As I wanted to capture events very close to when they happen (like the popping of a balloon) I decided to use a BB gun. This way the sound that trigger the flash will happen “long before” the bullet hits the target and I can alter the delay (or move the microphone) to get the picture at the time I want.
This was the first try and adding more delay would give a nicer result.
As a side note; shooting indoors, in the dark, is very dangerous and requires a lot of preparation. A modern BB gun is very powerful and goes through a water filled balloon with high velocity. It may also change trajectory. I was fortunate to set this up correctly because my older son was skeptic to my initial bullet capture. It turned out he was right and I am grateful.
One of the things I wanted to test was the famous balloon shot. To take a picture exactly when the balloon raptures. This turned out to be a bit more complex than I had thought. One thing was simply the physics involved. Although I am an engineer at hart I had never really read up on balloons and what made them pop. It turns out that the big sound bang does not come from the air rushing out of the balloon but rather from the latex accelerating and passing the speed of sound barrier. The problem for me was that using the sound from the popping balloon to trigger the flash leaves very little time.
After having seen so many great photos of what I later learned was high speed photography I wanted to make some myself. I had so many ideas but all of my first experiments failed due either the delay of the shutter release (the time it takes for the camera to actually take the picture) or the limits of the flash synch.
Once I had understood the basic concepts; the fact that the extremely short exposures are not made using the camera but rather the burn time of the flash I started to look for hardware solutions to solve my needs. There were a couple of nice products available but I thought it should be possible to make one cheaper myself and then I could also modify it to my needs.
Velleman is a company that develops small circuit boards for home assembly and they have a product called MK139 – it is a clap on/off switch that you can use to control lights etc. After assembly it turned out that the delay after a clap until the relay closed the circuit was not useful.
The project grew and I replaced the PIC processor that came with the kit with a PIC12F683 and wrote some code to make it work. Once this was done I wanted to be able to control the time between the “clap” and when the flash fired so I added a trim-resistor and modified the code for it. If you want to do this yourself I put the code on https://github.com/reveman/mk139_and_PIC12F683.
If you think the picture looks a bit complicated (messy?) it is because I added some extra connectors to be able to change power, flash connector and microphone/accelerator. These are not required.
Welcome to my little blog. Although some other things may sneak in the major focus will be on photography.
Although I link in pictures here my main gallery is at http://reveman.smugmug.com