Putting it all Together

Lighting principles
While we want some shadowing to provide a sense of depth, we don’t want large, harsh shadows. A classic way to shoot a scene with two flashes is to have each at about 45-degrees to the camera. Each produces shadows, but harsh shadows tend to be canceled out. Often one uses a powerful main or “key” flash, and a second, weaker one to reduce the harshness of the shadows. Backlighting (aiming the flash directly towards the camera) produces very dramatic effects, bringing out wall features such as scallops quite well. Many cave formations are translucent, and backlighting can be used to emphasize this, as in the photos of the bacon on pages 38.
Flash placed underwater (pages x,y,z) can emphasize the blue-green nature of cave water. Otherwise, water often acts as a “light sponge,” because it often absorbs rather than reflects light, and can look very dark in relation to the rest of the scene.
Show Cave:
Unless you are photographing a particularly attractive cave formation, usually as a close-up, most cave photos tend to be more interesting with people in them. They give a sense of scale to the image, and if in motion, a sense of something happening in the image. If on a tour, typically I use one external flash with a synch cord that I can hold, and if someone is on the tour with me, they can hold a second external flash with a slave. Good pictures can be taken fairly quickly this way, but keep in mind that other people’s flashes will also trigger your slave.
Undeveloped caves
Without the constraints of a tour, you have much more flexibility when shooting in undeveloped caves. Indeed, the chief constraints are your equipment, the patience of those assisting you, and the need to protect the cave. The importance of the latter cannot be over emphasized. When shooting in delicate areas, utmost care must be taken not to damage the cave. Stepping on a bed of crystals or putting a muddy boot onto clean flowstone are never justified, no matter how important it is to get the flash in “just the right spot.” But there are many tricks that can be used, such as putting the flash on a monopod and holding it where you need it.
The ideal photo team has at least four people: one to act as a model, and two to man the flash units. The latter can help you compose your scene by shining their lights from the flash position. With fewer people, you can use tricks such as setting the extra flashes on rocks or ledges, or on tripods.
Remember to reward those who help you with copies of your best photos, since they have put in their time for YOUR photos.
Further reading
There is far too much to say about cave photography than can be said here. But there are two excellent books on the subject available through the National Speleological Society’s bookstore (www.caves.org). These are Images Below, by Chris Howes, and On Caves and Camera, published by the Society with contributions from many authors, including several chapters written by me.

From : Dave Bunnel