Princeton Tec EOS Headlamp

Navigation Reviewer Background Product information in brief Delivery & Contents Warranty, Website Introduction Features and Design Future testing strategy

Initial Report

Report Date: December 23, 2004

Reviewer Information

• Name: Edward Ripley-Duggan
  
• Age: 51
  
• Gender: Male
  
• Height: 6' 1" (1.85 m)
  
• Weight: 215 pounds (98 kg)
  
• erd@wilsey.net
  
• Catskills, New York State
  
  

Reviewer Background

I enjoy walking in all its manifold forms, from a simple stroll in the woods to multi-day backpack excursions. Though by no means an extreme ultra-light enthusiast, from spring to fall my preference is to carry a pack weight of 12 lb (5.5 kg), more or less. In recent years, I've rapidly moved to a philosophy of "lighter is better," within the constraints of budget and common sense.

Product information in brief

• Manufacturer: Princeton Tec
• URL: http://www.ptsportlights.com/
• Product: EOS Headlamp
• Year of manufacture: 2004
• MSRP: US $38.99 (from press release)
• Batteries: 3 AAA
• Manufacturer's stated weight: 3.7 oz (105 g) with standard AAA batteries
• Measured weight (digital P.O. scale): 3.7 oz (105 g) with standard AAA batteries
• L.E.D: 1 watt Luxeon with Princeton Tec designed lens/collimator
• Light settings: four modes, three standard at varying levels of intensity, one flashing
• Method of control: "active current control circuit"—from the package enclosure
• Battery life (based on use of alkaline cells, taken from corporate press release):
  High output mode–2 hours of constant brightness / 6.5 hours of run time
  Medium output mode–9.5 hours of constant brightness / 12.5 of run time
  Low output mode–28 hours of constant brightness / 36+ of run time
  
• Waterproofing: "1 m waterproof" according to package (no standard cited)
  
  

Delivery and contents

The headlamp was delivered well packaged and in perfect condition, shipped directly from Princeton Tec. The headlamp was housed in a sealed blister pack. It was mounted within a cut-out in a cardboard display insert. The exterior of this insert lists some basic information about the lamp, as well as the usual display graphics. Unfolded, there are detailed instructions printed on the interior. The lamp ships with three Duracell AAA batteries already inserted in the housing.

Warranty

"Lifetime Warranty. Princeton Tec warrants this product to be free from defects in workmanship and materials under normal use for as long as you own the product. The warranty covers all of the component parts of the product except batteries." Excluded from this warranty is deterioration due to normal wear, misuse, alteration etc. The warranty also details the means and limits of redress at considerable length.

Website

Princeton Tec's website is fairly easy to navigate, although some interesting technical information regarding the lamp (also, as noted, the MSRP) is buried away under the Press Releases page. What is present on the EOS page should be adequate for most potential purchasers.

Introduction

Headlamp technology has come a long way in the past couple of years, thanks to the L.E.D. (light-emitting diode). Not only does this solid-state device offer a superior lifetime over a conventional bulb—10,000 hours is the figure commonly cited—but the L.E.D. also consumes less power, as little energy is dissipated as heat compared to a conventional bulb. The result is a bright, maintenance-free headlamp, generally of significantly lower weight than those of traditional design.

The L.E.D. itself is a cousin of the transistor. Without delving too far into the physics, it is capable of efficiently converting power into light using quantum effects. The light so generated is not white (the exact color is determined by the constituent materials of the diode). However, the plastic surrounding the diode junction contains chemicals that fluoresce over a range of optical wavelengths that is perceived by the eye as nearly white. Most L.E.D's have a slightly bluish cast, although the Luxeon element used in the EOS is without tint to a surprising extent, visually close on a true white.

On an unrelated note, Eos was the Greek goddess of the dawn.

Features and design—initial impressions

The headlamp is attached to a simple wrap-around elasticized headband with no over-the-head strap (of the kind found in many such lamps). The band itself is adjustable (via a plastic buckle system) and is 1 in (2.4 cm) wide. This width is sufficient to give it considerable stability on the head. The strap length provides enough leeway to fit the lamp over a balaclava, hat or perhaps even (though this remains to be seen) a helmet. The strap on the lamp with which I was supplied is gray, with a sort of faux-tigerskin pattern in black, and bears the words "Princeton Tec" prominently on either side. Shaking my head hard, I cannot dislodge the lamp (though I did give myself a slight headache).

The headband passes through slits in the plastic baseplate of the lamp, at which point it is backed with a soft felty material that rests comfortably on the brow. The lamp unit itself is hinged to the bottom of the plate, using a couple of pins that pass through the baseplate into the body of the lamp. The headlamp can rotate through ninety degrees, from horizontal to one's feet. However, if for some reason (for example, searching for trail markers upslope, or for a bird or animal heard but not seen) one wishes to view from horizontal up, it should be possible to quickly remove the lamp and wear it upside-down, so it swivels up.

The headlamp unit has a cream plastic housing, with the back of the lamp (the battery compartment) and the switch (at top) in gray. The aperture of the lamp has a green surround reading "Princeton Tec Regulated LED." Examining the clear cover over the collimator carefully, I noted a number of scratches or marks to the transparent plastic, but this does not seem to have any impact on beam quality.

The battery chassis itself is accessed by unscrewing a single thumbscrew (which is attached to the back of the compartment and thus cannot become lost). Battery orientation in the compartment is indicated both by polarity signs and a diagram of the battery molded into the plastic. It's all quite unequivocal, and simple enough that it may easily prove possible to change batteries in the dark (to be tested).

The lamp is (on its top setting) blindingly bright. While writing this, I accidentally pressed the switch while it was pointed at my eyes, and (a minute later) I was still dazzled. Using a digital luxmeter I compared the light output to my existing headlamp (a good lamp of very recent vintage that has proved more than adequate) and found the EOS approximately twice as bright on its high setting. The switch, which is slightly recessed to avoid turning the unit on accidentally, seems a little stiff. It may prove a trifle tricky to operate in heavily gloved hands. But then again, everything is more difficult wearing heavy gloves or mitts!

Pressing the switch, the lamp lights at its brightest mode; a second press within two seconds, and it is in a mode of middling brightness, one that seems appropriate to trail walking but perhaps not bushwhacking or climbing (but we shall see). Another press, and one has a fairly dim light, suitable for camp chores. A final push, and the light flashes at full intensity at approximately half-second intervals, presumably for signaling purposes. The lamp moves from stage to stage while the selection is made without turning off between modes, an inconvenience I have noted with some lamps. One further interesting feature is that, once a mode is selected (after a three-second interval) a further push of the button will simply turn the unit off, rather than changing it to the next mode. This system avoids the annoyance of having to cycle through brightness levels. When the lamp is next turned on, it will be at maximum intensity, however. The previous setting is not remembered by the circuitry.

To conclude, I will cite the lamp instructions on a point worthy of notice. "Because the EOS uses true current regulation to control power to the LED, it may perform somewhat differently than other products on the market. One peculiarity of current control is that as the batteries wear down there may be no apparent difference between high power mode and one or both dim modes. When battery voltage drops too low to supply more current than that set for a dimmer mode, switching to that dimmer mode will not change the brightness. This is normal behavior." I will be examining the practical ramifications of this.

It should also be noted that the insert contains extensive instructions on drying the lamp in the event that it does get wet.

Future Testing Strategy

Testing will take place between now (December 2004) and May or June of 2005, with temperatures ranging from at least 75 F (24 C) down to -15 F (-26 C); in snow, rain and (I hope) fair weather. Most testing will be conducted in the Catskills of New York State, at elevations to 4180 ft (1274 m), but I expect to take some trips to the Adirondacks (also NY) and the White Mountains of New Hampshire, and possibly some other locales. Over that period I will be hiking at least once or twice a week, backpacking periodically.

In my testing, I will examine the following aspects.

1. How stable over time is the light output? Does the voltage control circuitry perform its job appropriately? This will be tested both in the field and (since subjective assessment of light output is tricky) with a digital luxmeter.

2. In each of the standard illumination modes, does the battery life match the specs?

3. What are the limitations of each of these modes in practical terms? Which mode is optimal for trail use, which for bushwhacking, which for in-camp use?

4. How much improvement over these times do lithium cells provide? How much of an improvement in stability of light output at lower temperatures?

5. How comfortable is the headlamp? Is the strap system, which seems minimalist, stable? Is it easily dislodged by head movement? How does it perform over a hat or helmet? How adjustable is the strap?

6. In practice, how waterproof is the lamp?

7. How easily is the battery compartment accessed? Can batteries be changed with gloved hands? How easily is the switch operated?

8. Is the lamp resistant to moderate impact? How durable is it overall?

9. How easily is the switch operated with gloved hands?

I thank Princeton Tec and BackpackGearTest for the opportunity to participate in this very interesting test.