by GroundquestMSA » Jul 14, 2013 8:12 pm
First of all, I have to say that I'm NOT a good photographer. I know only a few basics that allow me to at least get a "legible" photo. As rlboyce said, don't use the flash on your camera. If the passage is small, or not too foggy, you can light it up with a few headlamps and get a well lit photo. Have your buddies help you light the shot and try not to allow any light source to shine from directly beside the shutter. If you have a big passage or lots of fog to deal with, you can "lightpaint," meaning that you put the camera on a tripod or set it on a ledge or so on, and take a long exposure shot while evenly "painting" the scene with your headlamp(s). Your Lumix camera doesn't allow you to manually set a specific exposure length, but it probably has a fireworks scene mode, which will give you an exposure of up to 8 seconds.
More advanced methods call for additional off camera flashes, but I know nothing about that.
Have fun!