Cave Photography

If you visit a cave, you might want to take a few pictures home. Unfortunately this is rather difficult, at least if you want good pictures. It is essential to have the necessary equipment. Fortunately modern digital cameras are getting continually better and so even simple cameras are sufficient, if some tricks are used. It is important to differentiate between show caves with electric light and unlit caves.

Caves With Light

The essential idea about taking pictures of show caves is to use the existing light, this is called available light photography. The lamps are placed for good effect, so half the work is already done. This has another important advantage, the humidity in the air will not reflect the flashlight and there will be no ghosts.

turn off the built in flash
This is essential. If your camera does not allow to turn the flash off, it is not sufficient for cave photography.
select color balance
Caves lit with electric light generally use light bulbs. Modern cameras have an option for the color temperature of the picture, which can be turned to light bulb. As a result the pictures taken only with the light from light bulbs have normal colours. Without this, the pictures would be brown or reddish. Some cameras allow to specify the color temperature in Kelvin, as rules of thumb light bulbs are around 2,700°K and fluorescent lamps (like modern energy saver lamps) are between 3,500°K and 5,500°K. You can also try automatic colour balance.
turn up film speed
Actually there is no film, so film speed is replaced by the sensitivity of the sensor to light. Most camera allow to increase this value. The drawback are small red dots, noise which is also increased with the sensitivity. You should check your handbook or simply make a few test pictures to determine whch value you can safely use without getting visible noise. Be aware: the highest vaue available will definitely produce noise.
turn off sounds
Okay, that's unnecessary for the picture, but it will be less annoying for the other visitors in your group.
use a tripod
If you hold the camera in your hand it will tremble, which will result in blurred pictures. Yes, we know, its strange to carry a tripod through a cave, and most likely it is not allowed. But there are several alternatives, the easiest is to use the handrails. Unfortunately other visitors may use them for what they are intended to, and they will tremble, making good pictures impossible. Then it is better to use a rock, a wall, a column. Please avoid to use any speleothem. A good alternative is a mini tripod which you can press against your chest to reduce trembling. And it help to hold your breath while taking the picture.
select underexposure
The cave has bright spots where the lamps are and dark regions where no lamps are. If you do nothing the resulting picture will be bright but also blurred. By reducing the brightness of the picture, say by two full steps, the pictures will be dark with the area around the lamps normal. Thats what one expects from cave pictures, and it is easier to brighten the picture afterwards than to darken it. If the picture is too bright the lamps and their surrounding is just a white area without any structure.

Caves Without Light

The essential thing with photography in dark caves is obviously the lack of light. As a result there will be no light for the auto focus and no light for the picture. It is easy to understand, that this will require some equipment.

Second Camera for Closeups
If you have a cheap digital camera with built in flash, this is ideal for taking closeups. All it requires is the possibility to start the autofocus manually before taking the picture. Just use your torch to light the scene for the autofocus, then turn off the lamp and press the shutter button.
Select Bulb Shutter Speed
Bulb opens the shutter, so you have time to send a few flashes, then close the shutter with a second press. The cave is totally dark, so you have as much time as you want to fire the flashes. Unfortunately you do not see anything without light so it is impossible to go somewhere else. It helps to have some friends firing additional flashes. Obviously you need a tripod.
Use Slaves
Slaves are flashes which have a sensor. When another flash is fired, this slave will fire too. The idea is to place several flashes at various locations, then take a picture with the built in flash, which triggers the others.
Use Computer Flashes
A computer flash has a light sensor built in. It is adjusted to a certain aperture, time and film speed, then it fires exactly the right amount of light.