Camera Axe is open hardware (based on Arduino) and open software project that helps you get some of those difficult to capture photographs. It can use various sensors like light triggers and sound triggers to activate a camera or a flash.
Check out my blog (Hobby Robotics » Camera Axe)post for more details.
Here are a few sample images I captured with it.
The second image is amazing. Great work
Great work!
Darn, now I'll have to add an external flash to my 'must buy soon' list ! 
Ver
Great shots 
I am building a lightning detector for photography.
You can an add it as a sensor for a trigger.
the source is here Lightning Detectors
That lightning detector looks like a fun project. One question about the design: given the huge tolerances on ceramic disc caps, does it make sense to replace the one in the tank circuit with a trimmer?
What's the timing of the output pulses like, relative to lightning strikes? Does it detect the "build-up" of potential energy, so the pulse leads the strike? Or is it detecting a product of the ionization, so the pulse lags? That would make a big difference in how it could be used for shutter control.
Ran
I'm just curious how the lightning detector works. Does the radio detector pick up something in advance of the bolt?
From wikipidia: Lightning - Wikipedia -- a bolt of lightening lasts about 30 microseconds. There is no way the camera is going to capture an exposure in that interval.
Lightening ... talk about a misspelling; especially that medical definition...
Before the Camera Axe I did a separate project on photographing lightning. This post has many more details about how the lightning detector I used works. My method just detects light and it works fine. According to research I've done (details in the link below) you have about 100ms which is enough time for a DSLR camera. Note this is a different (and I believe simpler) lightning detector than Shutter mentioned. Another advantage of my method is you can use it through the camera's viewfinder to make it directional where as Shutters would be omnidirectional. I admit it's a nifty idea, but I'd like to hear if there are any practical advantages to the method mentioned by Shutter.
