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The Princeton Tec Apex.... Looking for a great headlamp? Look no further! Princeton Tec took everything they've learned about headlamp design over the past few years, selected the best features, and put them all together into one very nice package. The Apex has four 5mm LEDs for wide angle use, a Luxeon III LED and optics for spotting, and both have two available levels of output. The 5mm LEDs can be set to a beacon blinking mode as well. The unit runs on 4 AA batteries which can be alkaline, NiMH, NiCad or Lithium 1.5V. It has a removable top strap, a LED battery level indicator, two separate switches for the lighting elements, and a large aluminum heatsink to protect the LEDs from damage.

Body: The "body" of the headlamp includes the front lighting element, the rear battery box, and a 3-point removable elastic headstrap system. The top strap is completely removable if you choose not to use it. The rear of the lighting element forehead plate is perforated plastic and is quite comfortable. At the rear, the battery box has rubber cushions that provide a comfortable platform at the back of the head. Two clips hold the wire to the straps on the user's right side. The straps are fully adjustable. The entire unit is available in Olive Drab (shown), Orange, or Black.

Bezel/Head: The head is where all the "magic" happens. You will find a Luxeon LED in the center, flanked by two 5mm LEDs on each side. Both the Luxeon optics and the 5mm LEDs are protected by clear plastic lenses. Despite warnings in the instructions against opening the unit, I found it was very easy to do so. Actually I felt compelled to open it up since one of the 5mm LEDs was severely off center. This was extremely easy to correct once the unit was open.

Just below the Luxeon LED is what appears to be a little hole in the bezel. This is actually the battery level indicator LED. It lights green when there is >40% power left in the cells, turns yellow when there is less than 40% left, and turns red when there is about 20 minutes of power left. When it turns red the main LEDs will blink 3 times to give you a visual warning as well. When the headlamp is turned off the battery power indicator will blink on and off for 24 hours to serve as a "find-me" indicator, and then it will turn off to conserve power.

Behind the LEDs is a regulator circuit to provide fairly constant output from the LEDs, and in the very back of the head is an aluminum heatsink that draws heat away from the LEDs, allowing them to run at higher output levels than would normally be possible in a sealed plastic headlamp. The heatsink is protected from damage and accidental user contact by a plastic framework.

At the bottom of the head are the two independent switches for the 5mm LEDs and the Luxeon. The entire lighting element system is attached to the headstraps by a smooth 90 deg. Adjustable hinge connected to a forehead plate. Hinge tension can be adjusted with a screwdriver and a small wrench.

Output: With the PT Apex, you have two (well actually, five) output options. Each of the LED lighting elements are controlled with a separate switch. If you have one of the lighting elements already on and you select the other switch, it turns off the former so you cannot have both the Luxeon and the 5mm LEDs on at the same time. Clicking the Luxeon switch turns the LED on high, a second click selects low. Same for the 5mm LEDs, but a third press switches to a blink mode. Repeated pressing of the switches causes the cycles to repeat. Turning the headlamp off is accomplished by holding the switch down for 1 second.

The Luxeon LED produces a round spot of light with some very slight rings. Good for distance spotting. The 5mm LEDs produce a wide flood of light in the direction pointed. Good for close range work.

The white light produced by the 5mm LEDs is a high color temperature and produces good color rendition weighted toward the blue end of the spectrum. A slight bluish tint is detectable when compared against a near sunlight-white source. The white light produced by the Luxeon LED is a medium color temperature and produces good color rendition overall. No significant tinting is detectable.

   
Beam at one meter at target center; Luxeon, 5mm LEDs.

Runtime Plot: Plot of Luxeon III output on High using alkaline cells. Very nice! Regulated runtime was indeed what the manufacturer indicated with alkaline cells - 1 hour. At that point the regulation begins to fail and at 1 hr 44 minutes the headlamp switches to direct drive from the batteries which provides a lower, declining, output for a long period of time.

Runtime completed with Duracell brand batteries. More information on runtime plots is available HERE.

Switch: The two switches are on the bottom of the head. Can you guess which switch controls the 4 LEDs and which controls the one Luxeon LED? I'll bet you can! The switches were obviously designed for quick tactile identification by employing textured patterns on the switch covers.

When activated the switches provide a nearly silent click. If either LED element is selected and you press the other switch, the first selection turns off in favor of the new selection. Therefore you cannot run all of the LEDs at once. You can only have the 4 LEDs or the Luxeon LED on at any one time. A press and hold turns the unit off, while rapid clicks change output settings.

Seals / Water Resistance: Princeton Tec gives the unit a 1 meter submersion rating. This translates to "dunkable" by my ratings. Everything does appear to be well sealed. Be careful when you open the battery box - the first time I did the seal jumped out of its groove and had to be tucked back in.

If it gets wet inside, just disassemble as much a possible without tools and let it dry before using again.

Ergonomics: Here it is shown without the removable full-size top strap, but you'll probably need it because the 4 AA cells in the back do get fairly heavy and the extra support is welcome. I'm very glad they included a FULL size strap for the top. A rubberized cushion at the back provides comfort for the battery box area and the well designed forehead plate results in no pressure points at the front of the head.

Batteries: Four AA alkaline, NiMH, NiCad or Lithium 1.5V batteries can power the headlamp. Lithium 1.5V AA cells provide the longest runtime (and best cold-resistance), while rechargeables may run the headlamp at slightly lower output levels.

To change out the batteries you must open the slide-out battery drawer. The drawer is locked in place by a cam at the bottom of the battery box. In case you can't quite grip it with your fingers to turn the cam, you can use the tab on the headstrap adjuster or a coin to twist the cam 1/4 turn.

Once the drawer is unlocked, slide it up and out. Put in new cells while observing proper polarity.

Close the drawer tightly and twist the cam back to its locked position.

Accessories: Batteries and the removable top strap are included with the light.

What I Liked: Waterproof, Tough/impact resistant, Regulated/long battery life, Bright, Easy battery change, Battery life indicator, Very comfortable on the head.

What I Didn't Like: Not a darn thing.

Picky Little Things: As mentioned, one of the 5mm LEDs was badly off center, but I found that the unit was easy to open and (carefully!) make a corrective adjustment. Be aware that opening the unit voids the warranty.

Conclusions: 5 Stars! Top rating. What else needs to be said? Possibly the perfect all-around headlamp.

UPDATE, Aug 2006: Spoke too soon? Two reports of problems with the Apex have reached me. First is due to the fact that there is a gap in the headband retainers. This gap is designed to make it easy to remove the headband for cleaning or replacing, but apparently it also can allow the headband to slip out of the loops when stretched tightly, such as over a helmet. Be careful you don't lose your light! The second problem reported was two units used by spelunkers in Australia that had to be returned due to water entry after receiving a dunk. Not good. I'll do some more research into these issues.

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