Help camera locks

[fried chicken]

sometimes when i'm using the camera, it locks in place -- and i can't take photos
(a little lock icon appears on the screen)
i can't figure out a way to unlock the camera, thus i have to restart the phone

can anybody help me out?

 

[W_A_Watson_II]

To pressed the power button. Press it again to un-lock. I accidentally do it a lot as well, aggravating isn't it.