The following are the main variables that differentiate headlamps:

Shop REI's selection of headlamps.

Headlamps in a Nutshell

If you're in a hurry, here's a crash course in headlamp selection:

1. Look for lumens. Lumens tell you how intensely a light glows at its source.
2. Look beyond lumens. Lumens tell a big part of a headlamp's story, just not its total story. (Not everyone, after all, needs a headlamp that blazes with 350 lumens.) What really matters is how well (and for what length of time) a headlamp illuminates a target area—the trail in front of your feet, for instance. A headlamp's true value lies in how effectively it uses its lumens to accomplish these tasks. Several other specs are also useful for evaluating headlamps:
   • Beam distance (how far the lamp can project "usable light").
   • Run time (battery life).
   • Size and weight.

The following sections provide details on headlamp specifications.

Light Output (Lumens)

• Reported in lumens (not watts).
• Determined when batteries (the same type sold with the headlamp) are new.

Lumens are a unit of measure that gauges the total quantity of light emitted in all directions by a light source. Watts, traditionally featured on the packaging of conventional household light bulbs, are a measure of how much energy a light uses. Typically, though, a light with a high lumens count will consume energy at a higher rate than a light with a lower lumens number.

So, the higher the lumens, the brighter the light? In most cases, yes—but not necessarily. Lumens are measured in a spherical device, capturing light emitted in all directions by the source. Yet how well a headlamp maker focuses and directs that light (via lenses and reflectors) can impact how those lumens are utilized. If, for instance, a headlamp uses a translucent casing, some lumens will escape through that casing and not contribute to the overall strength of the beam.

Where to Find Lumens on Headlamp Packaging

Manufacturers are rarely shy about touting lumens on their packaging, believing that most consumers will simply associate a high number with superior performance. ("Ha! My headlamp is a 75. What's yours?") A lumens count is useful to know, but it is just one of several factors that tell a headlamp's complete story.

Beam Distance

• Reported in meters.
• Determined when batteries (the same type sold with the headlamp) are new.

Lumens tell you how brightly a headlamp glows (at its source), but not how far it goes (to a surface you want illuminated). This is a headlamp's fundamental purpose—to channel light to a target area.

Headlamps are tested to determine how far (in meters) they can project usable light, defined as the light cast by a full moon on a clear night. In the lighting industry this is known as the "moonlight standard," which is especially relevant to outdoor adventurers.

The light of a full moon, unless obscured by a dense tree canopy, is considered sufficient light for a person to navigate cautiously but safely through outdoor terrain.

To meet that standard, a light meter must be placed on a surface and register a minimum reading of 0.25 lux (the light intensity of a full moon). Lux is a measure of light where it falls on a surface that it illuminates.

To envision how beam distance is tested, imagine a headlamp with fresh batteries attached to a fixed position. It is switched on, placed on its highest mode, and a light meter (technically known as a lux meter) is moved further and further until the meter, measuring the center of the headlamp's beam, registers 0.25 lux. That is a headlamp's maximum beam distance (which slowly grows progressively shorter as batteries are drained). This number is usually prominently displayed somewhere on packaging. Some brands also display beam distance numbers for lower-intensity settings.

Where to Find Beam Distance

While each manufacturer uses the same test for beam distance, they display the results differently, a fact that can frustrate consumers. (Us, too.) Some day we hope manufacturers will agree to a uniform presentation of test results (something like standardized nutrition labeling on food products) so everyone finds it easier to make apples-to-apples spec comparisons.

Run Time

• Reported in hours (for example, 50h, meaning 50 hours).
• Determined when batteries (the same type sold with the headlamp) are new.

Here is where headlamp makers part company with the ANSI/NEMA test standard. That standard declares batteries reach an exhausted state when a light can produce only 10% of its original light output (when batteries were fresh). This is usually determined with a measuring sphere.

That would leave a number of high-powered headlamps with a lot of energy still in the tank—still possessing enough battery power to project usable light (the light of a full moon). A high-intensity beacon such as the Peztl Ultra (rated at a dizzying 350 lumens) would still have a very serviceable 35 lumens of light available at 10% of original output.

Since most outdoor adventurers can function safely in an emergency mode with good moonlight, headlamp makers calculate run time until lights can no longer produce usable light (the light of a full moon) at 2 meters.

Why 2 meters (6'6")? The average American height is 5'9½" (male) and 5'4" (female), according to the Centers for Disease Prevention and Control. Thus headlamp makers consider a headlamp serviceable if it can project 0.25 lux, the equivalent of a full moon's light, on the terrain in front of an on-the-move adventurer in the dark. It's a legitimate calculation that REI's Quality Assurance Lab endorses. This is usually measured with a lux meter.

Where to Find Run Time on Headlamp Packaging

Look for a clock icon plus a number of hours (usually shown in abbreviated form, such as 50h). If just one number is shown, this is the measurement of the light's lowest (most energy-efficient) setting for continuous light. Some brands show run times of all modes (low, high and in-between). The blinking strobe mode is a headlamp's most energy-efficient mode, followed by low.

Size and Weight

Most headlamps, with batteries included, weigh less than 7 ounces. Size-wise, most headlamp units range between the size of a golf ball and a racquetball.

Accordingly, you won't notice substantial differences in headlamp size and weight until you start examining some very high-powered models. Some have top straps and external battery packs that add bulk. Such models are intended for specific needs (climbing, for example) and are usually not necessary for routine adventures.

Most packaging displays headlamp weight in grams. At right are some random conversion figures to speed up mental calculations for non-metric minds.

Other Headlamp Considerations

You may not know your preferences on all of the following secondary topics right now. Don't fret. Such understanding is usually gained only after much fiddling in the field, where you compare headlamp notes with your backcountry buds and become an official, obsessive headlamp geek. And there are plenty of us out there.

Modes

Most headlamps offer at least a high and low mode. Others may offer 3 or more modes, alternately called "brightness levels." Here's a breakdown, moving from the most energy-efficient mode to the least-efficient:

• Strobe (or Flash): An emergency blinker. A few models even offer a choice of flash rates: slow and fast.
• Low: The standard mode used for most tasks such as camp chores or walking along an easy trail at night.
• Mid: Provided on some models simply to give people more choices.
• High (or Max): A good option for situations where you simply need or want more light.
• Boost (or Zoom): Found on just a few models, this feature permits an extra-intense beam to be projected for a brief period, maybe 10-20 seconds—nice to have when you're really curious about what's causing that rustling sound in those nearby bushes. Just realize this mode exerts a high drain on batteries.

Red Light

Some headlamps offer a red-light mode. Red light does not cause our pupils of our eyes to shrink the way white light can, so it's nice to use when viewing the night sky.

Beam Width

Some headlamps offer a fixed beam width; others are adjustable. Two fixed widths are:

• Flood (or Wide): Useful for general camp tasks, up-close repair work and reading. Less likely to momentarily blind companions in case they inadvertently catch an eyeful of your beam. Flood beams ordinarily do not throw light a long distance.
• Spot (or Focused or Narrow): Tight beam is better equipped to enable long-distance viewing. In most cases this is a better choice to navigate a trail in the dark.

Adjustable beams give you options. Manufacturers have different ways of conveying this feature on their packaging. Typically it involves combined imagery of both wide and narrow beams.

Beam Quality

A strong center beam is not necessarily indicative of a great headlamp. A laser beam, for example, projects an incredibly powerful beam of light but is so narrowly focused that it illuminates virtually nothing.

Some headlamps may not throw light the longest distance, yet they do a nice job of filling its beam with an even density of light, so a larger surface area of an illuminated object will be brighter overall across a wider area.

This is often a desirable attribute. Some lights that cast long beam distances project a very strong center axis of light—so strong that it creates an extra-bright center spot during up-close viewing, such as reading a map. During extended viewing, a bright center spot can create a glare that becomes annoying.

Headlamp packaging does not convey beam quality information, primarily because it's tough to verify through any objective measurement. Some manufacturers individually test for "beam fill" by evaluating the density and evenness of a beam's strength as it falls on a broad 9-point grid (3 points high, 3 wide). If a headlamp claims enhanced beam quality, you'll probably find it mentioned only in its product description.

Lithium Batteries

Do not use lithium batteries in a headlamp unless manufacturer instructions specifically state that a particular model can accommodate lithium cells. The high nominal voltage produced by lithium batteries could damage or ruin a light's circuitry not equipped to handle such power.

Headlamps designed to work with lithium batteries are a good choice for cold-weather usage, since lithium batteries outperform alkaline batteries in cold conditions.

Rechargeable nickel metal hydride (NiMH) batteries also work well with headlamps and perform well in cold conditions. Read more about battery choices in the REI Expert Advice article How to Choose Batteries.

Tip: Carry spare batteries on any adventure, even a day trip. We love rechargeable batteries, but because rechargeables tend to lose power when sitting idle, it's smart to carry alkalines (excellent at holding their charge) as backup batteries.

Regulated Output

Rather than gradually dimming as batteries drain, regulated headlamps offer a steady brightness level throughout the life of the batteries. It is understandable why many people consider this a nice feature.

The downside: When batteries are exhausted, the light of a regulated headlamp can go dark abruptly. This may leave you scrambling to replace batteries in the dark. A dimming light on an unregulated headlamp gives you early warning that batteries are nearing the end of their usefulness.

Both approaches have advantages and trade-offs. Neither is considered superior.

Other Features

• Water resistance: All headlamps sold at REI are able to withstand exposure to rain and snow. (They can handle modest drops and jolts, too.) A few can tolerate shallow, short-term immersion. None of the models offered in REI's camp/hike assortment are designed for prolonged underwater submersion.
• Tilt: Can the tilt of the headlamp unit be adjusted up and down? It's nice to have that option in order to position the beam exactly where you want it. This especially comes into play while reading by headlamp.
• On/off switches: Some headlamps switches lock to prevent a headlamp from being inadvertently switched on inside a pack. (That's a nice feature.) If you're examining headlamps at a store and demo models are available, play with the buttons. Do you find them easy to activate? Are they somewhat glove-friendly? Are you content with how the headlamp cycles through its modes? I prefer starting on low, then ascending; others want the brightest mode on first push. Headlamps vary in their approach.
• External battery packs, top straps: Some headlamps (usually high-power models that use 4 batteries) position the battery pack on the rear of the headband and run a small cable from the pack to the headlamp. It lightens the load on your forehead but can feel clunky. Top straps (sometimes removable) may be included on some models to add stability.
• Lantern adapter: Mammut offers a miniature plastic globe that clips onto 3 of its headlamps. When attached, you can suspend the headlamp somewhere overhead and allow globe to disperse light around a modestly wide area. Smart.

LEDs (Light-Emitting Diodes)

Headlamps today almost exclusively use LEDs (a type of semiconductor) as their light source. A few hybrid headlamps combine LEDs with conventional gas-filled bulbs, yet advanced LEDs now rival the light intensity of bright-burning Xenon bulbs while providing several advantages. Among them:

• rugged (no glass or filament to break)
• energy-efficient (they drain batteries 3 to 5 times slower than incandescent bulbs)
• long-lasting (can last up to 100,000 hours vs. 40 for some bulbs).

Beware of buzzwords you might see on some packaging. Some manufacturers claim their LEDs are "superbright," "ultrabright," "TriplePower" or some similar form of megaspeak. Don't be impressed. Such terms are pure hype, not industry-recognized technical classifications.

LEDs come in various sizes (based on their diameter—1mm, 3mm, 5mm and larger), and larger usually means brighter. Some do fall in a legitimate category known as high-output LEDs, based on wattage (their ability to draw more energy). Expect bright output by any lamps that feature 1-watt or 3-watt LEDs.

LEDs used in headlamps are "tuned" to produce a white light. (Explaining how this is accomplished can be mind-numbingly technical, involving discussions of spectroradiometers, "chromaticity coordinates" and other arcane topics). Just understand that headlamp LEDs tend to have a faint blue cast to their light. This boosts their energy efficiency, since turquoise offers the most desirable wattage-to-lumen ratio. The most energy-efficient color of all? Red.

Increasingly rare these days, hybrid headlamps combine LED and pressurized-gas bulb light sources. (The few hybrids REI carries can be found only at REI.com.) The bulbs are usually the bright-burning xenon variety. Xenon bulbs still offer greater light intensity than even high-output LEDs (and some cavers insist on them), but the margin of difference has grown fairly thin. The substantial advantages LEDs offer in energy efficiency and durability have made them the light source of choice for most headlamps.

ANSI/NEMA Standard

In late 2009, with input from more than a dozen manufacturers and other companies involved in the lighting industry (including REI), the National Electronic Manufacturers Association (NEMA) published ANSI/NEMA FL 1-2009, Flashlight Basic Performance Standard. ANSI is the American National Standards Institute, a private, nonprofit organization that oversees voluntary consensus product standards in the United States.

The dual goals of the standard:

• Create uniform test methods for all portable, single-direction lighting devices.
• Present test results in a uniform manner (through the use of common icons), making it easier for consumers to interpret results.

Compliance with the standard is voluntary and, as mentioned earlier, headlamp-makers disagree with majority opinion when it comes to determining run time (preferring to apply the moonlight standard to headlamps). In all other areas, however, headlamp-makers conform to the test methods laid out in the ANSI/NEMA standard.

Overall, we at REI believe the standard is a good thing. What disappoints us is that every manufacturer displays test results in different ways and it is tough for consumers to make quick performance comparisons between different brands. We have attempted to point out where to locate comparative information in our "Where to Find" descriptions earlier in this article, but we still wish the process was easier for everyone.

Best Headlamps by Activity

Of all the factors discussed in this article, which matter most? Brightness (light output) is high on everyone's list, but beam distance and run time also factor into the total picture of a headlamp's performance potential.

The nature of your outdoor activities will also play a role in your decision. Here are some basic guidelines:

Shop REI's selection of headlamps.

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