Okay the image below left is an HDR image of this skateboarders hangout taken during the day. Gives an idea of the hangout as it is. Its situated in Pittenweem, Fife, Scotland. At night its pitch dark. I ventured down there with my camera, tripod & torches.
Its 1 long exposure, shutter speed 2 minutes. Using a very small aperture. I set the camera up in front of the hangout. Clicked the remote then guided the torch slowly round the outlines of the wall art. Each outline was done twice to allow enough luminosity. The torch was held as close to the wall art as possible.
Focal length 20mm
Manual Bulb mode
Shutter speed 2 minutes