I just can guess... have only a hero available and lens looks little different to hero 2 and complete different now with gopro3. Find the real lens under the glass "roof". and than turn the cam away from you so you can see the glass "roof" from bottom to top. in my case I would try it as marked in second screenshot.
Last edited by gkaefer on Thu Jan 10, 2013 2:50 am, edited 1 time in total.