for diving, beam angles are described as spot or flood. A narrow spot beam works well in daylight or for looking into holes.
Only a couple of the lights tested had pinpoint spot beams without edge lighting. Most had a bright centre spot with dimmer, if still very usable, light radiating out. This is useful for seeing your surroundings, and makes for a good back-up at night or in overhead environments.
A 700-lumen, 30° beam pocket torch used as a primary night-diving light.
A flood beam lights a far larger area, essential for seeing where you’re going, such as in a cave but less effective for looking into nooks. Those used for diving are usually narrower than those used for video lights, which need to be matched to the angle of your lens or they will hotspot. Wide-beam compact video lights aren’t usually much good for diving.
Most dive-lights with a flood beam strike a compromise that lets you see a fairly large area with good distance penetration. Some have adjustable focus, so the beam can be zoomed in or out to narrow or widen it.
Smooth reflectors are usually used for spot beams, dimpled ones for flood beams. In either case a well-designed reflector yields a smooth, even light.
Light duration or burntime is a consideration if you want to use your light for several dives without having to charge or change batteries. How long are those dives likely to last?
Increasingly lights, even in the economy range, use rechargeable batteries, usually lithium-ion cells. Their performance figures as quoted by the manufacturer should be fairly accurate – less so those of single-use batteries.
Some lights sold as rechargeables can also accept single-use batteries if you can’t recharge in time for your next dive. All but one of the tested rechargeable lights have removable cells, so you can just switch to a spare.
The GoBe is a sealed unit. This significantly reduces risk of flooding through user error, but you need to have time to recharge it. All of the featured rechargeables use a USB charger.
All three common styles of switch are found among our test group. The simplest is a screw-down front bezel. Turn it the wrong way and you’ll eventually flood your light. At depth, pressure can also turn the light on inadvertently.
As long as you guard against this, the design does eliminate potential leak points. You’ll usually need both hands for switching.
A mechanical or magnetic switch turns the light on and off but also enables adjustments such as brightness or SOS functions. It can normally be used one-handed. None of the lights tested, except the GoBe, had a switch-lock to prevent accidental switching on.
Slim batteries allow torches to be thin-bodied, but it’s a good idea to see whether the light will be comfortable in your hands for long periods, especially when using thick gloves, and that you can easily operate its switch.
Attaching your light to your mask-strap or a helmet rarely works well. It might help when reading instruments, but you’re likely to find yourself looking head-on into the backscatter.
You get a lot of light technology for a modest investment these days. There’s still a trade-off to be made between output, beam-width, burntime, size and price, but among the 10 lights tested below, you’re spoilt for choice.