camTrigger

camTrigger lets you take high speed photographs at the very moment of action, with just your iPhone!
In this app, shutter is triggered at the sound level predefined by the user. So if, for example, you are taking photograph of a bursting balloon, shutter is triggered at the sound of balloon burst. This lets you capture the exact moment of action.
Such sound triggered photographs earlier required buying separate sound triggers and cumbersome flash setups in dark rooms etc. Thanks to iPhone's incredibly fast camera and camTriggers innovative inbuilt sound trigger, you can now achieve this with only your iPhone, and in broad day light.
camTrigger also lets you setup very high shutter speeds for the photograph. As long as you have enough light in the scene, you can setup shutter speeds faster than 1/50,000th of a second.
camTrigger provides full creative control on your photograph. Such as manual focus, EV, resolution, shutter speed etc. camTrigger has an inbuilt sound meter, to monitor and set the sound trigger levels considering the background noise and the sound of action.
Free version of camTrigger is fully functional and has all the features. A one time in-app purchase will let you take photographs without watermark on photos.