Home : Video course : Module 4: Lighting Underwater

What to look for

Unless you plan to shoot all your video footage within a couple of metres of the surface you will need to take your own light source with you to restore colours and increase contrast. Unfortunately, you cannot use ordinary dive torches for shooting video because they are not powerful enough and nearly always have a hot spot in their beam. A purpose built video light is the solution - but which one?

Batteries

You need a lot of power to run a video light and so the efficiency of the batteries is a major factor in determining any particular unit's efficiency.

It is only cost effective to use rechargeable batteries in video lights (given the power demand). These are usually industrial grade Ni-MhNickel Metal Hydride batteries are very efficient and offer about 40% more capacity than NiCD plus they dont suffer from memory effect. However they only last 500 charge and discharge cycles. NiMH batteries lose about 3% of their charge daily. cells (ni-cads) and you may or may not get a charger included in the cost of the light.

Burn Time

Burn time is perhaps the most important characteristic to look at when choosing a video light. This is simply the time that you can run it for. Most lights run for no more than 40 mins. In practical usage however, you do not use your light continuously and may get a couple of dives out of it. In any event, you are also limited by the maximum run time on your camcorder battery.

Lamps

The power of lamp you need is a matter of personal choice but as a general rule you need more powerful lights for clearer water (the opposite of what you might expect) because there is more ambient light for it to compete with.

Chargers

Whatever your light's burn time it is also important that your batteries will take a charge quickly so that you do not miss a dive when the inevitable happens - and you run out of power. It has to be said that fast chargers do curtail the life of your batteries though.

Fast or slow, your charger should ideally be dual voltage so that you can run it anywhere in the world. It's also good advice to buy a spare ni-cad pack to swap over to in the field.

Size and weight

Unfortunately, due to high power consumption, you have a weight penalty for the batteries. The weight, and size becomes important when you travel a lot and want to keep your excess baggage down to a minimum. If you could invent a power source of 4.5 AH that weighed only a couple of ounces then you could make a fortune!

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