Most of the case for underground photography there are no direct light source are available, so for the first consideration should be given to use the best equipment rather than a traditional camera with its own built-in flash, for this situation it is preferable for the flash to be detached from the camera and in place a tripod and flash bulbs 0r electronic flash is to be used with the same position each time. You can even use 8 to 10 bulbs for one shot. Alternatively also you can use a portable flash unit with detachable head like the Metz CT 45 that can be good for light source but it may be necessary to take few supplement of the internal batteries especially if you have planned to take a large number of photographs per session. A large Ni-Cad pack or a sealed lead acid battery is suitable.

Also for better result a 35mm camera with a B or T setting on the shutter is desirable especially, which allows a high quality of enlargement. Also consider to use a wide-angle lens that can give large angle of view even which can work in narrow passage and capture the photograph from greater coverage.

To avoid over exposing in fairly narrow passages use a medium speed film (100 ASA). Take utmost care when you are increasing the size of the aperture especially if it is sole source of illumination as if you are increasing the size it will lead to over-exposure. To illuminate further down the passage best to fire the flash taking considerable distance from the camera. The next step is to learn the technique of “picture building” and accurate colors to achieve at the printing stage though it depends on certain amount of luck for the end results.