Field and test information
Summer, with its long days and warmer temperatures, has been the background for the Long Term test. Other than one week in which we received record-breaking (and locally disastrous) rains, the weather has generally been typically warm and only intermittently wet, with night-time temperatures at elevation down to perhaps 60 F (16 C); perhaps a bit cooler. Use was primarily in the Catskill Mountains of New York State, and included a backpack traverse of the Escarpment Trail. Due to the long daylight hours, the lamp saw no use on day hikes in this period, but it was used extensively as a utility lamp at home and in the vicinity, for everything from installing an air conditioner after dark, to nighttime road-walks.
Product Use and Performance
The Apex headlamp
As I had stated in the Field Report, the Apex headlamp really comes into its own when leading groups of hikers, but further testing over the last two months has demonstrated that it is by no means an underachiever as a headlamp for general use. I have used it as a camp light: for cooking, setting up my tent, general campsite illumination etc. The highly focused Maxbright LED is not needed in camp, I've found (somewhat predictably). I chose instead to use the two standard Ultrabright LED settings, and I have found them more than enough for these purposes. The Ultrabright settings have the advantage of saving battery power. Also (and this is a real concern) my companion was not temporarily blinded. The intensity of the three-Watt LED is such that the resulting dazzle can be extremely uncomfortable to others, so it's not really a setting I have found useful for general camp use, but it surely comes into its own on the trail. I have experimented with the flashing mode of the Ultrabright, but I've not had practical occasion to use it for signaling. I have briefly used it while riding my bike at twilight to enhance my visibility. Still, it doesn't hurt that it's available.
I consider this to be easily the brightest headlamp I have ever owned. I can't find my old halogen bulb headlamp for comparison, the one that I used for years before LEDs came on the scene, but I am pretty much positive that it wasn't a patch on this, even when the brightest bulb was used (bulbs had to be manually switched to control brightness, a real pain). One of the prices paid for this intensity of light is that the lamp runs a little hot (hence the built-in heat-sink), but it hasn't felt at all uncomfortable in use. In humid summer conditions I have been able to feel the heat on my brow, something I had not noted so much in previous, cooler months. At no time was I unable to maintain the full-intensity Maxbright mode due to overheating. I mention this as the headlamp instructions state that the full-intensity Maxbright mode may be temporarily inaccessible if the lamp overheats, but so far it has shown no signs of doing so, even on the hottest of days, and even when on for hours.
I have now used the lamp with both lithium and alkaline cells. I found that performance with alkaline cells was acceptable, but that the battery life was far less than with lithium. This is as Princeton Tec indicate in the lamp's brochure. But then, the battery price is also much less, so this is a trade-off some users may decide to make. If I plan to use alkaline batteries I will always carry a spare set. The low-battery meter does provide adequate warning that power is running low when alkaline cells are used, just as l found it to do with lithium batteries. I need to be certain that if I have occasion to run the lamp on the Maxbright setting for some time, I will not subsequently be without light, hence the need to carry spares. The estimate of about one hour at full intensity on this power setting seems pretty accurate (see graph below). The mode using the four Ultrabright LEDs is better for conserving power, and is fine for most on-trail travel.
Testing power consumption and brightness
The most important part of testing a headlamp is how it performs in the field. However, as headlamp technology becomes increasingly sophisticated, some other measures of performance are useful in addition (not least because the eye is rather poor at determining relative brightness, etc.). I have previously developed a simple method for testing light output, during other headlamp tests. I have applied the same methods here.
Light output from the Apex was measured in lux, the International Standard (SI) unit of measure for luminous flux density at a surface, using an inexpensive digital light meter. A distance of two feet between the front of the lamp housing and the light meter's sensor was chosen for the test. This enabled the brightest region of the beam to coincide with the light sensor's dome. No attempt was made to keep a controlled temperature, but the ambient temperature in the room in which testing took place was relatively steady at about 75 F (24 C). Fresh alkaline AA batteries were used. I chose not to run a low-temperature test this time. I have previously demonstrated how low temperatures dramatically impact alkaline batteries (in headlamps and elsewhere). For this reason I urge the use of lithium batteries in critical equipment (GPS, headlamp, etc.) in the cold winter months.
The following graph charts the output of the Apex at the full-strength Maxbright setting, as an indication of the time that I can expect the headlamp to provide a powerful beam of light with new batteries. For interpretation, see item 1 below.
At the outset, I asked a set of questions in my
Initial Report regarding the performance of the Apex.
1. How stable over time is the light output? Does the voltage regulation circuitry indeed perform its job appropriately?
On the full power Maxbright setting, the light output is stable for many hours when lithium batteries are used (judged visually). With alkaline batteries (see graph above), the lamp exhibits significant drop-off in brightness (a bit over twenty percent) after 40 minutes. This is less than Princeton Tec's claimed time for steady power output for one hour. However, the overall level of illumination remained strong for a total of about two and a half hours, apparently held at that level by the voltage control circuitry, and taken as a whole (ignoring the initial decline, which I have noted in other voltage controlled products), this is considerably better than Princeton Tec's claim of one hour of constant burn time.
The brightness (and so, presumably, the battery voltage) then fall off fairly rapidly before starting to level off at a lower intensity. The Princeton Tec literature for the lamp claims that light is available on the full power Maxbright setting for up to 72 hours. However, it should be noted that this is light at an intensity of approximately a tenth of the initial strength, at best, as after three hours and forty minutes I measured the brightness at 288 lux. This is still adequate for many activities, including trail navigation, but based on visual observation the level dims still further after the 220 minute period I tested. Voltage control is no longer operational. For reference, from previous work I have concluded that a light intensity of about 150 lux (in this test setting) represents the lower level of useful illumination for a headlamp.
2. In each of the standard illumination modes, does the illumination pattern match the website claims? How easy to operate is mode-switching with the dual switch system that Princeton Tec has incorporated? Is the heatsink cooling of the LED adequate, or does the casing become warm (and potentially uncomfortable)? Is it adequate to protect both me and the LED?
So far as I can judge from the field, the illumination patterns (and distances) approximately match (or, in the case of the full power Maxbright setting) possibly exceed Princeton Tec's claims for the lamp. I find the dual-switch system straightforward to use. While the lamp casing can become quite warm, I have not found it to be uncomfortable on my brow, nor so hot that it's awkward to handle.
3. What are the limitations of each of the five modes, in practical terms? Which mode is optimal for trail use, which for bushwhacking, which for in-camp use? Is dazzle a serious problem in the Maxbright mode, either for others or myself? Is the flashing mode of any use?
The optimal mode for trail use depends, to a large extent, on the trail, but I have found that the full Ultrabright setting is adequate in almost every occasion, except those when I need to throw a beam of light a considerable distance. For in-camp use, the lower power Ultrabright setting suffices for many tasks, and is fine for reading. The Maxbright full power mode is perfect for travel over difficult or untracked terrain, and for guiding others, as well as incidental activities such as caving. The lower power Maxbright setting is sufficient for easier off-trail travel, or on hard stretches of trail. Dazzle is mostly a problem in the Maxbright mode, as a general rule. I have not used the flashing Ultrabright mode except once, briefly, riding my bike.
4. How effective is the LED Optic Collimator at focusing light into a beam? Is the effective range of the Maxbright on the high setting indeed "only" 56 m (184 ft)? Is the intensity of illumination within that range equivalent to daylight, as Princeton Tec claims? Is illumination reasonably even across the width of the illuminated field? How about the low setting of the Maxbright? How does that compare? What's the quality of illumination with the four Ultrabright LEDs in each setting? Is there any color cast to the light on any of the setting? If so, how does it affect perception? How focused is the Ultrabright LED beam?
The Optic Collimator, based both on the results from bench and field testing, focuses the LED well. The Maxbright LED on full power lets me see well at approximately the range Princeton Tec indicates (I base this on my cave experience in particular, where I could see fine rock detail at about the specified distance). The Collimator is designed so that much of the light is concentrated at the center of the beam, but there's enough peripheral illumination to avoid a sense of tunnel vision. The low power setting uses the same collimation mechanism. The Ultrabright LEDs at maximum setting are bright as well, and the cast of the light from these, while slightly bluer, provides reasonably accurate color perception. The Ultrabright beam is not collimated, and is certainly shorter in range, but projects an adequate distance for many uses.
5. What is the swivel range of the lamp? How comfortable is the headlamp? Is the strap system stable? Can it be dislodged by head movement? How well does it fit over a hat or helmet? How adjustable is the strap to different head sizes?
As is typical with most headlamps, swivel range is 90 degrees, from the ground to the horizontal. I prefer 180 degrees of swivel in a headlamp, but the heat shield of the Apex makes this an impossibility, and I'm more than happy to trade off the superlative brightness of the headlamp against the minor benefits of a small amount of extra maneuverability. The headlamp is comfortable for me to wear, both with and without the top strap. It fits over a hat (a Tilley) just fine, and works adequately with a bike helmet. The adjustability of the strap seems sufficient to accommodate most head sizes (I've tried it on a few folks), as well as helmets.
6. Is the lamp indeed fully waterproof? Is the battery-compartment gasket adequately attached? Can it be accidentally dislodged?
I did not have occasion to test the lamp in anything more than a very damp cave, in which it worked fine, so I can't address this issue based on my use. I will append results in future, as the opportunity arises. I have not had problems with the battery compartment gasket.
7. How easily is the battery compartment accessed? Can batteries be changed with gloved hands? How easily is the switch operated? How easy is it in gloves?
The battery compartment is easily opened, and I can change batteries even when wearing gloves, provided that the gloves are not too cumbersome. Full winter mittens make extracting and reinserting the batteries very awkward. I was able to use the switch (with some care) wearing the heaviest gloves I own.
8. Is the lamp resistant to moderate impact? How durable is it overall, during the test period?
The lamp seems very durable. I haven't handled it with kid gloves, although I've not deliberately smashed it hard into any rocks, either! It looks pretty much as new after four months of serious use.
9. How useful is the battery power meter? Will it enable me to avoid needlessly carrying spare batteries, a weight saving?
I think the battery power meter is a winner. Provided I remember to check the color of the LED (usually allowing the lamp to run for a moment beforehand), it has given me ample warning of declining battery power. When using alkaline batteries, I will certainly carry spares. When using lithiums, I will probably not if I know the set to be fresh (though I always carry a spare headlamp of some kind in any case, rendering this issue somewhat moot).
Summary
All told, I'm wowed by this headlamp. It's true it's a trifle heavier than I would normally consider carrying for solo use, or for use on a backpack with a friend, but when I consider the fact that in a true emergency I have the ability to flood the area with light, the weight seems a lot less important. I will continue to use it when leading groups, on solo trips off-trail, for long hikes on difficult terrain, or in winter. It's probably overkill for mild-weather use on trailed hikes or backpacks, but it's likely to end up being carried in any case. This is a first-rate survival tool.
