Princeton Tec Corona Headlamp.
Straight from the more-is-better school of headlamp design, the Princeton Tec Corona impresses with an eight-LED array powered by three AA batteries. The Corona is of primary interest to hikers and campers who want an efficient floodlight-style LED headlamp that also supports semi-technical nighttime navigation. There are lighter headlamps and there are brighter headlamps, but the Corona is versatile and easy-to-use. In an effort to please all users in all situations, the half-pound Corona offers myriad settings, twelve in all. If nothing else, this gives Corona owners ample opportunities for button pushing.
|Separate lamphead and battery pack, cable-connected|
|Eight 5 mm white LEDs arranged in three rows|
Manufacturer's Run Times
|30 to 70 hours, highest and lowest continuous modes|
Modes and Settings
|Four operating modes, each with two brightness levels and one strobe setting (approx 100/min) for twelve total|
|Lamphead fitted with aluminum heatsink|
|Uses three AA alkaline (provided), lithium or rechargeable cells optional (the last at reduced output)|
|Backpacking Light measured: 7.9 oz (226 g) with alkaline cells, 5.3 oz (152 g) without batteries. Manufacturer: 8 oz (227 g) with alkaline batteries.|
|Double strap bucket-style, adjustable-length elastic, removable bands|
|Hinged, gasketed battery cover locks with flip latch|
- Twelve settings
- Current regulation
- Rear-mounted battery box for balance, keeping batteries warm under a hood
What's Not So Good
- Relatively heavy
- Not as bright as the 1-watt competition
- Current regulation only partially effective
The Corona's lamphead arranges eight 5 millimeter white LEDs in horizontal rows of three (top), four (center) and one (bottom). There are two switches: the larger main switch controls the LED array in a four-mode sequence and the smaller, nubbed switch rolls through three level settings within each mode. The switches are top-mounted on the lamphead, beside one another and sit in shallow recesses that help prevent accidental use.
The LEDs sit in a silvery reflective base protected by a clear convex plastic lens, itself protected by a surrounding bezel. The silver-painted LED base is contoured somewhat, probably to differentiate the LED groupings' respective beam patterns. (Because the Corona's LEDs aren't a side-firing type, there's not much stray light to be gathered and aimed by a reflector.) The rear of the hinged lamphead sports an aluminum heat sink set behind a plastic shield. The heat sink cools the electronics (LEDs emit heat and as I discovered, eight emit quite a bit). Three AA batteries reside in a gasket-sealed battery case that's attached to the back of the head strap and connected to the lamphead with a power cable. A flip latch locks the hinged battery case closed. The adjustable-length bucket-style headstrap (a main strap and a top strap) are long enough to fit over a helmet.
Materials and Construction
The Corona lamphead shell and battery box are made of hard, high-impact plastic. The curved battery box more or less fits the head's contours, but there is no padding other than the headstrap itself. This is quite evident reading whilst lying on one's back. The elastic headstraps are soft and comfortable, and offer a wide adjustment range. The 4 millimeter thick power cable has a substantial rubber jacket and is reinforced where it enters the battery box to prevent pulling out. Two quick-disconnect clips attach the cable to the headstrap on the right side.
The larger power/mode switch and smaller setting switch are easy to find and differentiate by touch. I can operate both switches while wearing thin gloves, even some mittens. Operation is as follows:
- Main switch (large, smooth button on the right-hand side) - Mode 1 (eight LEDs), Mode 2 (five LEDs), Mode 3 (three LEDs), Mode 4 (one LED), off. A five-second pause in any mode keeps it in that mode, with the next button press switching the light off.
- Level switch (smaller nubbed button on the left-hand side) - high, low, blink, repeat... The cycle repeats no matter how long the light has been switched on.
- The Corona has no last-use memory and always switches on to Mode 1, high.
The lamphead can be tilted downward but not higher than straight ahead, somewhat of a limitation for overhead work (stringing a bear line, for example). The hinge can be tightened or loosened with a Phillips-head screwdriver. Adequately tightened, it holds its position during high-impact activities - inadvertent droop is not a problem.
The battery case latch is quite stiff and a challenge to open with cold hands or while wearing gloves, when I find it's much easier to pry the latch open with a lever (e.g. spoon handle, screwdriver). Correct battery alignment is easy to make out even in poor light, and the batteries remain in place until pried out.
The slotted lamphead and battery case strap guides allow the straps to be completely removed or replaced in seconds. This enables use of the light either without the top strap or with no strap, and the straps can be washed or replaced.
Regardless of the mode or setting, the Corona's beam always displays a bright center spot having a noticeable purple tint, and surrounded by a cold white halo. Switching among the four modes, the center spot and halo change in size and intensity but retain this basic configuration, which is very typical of flashlights using standard 5 millimeter white LEDs. Our light meter showed the beam intensity to be rather irregular and more varied than the eye can easily detect. All but the single-LED mode project a roughly oval beam, wider than it is high, with the three-LED mode perhaps the most pronounced.
Taken from the dimmest mode to the brightest: Mode 4, single-LED is an adequate camp and reading light, even on low. It, of course, has the narrowest beam angle and smallest center hot spot, so while it dazzles the eye the least, it also offers the narrowest floodlight. It's possible to operate an entire evening in camp using Mode 4-low, provided there are no challenging chores like stringing a food bag line or pitching a tarp. The benefits of doing so are the greatest battery life and preserving night vision. Mode 3 (three LEDs) offers a significantly wider beam angle, easing performing chores and supporting walking on clear trails. Mode 3 has an ovoid center spot and floodlight halo, the result of the three LEDs being in a row and surrounded by their own mini-reflector.
Modes 2 and 1 (five and eight LEDs, respectively) are similar to one another in beam configuration, differing mainly in their intensity. Even in Mode 1 there is no sharp center spot such as with the 1-watt collimated LED used in the Princeton Tec EOS or Black Diamond Zenix series, but the surrounding floodlight is much broader and brighter than those headlamps. It's still possible to perform fairly complex nighttime navigation with the Corona, so it might warrant consideration by climbers and cross-country buffs, but the 1-watt lamps throw an effective beam much farther and illuminate objects and the trail with far greater detail. The Corona's heft makes it less than ideal as a running light but at least with a rear-mounted battery box, it is well balanced.
The strobe feature seems most useful for marking a position to which one wants to return, such as a sleeping site some distance from main camp. Aimed at a tent canopy or tarp, the flashing makes it easy to spot a shelter from a good distance while off stargazing or initiating the nitrogen cycle, and it's likely the Corona's most frugal setting. I don't discount the potential for using the flash as an emergency signal should the need ever arise. Mode 1 maximizes the angle from which the light can be spotted from afar.
The Corona is at a minimum water-resistant and should shrug off rain with no problem. Our dunk test (brief immersion in water a few inches deep) showed a few droplets made it past the battery box gasket, notably at the point of small imperfections. The battery box can be rinsed out should it come in contact with saltwater or if batteries leak, but the lamphead resisted our attempts to open it up. This means that should moisture ever invade the lamphead, where all the electronics reside, it might not be possible to dry it out.
The test Corona is made of gray and chartreuse plastic and sports a gray and black elastic headband. The bright color is welcome for making the Corona easier to find in dim light or sitting on the ground in forest clutter. It's all too easy to misplace a black, gray or silver flashlight and leave it behind when packing, but that doesn't stop makers from frequently using those hard-to-see non-colors.
In the Lab
I measured the Corona's beam intensity in the mode and level combinations, both in the beam center and 1 foot off-axis. The following table gives the results.
|Mode 1 (eight LEDs)||Mode 2 (five LEDs)||Mode 3 (three LEDs)||Mode 4 (one LED)|
|Setting||Beam center||1 ft off-center||Beam center||1 ft off-center||Beam center||1 ft off-center||Beam center||1 ft off-center|
|*Highest continuous recordable readings|
Much like a bicycle with thirty possible gearing combinations yields perhaps two-thirds as many on the road, not all of the Corona's eight (twelve if you include flash) mode and level combinations are useful. That said, because the beam pattern changes with each of the four modes, no two appear exactly alike even if the measured intensity is similar; also as batteries wear, an unused mode and level can become "just right." (Because we don't have the complex instrumentation required to measure total light output we can't say, for example, whether Mode 1 low might put out more total light than Mode 2 high, even though the latter is demonstrably brighter at the beam center.)
We chose two modes to test battery life: Mode 1-high and Mode 3-high (eight and three LEDs, respectively). The first is a measure of what the Corona will do "maxed-out," the second a measure of what we felt to be the most reasonable setting for all-around general use - giving both adequate light with long battery life.
Interpreting the Results
Despite the Corona's claimed current regulation, it exhibits time-output curves typical of lights without: there's a nearly continuous drop in output over time. In our tests though, the Mode 3 (three LED) drop was much less precipitous than that of Mode 1 and in practice is not particularly noticeable for a good many hours. Mode 1 output plunged from the start and the dimming was noticeable. The Corona circuitry does seem effective at extending the "toe" of the output curve by coaxing the last bit of juice from the batteries, albeit at dim levels. We didn't try to establish the runtimes to the last eventual wink-off. It will likely occur days past where our chart extends. At below 50-lux levels, light is sufficient for digging items out of backpacks, simple camp chores and clear trail-walking for those possessing owl-like night vision. Glacier travel, not advised.
Nighttime maneuvers are easily performed via the Corona, and camp chores are a snap because of the generous beam width. The amount of light it puts out is really quite impressive and the lower modes are adequate for everything short of tricky navigation and poor trails. Map reading and bedtime reading aren't difficult, despite the somewhat distracting purplish beam-center blob. I found the multi-LED modes in low to be better than the single-LED mode for reading.
There are, however, tangible differences between multi-LED arrays such as the Corona's and a collimated 1-watt LED that hydra-head designs can't overcome when the going gets technical. Even with fresh batteries, maximum Corona output is roughly half as bright as Princeton Tec's own EOS and its 1-watt Luxeon. Compared with the EOS, the Corona's beam is more of a floodlight, covering considerably more area but not projecting as far. Details such as uneven surfaces aren't as distinct and there's more backscatter (glare) in rain and fog. Which type of light is better, depends both on conditions and your intended use.
Because the Corona always switches on to eight-high mode, users concerned with preserving their night vision should cover the lens until they progress to the desired lower level. For example, selecting Mode 4-low - the dimmest setting - takes a total of five button presses.
We also discovered we can remove the top strap and battery pack and still wear the lamphead using just the main strap. Although the short cable prevents placing the battery pack in a warm pocket, we can keep it warm under a turtleneck or even perched on a shoulder. Not an elegant or the most comfortable solution for keeping the batteries warm but effective, not to mention the lamp is noticeably lighter on the head and the strap can be worn looser. In more prosaic pursuits, with the battery pack detached the Corona is far more comfortable for reading in bed.
The Corona would be improved with more effective current management and a memory that retains the last setting used when it's switched on. Substituting a red LED for part of the lamphead array would offer a night-vision preservation mode, a mode that would be best if it could be accessed directly from off, perhaps through a separate switch.
The Corona's design concept has been trumped by newer 1-watt headlamps for non-technical use, especially those that either combine the main LED with one or more 5 millimeter LEDs or provide a flip-down diffuser lens-. As our tests demonstrate, even eight 5 millimeter LEDs can't begin to match the output of a single 1-watt Luxeon. The Corona is both versatile and frugal, provided the many modes are used judiciously, and the light from its massively parallel LED array is good enough to support general backcountry activities and is especially nice for in-camp chores, where a flood-style beam is appreciated. But at eight ounces, the Corona is very heavy for a headlamp that doesn't offer a long-throw pencil-style high beam suitable for technical nighttime activities, such as climbing and off-trail travel. For these pursuits there are better lights, including other offerings from Princeton Tec.