camera object exposure

I've added a camera object using this code:

var cam: Camera = Camera.getCamera("1");

cam.setMode(1024, 768, 24);

var video: Video = new Video(1024, 768);

video.attachCamera(cam);

video.x = 0;

addChildAt(video, 0);

but it doesn't auto expose well like the native camera app does - so if i hold an led light near my face the native camera app adjust exposure accoridngly whereas in my air app it stays massively overexposed - any way to resolve this?