You can use the iPhone 4's HDR (High Dynamic Range) capability to take pictures under sub-par conditions (too much or too little light). When you turn HDR on, your iPhone will take three pictures in quick succession with different exposures and then blend them together to produce the best image. Here's how to use it:
- Open the Camera app.
- Tap on HDR at the top center of the screen to turn it on (tap again to turn it off).
- Tap on the bottom-center camera icon to take a picture.