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DiveRite H10 Compact
Fa-Mi 2004 S12 Stilo HID
GreenForce F2 100 Compact HID
Halcyon Proteus 3 HID
Kowalski Speed Xenon
Luminator HID
NiteRider HID
OMS Phantom 10
UK Light Cannon 100
If it's a really bright underwater light you want, then HID, or High Intensity Discharge, is the way to go. But there are disadvantages, too, and cost is one of them. John Bantin goes in search of the good-value performers that really shine
CONTRARY TO POPULAR BELIEF, Thomas Edison, the Italian-American inventor, did not invent the electric light bulb. Edison simply improved on an existing 50-year-old idea. Since then, many other people have been trying to come up with even better ways of shedding light, including the invention of the coiled-tungsten filament.
Seventy-nine years before Edison's patent, Englishman Sir Humphrey Davy invented the first electric lamp, and it used a carbon-arc. Arc-lights were at one time the answer to illumination for the theatrical world, where incandescent glows were simply not bright enough.
Technology has moved on a lot since then, and lighting has been produced for all manner of specialist applications. That includes high-output, long-lasting light sources for surgeons in operating theatres, often known as High Intensity Discharge lamps. These are a development of the traditional arc-light rather than the more common descendant of Edison's tungsten bulb.
HID can be found not only in operating theatres but on high-performance bikes and in industrial-fibre illumination. The lamps burn brighter than a traditional halogen bulb and, because they require less power, have greater battery burntime. They also produce a light more akin to the quality of daylight, which, on a typical sunny day with white clouds, is around 5500űK.
While tungsten bulbs give a rather warm yellow light at around 3200°K, HID lamps can give a light approaching anything from 4500°K up to 6000°K. It's colder or more blue in appearance.
Blue light penetrates water better than yellow light, although it should be said that we tend to be more comfortable looking at things by a warmer light. It's a question of compromise, but in Diver Tests we have found that lights which were closer to natural daylight were more user-friendly.
Always quick to pick up on anything likely to give an edge over what might otherwise be available, some diving light manufacturers saw the additional advantages of HID.
These included better water-penetration because of the higher colour temperatures possible, the higher output watt-for-watt over tungsten bulbs, and the long battery duration associated with HID.
The only disadvantages seem to be that lamps equipped with an HID light source are at the less reachable end of the price spectrum, and the time they take to fire up.
We identified more than a dozen manufacturers offering HID diving lights, but only nine were able to come up with the goods when we asked them to send us a sample for this comparison test. So we deduce that these are the makes commonly available in the UK. Most had Solar brand lamps within, and these are manufactured by Welch Allyn Lighting Products in New York state.
Instead of a conventional bulb with a filament safely protected inside a glass envelope, HID lights have a visibly contrived arc which, once fired up, needs time to reach normal working temperature and full light output.
This means that you must turn an HID light on and wait a moment. It also means that you should not turn it off until you have finished with it.
You can damage an HID, too, if you switch it off before it has warmed up properly. Similarly, you need to wait after switching it off before switching it on again. This is referred to as "restart time". The longevity of the expensive-to-replace HID arc is related to the number of times it is fired up, rather than the duration for which it is alight.
So if you want to turn the light off during a dive, it's best simply to occlude it against you body. In fact you should do this with a conventional tungsten lamp as well, because it is the sudden current-surge caused by switching it on which is likely to make the bulb blow.
Some of the lights here are merely one example of a range that might be available from that particular manufacturer. Most are available in a "lamphead-with-umbilical-to-battery-pack" format. Others come only in a conventional lantern format.
They vary considerably in size, but we weighed them in water and give a weight for both the lamphead (approximate) and for the whole unit.
However, remember that a battery-pack fixed to your tank substitutes for weight on your weightbelt, but a one-piece lantern is an extra weight in your hand.
Brightness factors were measured at the brightest point in the beam, and are relative only to lights in this test rather than some universal measure.
Your eyes have a fantastic ability to adjust to a wide range of brightness levels, so unless you are diving with someone who has a very different light, the main difference is between having a light that works and one that doesn't.
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