Underground Photography like any kind of photography, is curious blend of art and science. Both are essential and the absence of either will result in a poor product. The science part is having a true insight into the relationship between light levels, space and time. With this understanding comes the ability to program your camera for optimum pictures.
Lets start with the concept of exposure. This has two elements. Light Level and Time.
Simply put, a Low Light Level + Long Time = High Light Level + Short Time.
The quantities available of both of these elements are determined by the equipment at the photographer disposal. I think it is fair to say that usually there is only a finite & small amount of light available underground, but this can be compensated for by increasing the time element of the equation.
Another governing factor is the ISO number. This should be set as low as possible. But remember, the lower the ISO, the more exposure will be required. A low ISO accompanied with more exposure will always give the best results. Low ISO numbers are great for small passages, but become less useful with larger areas. Unless a greater amount of light can be called upon to illuminate a larger area, the ISO will have to be raised. This, in effect makes the camera more light sensitive, but the price that has to be paid for this is a deterioration in picture quality. Very large ISO numbers for example 400 will introduce unwanted elements into the photograph in the form of graininess and colour deformation.
So the science aspect has the following elements that must be balanced and assessed:
Light Level
Exposure Time
ISO Number
Area To Be Photographed.
Lets consider the last item on the list. I like to think of the first three items as the photographer weapons with which to tame the area to be photographed. The larger the area, the harder this is to accomplish. What must be grasped is the fact that the quantity of exposure (Light + Time) required to photograph increasingly larger chambers is not linear. If chamber 1 required “X” amount of exposure and chamber 2 is twice as large as chamber 1, then it will not require twice as “X” to photograph, but more like 4 times as much. This is the major contributing factor that makes big chamber shots so difficult. With the biggest chambers, simply getting enough exposure can be a tour de force.
(Tip) I should mention that whilst exposing a larger area, the foreground will almost certainly acquire enough exposure from the incidental light used to illuminate the background. To directly illuminate the foreground, even for a very short time, risks over-exposing the foreground.
And now we come to the artistic side of Underground Photography. This is what will have the biggest impact on the quality of your photographs. Let us consider a basic passage shot. It is too easy to simply set up the tripod and expect to see in the photograph something similar to what the eye sees. This will not work/. With a little time and thought it is always possible to improve on the first “Impulsive Shot”. Consider the height of the camera, would it be better lower down ? This can sometimes produce a dramatic effect. How about angling the camera so that one wall of the passage takes up more of the photo? this is nearly always more pleasing to the eye than the 50/50 approach.
Framing the shot is something that must be perfect. Without this basic element the photo will be sub-standard. Look carefully at the four corners of your camera screen. It is sometimes too easy to forget those whilst concentrating on the main elements of the photo. The corners (and the four sides) will sometimes contain intrusive elements that would ruin an otherwise good photo. Its difficult to advise on this aspect of picture composition, but what I can say is – Always try to give more. Think about a photo before you shoot it. Think about how it could be improved. If you are not sure.. then take multiple shots.
Often an underground picture can look confusing where there is nothing to indicate the scale. This is where it is sometimes useful to have someone pose for you. Without a person, a photograph of a dramatic underground scene can look curiously bland when you view it later on the PC screen.
Lastly, don’t be over critical of your photos. I have come to learn that different people have widely different viewpoints when it comes to assessing Underground Photographs.
Nimrod.
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