“Cine Meter is a professional film/video/photo application for your iPhone®, iPad®, or iPod touch®, using the built-in camera to provide a shutter-priority reflected light meter, an RGB waveform monitor, and a false-color picture mode. Cine Meter works on any iDevice with a camera running iOS 5.0 or higher.”
-http://www.adamwilt.com/cinemeter/index.html