Headlamps can be divided into 4 broad categories by the type of bulb each utilizes: standard, gas (halogen) bulbs, LED (light emitting diode), and hybrid (combination of bulbs). We reviewed several headlamps from each category that retail for less than $40.

Standard bulbs are what appear over your head every time you get a great idea, you know, the kind Thomas Edison invented. These bulbs consist of a tungsten filament housed in a glass bulb filled with Argon and/or Nitrogen gas. Standard bulbs cast a white/yellowish light. The disadvantage to standard bulbs is that they aren't terribly efficient. Most of the energy is lost as heat from the tungsten filament; hence, not all of the energy stored in the battery is converted to light. Standard bulbs have a limited life, usually lasting no more than 1000 hours. This is because the tungsten filament evaporates over time.

Halogen bulbs use a tungsten filament similar to standard bulbs but are encased is a small quartz bulb that contains a gas from the Halogen group of atoms on the periodic table of elements. These gases combine with the evaporating tungsten particles, helping them to deposit back on the filament. This gas effect allows Halogen bulbs to burn longer and hotter (brighter) than standard bulbs. Halogen bulbs last longer (2000 hours+) and cast a brighter beam of light than standard bulbs but drain their power source faster.

LED's or Light Emitting Diodes, are essentially small chips housed in an epoxy casing. As voltage is applied across the chip, electrons jump from one region of the chip to another. When these electrons combine with a positive charge on the other side of the chip, electric potential energy is converted into electromagnetic energy (light). There is virtually no heat produced, therefore LED's are very efficient. The problem with LED's is that they aren't incredibly bright and they don't produce "white" light. LED's can be manufactured which produce red, orange, blue etc. The LED's used in most headlamps produce a very white-blue light.

Comparing brightness and burn time from one headlamp to the next can sometimes be a game of comparing apples to oranges. Some manufacturers choose to list the voltage their headlamps are designed to operate at while others choose to list the wattage of the bulbs supplied. So how do you know which lamp is better without busting out Ohm's law and your calculator every time you compare a flashlight? For the purposes of purchasing a headlamp I would suggest the following criteria: functionality, battery economy, brightness, weight and price (keeping in mind that higher volts or watts means greater battery weight or shorter battery life.) Choose the headlamp that provides the brightness you think you will need while seriously considering the weight of the lamp. There is no need to purchase a headlamp with a super capacity battery pack if your lighting needs will be modest. Conversely, don't get stuck in dark. Balance is the key, error on the side of caution. (I always carry a back up light, which is usually a small key ring type LED).

Petzl Zoom and Micro
Black Diamond Lunar
Princeton Tec Solo
Black Diamond Gemini
Petzl Tikka
Princeton Tec Aurora
Black Diamond Moonlight

Standard Bulbs

Petzl Zoom and Micro (5.3 oz. w/o batteries, 9 oz)
$19.95 & $34.95

Petzl was one of the first companies to mass-market a versatile headlamp. The Micro (and it's big brother, The Zoom) comes out of the box with a standard bulb (3V and 4.5V respectively with battery life of about 8 hours for each), adjustable focus, angle of illumination, and a three-point strap. Both turn on and off by twisting the lenses housing. I have used both headlamps extensively and they have both served me well.

The Micro powers its 3V standard bulb with 2 AA batteries (housed in front) and casts a beam of usable light about 30 feet for about 7 hours (1.5 hours with the halogen bulb). The Zoom does the same job as the Micro but with 4 AA batteries (housed in back), a 6V bulb, and larger lenses giving a brighter beam and farther coverage. While I have found the Micro an asset while trail hiking and performing campsite tasks, it isn't my first choice for off trail conditions or rock climbing. Route finding 30 feet at a time can be a hassle. The Zoom is a good choice for more extreme conditions but its size and weight make it less appealing. I would sooner carry a halogen bulb for my micro, and switch it out with the standard when I need more light, than carry the larger Zoom.

BackcountryStore.com carries the Petzl Zoom and the Petzl Micro.

Contact Petzl USA at 877-807-3805 or on the internet at www.petzl.com.

Halogen Bulbs

The Black Diamond Lunar (6.8 oz)
$24.95

The Lunar is a well-manufactured headlamp with many similarities to the Petzl Micro; you might even call it the Micro's rich Halogen cousin. The long-life xenon halogen bulb is powered by 2 AA batteries (burn time 7 hours). Its powerful adjustable beam is cast nearly 7 times farther than the standard bulb micro beam. The Lunar is turned on and off by a push button switch mounted on the lens housing and has a 3-point strap similar to the Micro. A noticeable difference between this headlamp and the Petzl Micro is in balance, which is endowed by the Lunar's rear-mounted battery pack. While this headlamp definitely will light your way, it will also eat through your batteries quickly, especially if you enjoy reading in the sack. When the bright xenon bulb is installed in this headlamp the output of light seems to be nearly doubled, right along with your battery consumption. Given the brightness of this replacement bulb, the Lunar could have been named the "Solar".

If you're interested in purchasing the Black Diamond Lunar, check out BackcountryStore.com.

Contact Black Diamond Equipment at 801-278-5552 or on the internet at www.blackdiamdondequipment.com.

Princeton Tec Solo (6 oz.)
$24.95

The Solo is the fraternal twin (separated at birth) to the Black Diamond Lunar. It has many of the same features such as a three-point head strap, interchangeable bright and long-life bulbs (powered by 2 AA's) and similar weight and cost. The differences are striking however. The Solo has two interchangeable fixed focus reflectors which Princeton Tec claims produces higher quality beams compared to adjustable focus lenses. The batteries are housed in the front of the unit and this headlamp is waterproof to 2000 feet (necessary if you're Robert Ballard searching for the Titanic). According to Princeton Tec, the Solo is the, "#1 selling headlamp in the outdoor marketplace.

You can purchase the Princeton Tec Solo for $24.95 at REI online.

Contact Princeton Tec at 609-298-9331 or on the internet at www.princetontec.com.

Hybrid

Black Diamond Gemini (5.3 oz w/o batteries)
$38.50

The appropriately named Gemini (implying a metaphorical relationship between the halogen and LED bulbs, and Castor and Pollux, the two brightest stars in the likewise named constellation of the zodiac) has a foot in each bulb world by having both a long-life halogen and LED bulb. The conveniently located, three-function push button switch, allows the user to toggle between a bright (battery draining) halogen bulb, a subordinate miserly LED and the OFF configuration. Don't take my use of the word subordinate the wrong way. I use the, surprisingly bright LED, far more than the halogen bulb. This is the perfect headlamp for outdoor enthusiasts that need a bright light on occasion, that also gives the user the opportunity to conserve batteries while having plenty of light for campsite duties with the LED bulb. The Gemini is well balanced in both candlepower and weight, with the back-of-head located battery pack and a 3-point strap. Three AA batteries are required and this headlamp has a fixed focus housing, but you can adjust the angle of light. As with the Black Diamond Lunar, this headlamp comes with a bright halogen replacement bulb, and switching them in the dark is a cinch if you leave the LED on.

Visit BackcountryStore.com to see pricing and availability of the Black Diamond Gemini.

Black Diamond Equipment can be contacted at 801-278-5552 or on the internet at www.blackdiamondequipment.com.

LED

Petzl Tikka (2.5 oz)
$34.95

The Tikka, which was one of the first LED headlamps on the market, is powered by 3 AAA batteries and has an advertised burn time of 162 hours with the first 12 hours at maximum output, and the light output continues to decrease the more you drain the batteries. The Tikka has one strap and the battery pack is convenient located and easy to access. The Tikka only has one brightness setting and is turned on with a flat switch that moves sideways. I found the switch difficult to operate with gloves on, but this is a minor problem unless you are turning your headlamp on and off frequently. The biggest disadvantage to this headlamp is that the angle of illumination isn't adustable.

BackcountryStore.com sells the Petzl Tikka for $28.95.

Contact Petzl USA at 877-807-3805 or on the internet at www.petzl.com.

Princeton Tec Aurora (2.6 oz)
$29.95

Princeton Tec has lived up to its "Atlantis to Everest" motto with the introduction of the Aurora. This LED headlamp, which is very similar to the Petzl Tikka LED headlamp, has 3 LED bulbs arranged in a triangular configuration providing even lighting throughout your field of view with no blank spots in the beam. The Aurora has 5 lighting modes: Bright, Medium, Dim, Slow Strobe and Fast Strobe all controlled with an easy-to-operate pushbutton switch. The Dim mode is bright enough for reading and the Bright mode is bright enough to trail hike with.

The Aurora is powered by 3 AAA batteries and has an advertised burn time of 200 hours. The biggest advantage this headlamp has over the Tikka is that you can adjust its angle of illumination. It surpasses the Black Diamond Moonlight in three ways: price, weight, and that with the Moonlight you have to physically remove 2 of the 4 LED bulbs to conserve precious battery power whereas with the Aurora this is accomplished with a click of the push button switch.

One of the best liked headlamps in this review, the Aurora can be purchased at REI Online.

Contact Princeton Tec at 609-298-9331 or on the internet at www.princetontec.com.

Black Diamond Moonlight (3.2oz)
$34.50

The Black Diamond Moonlight is an excellent LED headlamp. Its 4 LED bulbs are powered by 3 AAA batteries housed on the back of one of two head straps. This well balanced lamp provided ample light to trail hike and read with and includes the option of reducing battery use by removing 2 of the 4 LED bulbs. The angle of illumination is adjustable, a feature any good headlamp worth its weight and price should have.

I mentioned in the note at the beginning of this review that I always carry and back-up light. The Princeton Tec Aurora, Black Diamond Moonlight and the Tikka all fit that bill perfectly when the power of a halogen is required as a primary light source for nighttime mountaineering or off-trail hiking. If one of these headlamps is your primary light source you could easily use the Princeton Tec Pulsar 2, which is a small key ring LED with an on/off switch (no more bite marks on my "emergency light"). The diehard ultra-lite hiker reading this will think he can get by with just the Pulsar 2 and truth be told, she probably could!

The Black Diamond Moonlight can be purchased online at BackcountryStore.com.

Black Diamond Equipment can be contacted at 801-278-5552 or on the internet at www.blackdiamondequipment.com.

Summary:Choosing the correct headlamp(s) for your outdoor adventures is easier than you may think. As long as you consider functionality, battery economy, weight and price, you will be led to the best piece(s) of gear for your needs. I am really not a fan of interchangeable lenses, bulbs and add-on gizmos. Simple is better in my opinion. I found that any of these head lamps could meet my basic needs in most situations but because I need a head lamp that can serve me well in extreme situations such as mountaineering and rock climbing I prefer the balanced combination of versatility, weight, and price both the Black Diamond Gemini and the Princeton Tec Aurora offer.

Dave Allison is a new contributor to GearReview.com, specializing in ultralight backpacking, climbing, and mountaineering.