Read original post at Mayhem Software Blog
In late November / Early December I updated our application Camera Flashlight . The original version was turning on the camera flash (to be used as a flashlight) by causing the camera to continually auto-focus. The problem with this method is that it caused the flash to blink on an off momentarily once the camera had focused. Not ideal for a flashlight but it's an approach that almost all wp7 flashlight apps seem to use.
Since then I worked out how to keep the flash on via accessing the video recorder which is much more desirable because it results in a constant stream of light without blinking. It also puts less stress on the phone's camera.