Even the most colorful reefs in the underwater world becomemuted rather quickly as we descend over the drop-off. The bluewater column we descend through acts as a selective filter thatremoves the reds, oranges, pinks and yellow hues that seem sobrilliant when we light them with our underwater lights. With thesewarm colors missing, the reef and the creatures that adorn it losetheir dazzle until we light them up using a photographic strobe(flash), or in the case of underwater video images, use videolights. Video lights come in two varieties: halogen orhigh-intensity discharge (HID) lights. While both types of videolights will add beautiful color to your underwater footage, it isthe latter of the two, the HIDs, that we'll focus on.
There are several advantages to using HID videolights:
1.These lights are daylight-balanced, meaning that thecolor temperature is the same as sunlight so that when theyilluminate the reef in the foreground and the water in thebackground, both look natural. No special white-balance adjustmentsare necessary when filming with HID lights.
2.HIDs produce more lumens (light power) per watt ofbattery power. That means that smaller, lighter battery packs maybe used to achieve the same brightness level for the same amount ofburn time (how long you can leave the lights on before the batteryis exhausted). Lighter batteries make the camera and the operatorless unwieldy both underwater and as he or she moves to and fromthe dive site.
3.HIDs tend to have a softer, more diffused light output.When shooting with the super-wide-angle lens, this has itsadvantage in that you don't wind up with a distracting spotof light in the center of the image. Most important, soft diffusedlight looks natural and therefore is pleasing to the eye.
Here are a couple of the disadvantages of HID videolights:
1.They tend to be a bit more expensive than their halogencounterparts because of the advantages stated above.
2.HIDs use a ballast when you strike them (start themup), much like the fluorescent bulbs used in offices or in thegarage. The ballast can be a bit finicky, so you need to be patientwhen you strike the lights and learn to pause between tries for aminute or so before restriking. For this reason, many HID usersallow their lights to burn for the entire dive. My experience isthat manufacturers of HID lights have greatly improved upon thisduring the last couple of years.