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| In Deutsch |
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| In Deutsch |
Cave Photography
If you visit a cave, you might want to take a few pictures home.
Unfortnately 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 differenciate 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
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This is essential.
If your camera does not allow to turn the flash off, it is not sufficient for
cave photography.
- select color balance
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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 lightbulb.
As a result the pictures taken only with the light from lightbulbs 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
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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
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Okay, thats unnecessary for the picture, but it will be less annoying for the
other visitors in your group.
- use a tripod
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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
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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
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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
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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 impossibe to go
somewhere else.
It helps to have some friends firing additional flashes.
Obviously you need a tripod.
- Use Slaves
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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
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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.
See also
