Backup Lights for Divers

In putting together this review, my intention was to look at the sort of lamp you can routinely take on every dive by tucking into the pocket of your BC. When that awful moment comes when you are unexpectedly left in the dark, you should be able to easily find it, switch it on and read your instruments as you head back out of the darkness of a wreck or cave, back to the surface, and still be found by your pickup boat even during a night dive. Of course, it would be very nice also if you could see where you were going.

Some dive pros would argue that a redundant light should be as good as a primary one, and that you should always treat both in the same manner by checking their operation immediately before diving and maintaining them scrupulously between dives. We divers know who among us stick these things in our pockets and forget them until we need them - - divers are not known to be fastidious about the way they look after their gear.

Brightness is not about how much light is produced by the lamp; it’s about how much light arrives at what you are looking at. This depends very much on the efficiency of the lamp’s reflector, so don’t be misled by the manufacturer’s claims. We give a factor for brightness measured at the end of the beam of each lamp, shone over a six-foot distance, that is equal to the number of times brighter than the dimmest lamp tested here.

The most important aspect of a backup light is not how bright it is or what its light source is, although they are both features to consider when buying one. What’s most important is that it works reliably. Alas, many manufacturers resort to the simple screw-down shroud to employ as a switch. This makes the manufacturing of a watertight product more foolproof but unfortunately does not make for foolproof use by some divers. Reliability is the one thing we can only guess at. The time it takes to test for long-term reliability tends to be more than the commercial lifespan of many products, so you will have to put up with me making an educated guess based on experience.

I, along with other experienced divers, tested 30 dive lights of varying size, price, burn time, light source and brightness factors. Here are five of the best, and five of the not so good, ranked by brightness factor and burn time (all prices are list prices).

The Brightest Lights

UK Sunlight SL4. (Burn time: 4 hours; Brightness factor: 64; Batteries: 4xC; Light source: Single 5.5w Halogen; Depthrated: 500 feet; $42, including batteries; www.uwkinetics.com) Wow! It’s a very old design using old technology, but it provided lots of light in a tightly focused beam and was among the best I tested here. It employs a positive on/off switch that is unmistakable in use. It may be leak-protected by a single O-ring but you never have to disturb it between changing batteries.

Ikelite PCa. (Burn time: 2.5 hours; Brightness factor: 48; Batteries: 6xAA; Light source: Halogen; Depth-rated: 300 feet; $25, including batteries; www.ikelite.com) A useful little lamp that gives lots of light output, albeit in a rather patchy beam, and is protected from flooding by a unique system that clamps on to its single O-ring. The small Ikelite lamps (I also liked the PCLite and the PCm) were among the brightest in this review.

LED-Lenser Frogman. (Burn time: 20 hours-plus; Brightness factor: 24; Batteries: 4xAA; Light source: single high-output 1.5-watt Cree LED; Depth-rated: 200 feet; $52, including batteries; www.zweibrueder.com/english) This neat little lamp uses high-tech electronics to squeeze more light out of its LED than you would think possible. The manufacturer, Zweibruder Optoelectronics, claims it to be 25 times brighter than normal and I can believe it. Early versions proved difficult to turn on at depth but this improved model has a new mechanical switch.

Intova Dive Torch. (Burn time: 3.5 hours; Brightness factor: 16; Batteries: 2xCR123A; Light source: Single highoutput 3-watt LED; Depth-rated: 400 feet; $67, including batteries; www.intova.net) The Intova is a tough, little aluminum lamp with double O-ring protection, plus a gasket, and has no through-body connections to leak because of its magnetic reed switch. It produced a useful amount of light in a well-focused beam and yet it is easily stashed away in a pocket. Despite no proven track record from this manufacturer, it was still one of my favorites.

TekTite Expedition LS4 Aluminium. (Burn time: 15 hours; Brightness factor: 8; Batteries: 3xC; Light source: Single high-output LED; Depth-rated: 2,000 feet-plus; $165; www.tek-tite.com) Exactly the same in performance and function as its less expensive plastic sibling of the same name, this one is machined from marine-grade aluminum and therefore heavier. Double O-ring seals keep the water out. It will give five hours at full power, reducing its output for the next ten. Most appealing to those who like nice-looking gear.

The Dimmer Bulbs

Mares Strobe. (Burn time: 12 hours; Brightness factor: No meter reading possible; Batteries: 3xAA; Light source: 3-watt LED; Depth-rated: 130 feet; $45, including batteries; www.mares.com) More usable as a strobe than a true backup light, this has three unfocused LED lamps at its other end that give out the minimum amount of light. I couldn’t get a reading on my sensitive light meter at six feet of distance. It was quite tricky to install the batteries.

Aquatec AquaStar 3. (Burn time: 6 to 8 hours; Brightness factor: 1; Batteries: 6xAAA; Light source: Single 3 with LED; Depth-rated: 300 feet; $75, including batteries; www.aquatecusa.com) The AquaStar suffers from the common problem of being switched on by rotating the head to bear down onto the battery connection. This can lead to it switching on in your pocket at depth or flooding by unscrewing too far. Only one slim O-ring protects it. The beam was useful but it was not as bright as I would have expected.

TekTite Trek 4. (Burn time: 20 to 80 hours; Brightness factor: 1; Batteries: 3xAA; Light source: 4 LED; Depthrated: 985 feet; $40; www.tek-tite.com) It’s more of a light to be seen with rather than one to see by. It may go on forever but the light produced from its unfocused LEDs is probably little more than you might get from bioluminescence at night rubbing your hand vigorously on your wetsuit -- and that is at full power for the first 20 hours. It gets dimmer after that! It was good for little more than reading your gauges, the second-dimmest lamp compared here.

Tilos S-Sun Headlamp. (Burn time: 12 to 24 hours; Brightness factor: 1.5; Batteries: 2xAA; Light source: 5 LED; Depth-rated: 165 feet; $40, including batteries; www.tilos.com) A head-mounted light that can also be used on the wrist or shoulder too, the S-Sun has three operating modes that are selected sequentially by a single push-button. It didn’t look too well protected against flooding and it has one very skinny O-ring. Light output was poor because the clustered LEDs were not well focused. It was more “dim sum” than S-Sun.

Mares Twin Beam. (Burn time: not available; Brightness factor: 2; Batteries: 1xCR123A; Light source: Single LED; Depth-rated: 165 feet; $70, including batteries; www.mares.com) I unscrewed the light-saber beacon section from this 2-in-1 device to convert it to a little backup light. It’s made of heavy-duty anodized aluminum and has loads of counter-display appeal but its light output was just good enough to read a gauge as a last resort. Quite frankly, it’s not up to the task of a backup light.

John Bantin is the Technical Editor for DIVER magazine in the United Kingdom, a professional underwater photographer and a regular contributor to Undercurrent..