If you want take a photo without see the iPhone, the biggest problem is with the button of the Photocamera App and risk of moving too much but P@parazzi will solve for you the problem.
It's really simple! Double tap on the screen allows you to take a photo.
Photos will be taken after 2 seconds, time for autofocus; then the picture will be saved in the photo library, and the app will vibrate for alert you.
It's possibile activate the flash with a swipe up and off swipe down.