they burst 🙂

  5. Jon on April 21st, 2009 12:34 pm

    Yeah! El-cheapo Super Cheap air compressor!

  6. Jon on April 21st, 2009 5:39 pm


    Streamers coming out of a party popper?

    Popping the balloon from underneath using a tack in the palm of hand so that the resultant water sphere looks to be resting on hand.

    If only BB guns were not illegal in our nanny state.

  7. Sven on April 21st, 2009 8:05 pm

    Guy suggested hundreds and thousands. He also suggested honey, though.

  8. Sven on April 21st, 2009 10:58 pm

    According to the official documentation:

    SB600 at 1/64 power: 1/25,000 sec
    SB900 at 1/128 power: 1/38,500 sec
    430EX: “1.4ms or shorter” Yay, Canon specs 😛

  9. Jon on April 21st, 2009 10:59 pm

    Excellent ideas! Tell him we will do it at his house next week!

  10. Jon on April 21st, 2009 11:00 pm

    I checked and Canon’s have been measured at 1/30000 for 1/64 and 1/36000 for 1/128 (which the 430EX does not have).

  11. Sven on April 22nd, 2009 3:20 pm

    So, with wired flash to sync things properly, we should be able to achieve 1/25,000 with the four flashes. Excellent!

  12. Jon on April 22nd, 2009 3:36 pm

    Yes. It seems the radio triggers can have a *maximum* response time of around 1/1000 which would have been the reason for our double images.

    Wiring the flashes will not lead to any greater freezing of the action but will stop double images and therefore give a sharper image.

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