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Most people do not live near a coastal site with acceptable underwater visibility. In my case it's about 250 miles away, and so videoing is done mainly while on holiday. For me, holiday implies tropical waters and that can imply from £80 to £300 per diving day. |
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When diving, you always dive with a "buddy". Unless you are
very experienced, your holiday dive centre you will ask you and your buddy
to dive within a group of buddy-pairs led by a Dive Guide. Group diving is
a nuisance as the other divers and their exhalation bubbles will get in your
way; just one bubble on your lens will render any footage unusable. Some
of the divers may be photographers with camera mounted flashguns. The blinding
flashes of light will ruin your footage and may scare off many of the larger
creatures. You therefore need to be on your own, with of course your
long-suffering buddy who knows by now when to stop exhaling.
So start now on your quest to become "very experienced". An alternative possibility to group diving and available at some dive centres is to hire your own diveguide. Special trips for groups of videographers would be ideal but don't seem to be available, perhaps because there are relatively few underwater videographers. Or perhaps nobody has thought about arranging them! |
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Under water, the environment and the creatures that you wish to video
will control your possibilities in a variety ways. Different creatures may
live only at specific depths, so that is where you must dive to see them.
You have to understand the environment, learn to use it to your advantage,
and take steps to overcome the obstacles it presents.
The sea is very rarely still. If you and your subject are moving together in a surge, the subject will stay central in your video. But the background will oscillate and make the viewer feel seasick. If you must video in a surge you must use a tripod and select subjects that do not move. Remember to dry and grease your tripod after use, they corrode very rapidly in sea water. |
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But best of all is to choose sites where the current is weak and staying still is not a problem. The other most noticeable effects of the environment are on depth of visibility and the surrounding colour. On the surface on a clear day we can see the horizon 20 miles away. On a good day in the Red Sea we can see 50 metres. On a bad afternoon in the Galapagos the density of the plankton in the water may prevent us from seeing beyond 5 metres. The plankton will of course appear as a myriad of particles in your picture. And if you dive around the UK, then the particles turn the water green as well as reducing the visibility. (Low visibility in Farnes) |
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Water absorbs light quite rapidly and does this according to the colour of the light. At a depth of only 3 metres most of the red light has been absorbed and a red object will appear dark brown. At 10 metres most of the colours have been absorbed and the level of light has fallen drastically. At 30 metres only residual blue light remains. It is possible to account for these colour changes down to a 'depth plus camera-to-subject' distance of about 10 metres by means of coloured (orange/red) filters and adjustment of the camera's white balance. Once set for any combination of depth plus C>S distance, any positive or negative variation in depth or distance from the subject implies either a bluish or reddish tinge to the picture. At depths greater than 15 metres, the picture starts to adopt an uncorrectable bluish tinge. At depths greater than 20 metres, it is frequently necessary to reduce the number of filters used in order to allow for the reduction in overall level of available light; this will increase the bluish tinge. It is sometimes possible to use video lights, but the ones that can be afforded by amateurs are really only suitable for subjects that are very close to the lens. Other advanced options include taking down mirrors - held by your buddy - to reflect additional light onto the subject. Remember to ask your buddy to carry a sheet of white plastic so that you can white balance your camera; alternatively wear white fins. | |||||
You can video anything that is down there, but if you don't want colour tinges, it should be within 3 metres of your lens. You will need a wide-angle lens to video large creatures e.g. sharks, divers and shoals of fishes. Close ups of these creatures can be shot with a standard lens. Small creatures, say 2 cm long, can be shot with a standard lens but you must place the lens only a few centimetres from the subject. Very small creatures, e.g. pygmy sea horse require special lenses and the camera mounted on a tripod. The whole scene should usually have a shallow depth of field. This requirement results from the fact that if the depth of field is large then the surround to the subject will appear blue, OK if the background is water, but not if it is coral. | |||||
© words and images, JohnFletcher |