Techniques.

there are three main techniques in general use by underground photographers:

1.        Manuel set-up

2.        lightpainting/open shutter

3.        slave flash based

manual set-up is simply setting up your camera on tripod and setting it for a timed exposure  like 30 secs or setting to open shutter and one or more people Manuel firing flashes in a given location, the disadvantage here is everyone has to turn there lights out just before the shot and stay very still when the shutter  is open to avoid blurring, when used well this technique is as good as any but the people involved need to be aware of the problems of movement blur etc. rather than just a casual hold flash, fire, move on. good as a fallback set-up when other thing dont work its also a good place to start as it requires no slave units etc.[a typical image/url]

the second, lightpainting is fare more artistic in nature as you can "paint" in shadows, highlight points and regulate exposure very simply, light painting can be dun with any strong light source but remember the colour of the light will effect the white balance of the shot, halogens like searchlights give yellowlight, led headlights bluish white etc. but flashes are still often best as the light is a good neutral shade, so what do you need to set  up a lightpainting shot? the first essential is a tripod as a solid base for a successful lightpaint shot is number one priority as  the shutter will be open for up to several minutes at a time, the second is a good  idea of how you what the picture to look, this is where the creative stuff comes in and you can simply experiment if you have time or as i do, look at the way peoples headlights light the subject from different angles and replicate the best of these with the flash's or lights, the actual painting is best dun in one of two ways.

1.        with one person behind the camera to open the shutter and providing enough light that the photographer can walk though the shot  and fire of several flashes out of shot and or paint the scene from a one or more positions without actually appearing in frame (a lot of care has to be taken here a avoid your shadow being in shot even if your not!)

2.        you can simply paint the whole scene from behind the camera position, this is a simpler way but can often produce a rather bland, flat result, the best time to use this method of open shutter photography is for situations where getting fare into the shot with flashes etc. is difficult or impossible such as looking out from a ledge into a passage or large chamber, its also good for simple recording shots for industrial archaeology in mines, quarries and the like, here often a simple well light shot is the order of the day rather than a more artistic approach.

the third type and most widely used type of UG photography is slave flash, this is a very versatile method of lighting and can be as simple as a single flash unit with a slave fitted held by the photographer and triggered by the on camera flash (whether built in or if your using an SLR hot-shoe mounted) or as complex as multiple slave units spread over a wide area or along a passage using a ladder effect to trigger the units where the  nearest to the photographer is triggered from the camera flash and the next nearest slave from that one and so on, creating a chain of light that overall will light areas beyond the trigger range of the original unit.

There are several types of slave trigger unit:

1.        the cheapest and most easily available are ambient light slaves these work on picking up any strong light source as a trigger, the problem with these is that they are easily set off by a stray headlight and are of quite limited range, they are however  perfectly useable and as they are very cheap and readily bout in any camera shop are good as a back up to other types and i usually carry a couple as spares

2.        infra-red slaves are in my opinion the best,  they are not too expensive, effective over quite a long range (up to 20M in a strait line) and need very little light to trigger but as they work on a different frequency they are usually not triggered by headlights. the only commercially available infrared unit is the firefly from [firefly electronics/url] these units are based on a design by mike Gibson and a cheaper kit version plus other useful electronic bits for the UG photographer are available from [his site/url] the firefly 3 in also available albeit at well over twice the price of a standard unit, this is a programmable slave for digital compact cameras that have a preflash, the problem with these is at around £60 a pop they are hardly a throwaway item and if like me you use multiple units it can get very expensive plus the fact that underground they will eventually sarcom to the wet or dirt get into the circuitry etc, so if you have a good compact will works well overall underground but has a pre-flash it maybe worth considering but this will limit you right at the start, as you could soon find yourself spending more on slaves as you expand than your camera's worth !

      3.   the third type is wireless also known as radio slaves, these i have little personal experience with though they             are seemingly the favoured try used by studio photographers and in film however taking photos                               underground is an entirely different game and for me infrared in the form of firefly 2. units with a backup of             one or two ambient slaves works well and doesn't overcomplicate the matter, from talking to fellow UG                     photographers i understand that the main problem with these slaves is that there range is limited by direct             visible area so they do not work well in winding passages and amongst large areas of boulders or                             breakdown piles unless carefully placed.

                                                                                  .........on to next page> Shot set-up