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HOW TO BUY A DIVE LIGHT

There are a couple of unalterable truths about diving that make the purchase of a dive light an excellent idea. (1) If you’re diving at night, you won’t be able to see anything without a light. (2) Even during a daytime dive, a light is useful for peeking into cracks and crevices. (3) A candle in a baggie simply won’t do the trick.

TIME OF USE - Simply put, nighttime diving presents different illumination problems than does daytime diving, and will mandate a different choice in dive lights. So your first decision should be to examine when you’ll be using the light. If you’ll be using it primarily at night, you need to think about overcoming total (or near total) darkness which probably means a wider beam angle and a fairly bright light. For daytime diving, the need for illumination is limited to peering under ledges, in holes, and the like, which means you can use a light with a much narrower beam angle, and without as much candlepower.

BEAM WIDTH - This simply refers to how large an area the light covers. But there’s a trade-off between beam width, brightness of the light, and power requirements. The wider the beam, the less bright it will be, unless you increase the power (and usually the price) of the light. A narrower beam will be brighter but covers less area. So unless you want to dive with a couple of car batteries strapped to your back for power, you’ll need to decide if "wider" or "brighter" is more important to you.

BRIGHTNESS - One way the manufacturers have dealt with this is to create lights that have two beam areas. The primary area is the bright spot in the center of the overall beam. The secondary area is a much dimmer (and wider) area outside of the central primary area. By constructing a light this way, you can get some of the advantage of brightness and width, without having to tremendously increase power.

TESTING FOR WIDTH - The easiest way to see how wide (and bright) a beam is, is to go to your local dive shop, and shine the light against a wall. This is also a great technique for comparing two lights as you can shine them side-by-side. But it’s important to remember that, in the water, your light beam (because of the water’s density) doesn’t go much more than 5-10 feet. So that’s how far you should stand from the wall when you’re testing a light so the beam width and intensity will be similar to what you’ll see underwater.

BRIGHTER IS NOT ALWAYS BETTER - An initial impression might be that you want the brightest light on the market. But that’s not always the case. If you dive in water that’s especially turbid or has a lot of suspended particles, a brighter light may actually hamper your visibility as it tends to make those particles more visible. However, if you’ll be diving in water that’s generally pretty clear, a brighter light &/or a wider beam will allow you to see more stuff.

If you’re a photographer shooting at night and using a dive light as a spotting light, you may also want to think about something slightly less bright. Very bright lights can spook the very fish you’re trying to shoot, as well as give you a "hot spot" in the center of your picture (depending on the f-stop and film speed you’re using).

SIZE & WEIGHT - Dive lights best suited for nighttime diving will generally be larger than their daytime cousins, which can usually be slipped inside a BC pocket. But since you’ll be keeping the light on all the time and using it 100% throughout the night dive, size is not really an issue because the assumption is that you’ll be holding it in your hands.

A daytime light, since it doesn’t need the candlepower to light up the evening reef, will be relatively small and compact. It should fit comfortably in your hand with the on/off switch readily accessible. And since you’ll probably use it at various times during the dive, you want to see that it fits comfortably inside your BC pocket.

BATTERIES vs. RECHARGEABLE - The advantage of batteries is that they last a relatively long time. But since you use up some of the charge each time you turn on the light, the strength of the batteries diminishes over time, which means your light will slowly be growing ever-so-imperceptibly dimmer. But all it takes is a fresh set of batteries to restore the light to it’s original intensity.

Rechargeable batteries will give you a more consistent level of light output. But when they start to go, they go pretty fast. And while it’s unusual for a battery-powered light to die during the dive (you’d have noticed it was getting dim and changed the batteries before they were fully drained), it’s not unusual for a rechargeable light to wink out on you towards the end of your dive. But all you have to do is plug the light in for the recharging period, which can be anywhere from a few hours to overnight.

If you’ll only be using the light for one dive a day, a rechargeable can be a great way to go (though they are a bit more expensive). If you’ll be using the light a lot without much down time, you might want to stick to batteries. Many divers use a battery light for their daytime light, and a rechargeable for their night diving light, with the daytime light serving as nighttime backup.

LANYARDS - Most lights come with a lanyard (to attach the light to your wrist or to a piece of your equipment). If the light you’re looking at doesn’t come with a lanyard, buy one. It’s cheap insurance against losing the light.

SPECIALTY LIGHTS - A couple of manufacturers make dive lights (mostly for nighttime use) that fit on your head or mask strap. These are especially useful if you want to have your hands free as the light will always be pointing in whatever direction you’re looking. (Just remember not to stare into your buddy’s mask or you’ll blind him/her.)

OTHER GOODIES - Its’ always good to carry an extra bulb, a spare lanyard, and extra batteries with you. And with some of the bigger lights, you may also have the option of switching between a pistol grip and a lantern grip.

There’s a world of wonder that lurks in the shadows of the reef. Go grab a light, slip into the water, and (literally) see what you’ve been missing.


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