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.