Is there a way on the 5D2 to have a shutter press start and exposure then a second shutter press stop the exposure. I am trying to do some long exposure light painting where I will not be at the camera and will be triggering the camera with a set of pocket wizards. This is traditionally called T Mode I believe but not available on the 5D2 stock firmware. I have not been able to find an option for the at in the latest nightly build of ML and haven't found an answer when searching the forums.