Princeton Tec Impact

Princeton Tec 'Impact', retail $29.95
Manufactured by Princeton Tec (
Last updated 08-24-06

LED Light

The new Impact by Princeton Tec is the cousin to their Attitude, also a new product.
A single white LED is housed behind a specially designed precision lens, which allows the Impact to project a beam up to 150 feet away. The light is made of a sturdy Xenoy plastic, and uses 4 common "AA" cells to power the LED for 150 hours or more.
It comes in black and in a fluorescent day-glow green, which might be preferable if you tend to lose a lot of flashlights in the woods.

Size reference

The Impact comes with a set of 4 Duracells (not installed, for freshness) and a lanyard attachment.
Feed the lanyard through the hole on the end of the flashlight with a small screwdriver, broken-off toothpick, or similarly-sized instrument. Then install the batteries.

Once you have the batteries in, twist the bezel (head) clockwise to turn it on, and turn it counterclockwise to turn it off.

[image 4 AA cells]
Unlike most small, cylindrical cell LED lights that run from 3 cells, the Impact uses 4 "AA" cells arranged so that there are two cells on each side. This keeps the length of the unit down so it stores and handles a bit more easily.

To install the batteries, place two cells in one chamber, both facing the same direction. Then fill the other chamber but install the cells the opposite way. There are polarity markings (+) and (-) inside the light body so you know which way to aim the batteries in each cell. Unlike the Attitude, you must follow these markings because the reflector head only fits one way. On the bottom of the LED module, you will find (+) and (-) markings near the contacts. Place the module in the light body with the (+) contact nearest the (+) battery nipple, and screw the black bezel down.

The Impact is another example of Princeton Tec's good workmanship. The body is composed of tough GE Xenoy thermoplastic, and handles everyday bumps and bruises just fine. First drop tests do show that the Impact is loud when it smacks into the ground, but so far, that's all.

Striking the barrel of the light hard against the test rod (a pair of 3' L x 1" Dia. bars of par steel, firmly affixed to a table) five consecutive times in the same place right near the seam also failed to do any harm.

Crushing it under the wheels of a heavy motorized chair didn't phase it.

The bezel assembly is covered in a semi-hard rubber that has a series of long, oval shaped "bumps" to provide some extra grip for turning it on and off. The lens is recessed slightly, so it won't become scratched when you set the light face-down. The rubber also cushions the polycarbonate lens & bezel, effectively making it as tough as the rest of the flashlight.

The Impact is rated submersible to 500 feet, though at present I can only test to around 2 feet. :-O
It is sealed by an O-ring that will need occasional attention. Every once in awhile, clean the O-ring and threads, and lube it with silicone grease. The instructions explicitly forbid the use of any aerosol lube, so you'll need the stuff in the tube which can be found at any diver's shop or at some electronics outlets like Radio Shack.
If you use this light outdoors a lot, it's a good idea to clean it off in fresh water every day, and check the O-ring for dirt, cleaning & lubing it when necessary.

A platinum catalyst pellet is supposed to be in there somewhere (they are put in sealed, watertight flashlights to absorb hydrogen from the batteries), but I did not hear or see it in the test unit. It is most likely inside the multipart reflector/lens assembly.

The Impact has a specially designed lens to grab and focus the light from a single white Nichia LED and project it up to 150 feet away. This is in stark contrast with most other LED lights who's beams peter out anywhere from 10 to 40 feet away.
This lens is unusually high in quality considering it is in a plastic flashlight. As an informal test (as I am *not* an optician!), I took the lens off the Impact and put it on my camera, and then took pictures of a couple of loose LEDs on my computer's wrist rest pad. No setup, no tripod, just quick snapshots. And yet they actually came out.

LED Light
I also tested the lens with a laser, and found virtually no visible optical defects. The depth of field is a bit shallow for this type of use, so the edges are a bit fuzzy. But it wasn't meant for this purpose; I simply did it to demonstrate the quality of the lens.

LED Light
Brightness measured at 72,600mcd within the narrower than usual beam.
Compared with the flashlight with the most similar beam - the Brinkmann Long Life LED.

The flashlight comes in two colors: black with white logo, and fluorescent yellow-green with black logo. If you tend to lose a lot of flashlights because they fall into bushes and disappear, the day-glow green will make the Impact easier to find, even if it's night and you're using another flashlight to look for your flashlight. It is also easy to spot inside your backpack or camping bag, or anywhere else you might happen to store it.

Like the Princeton Tec Attitude, the Impact also had a tonal, hollow noise when smacked while empty. Yet once you load batteries in, it magically transformed into a sturdy, robust instrument.

LED Light
Comparison of the "waste light" (corona) between the Brinkmann and the Impact. Notice the Impact has a wider, cleaner corona, making it a bit more suitable to use for walking around. You need some of this "waste light" or else the unit wouldn't be very usable except for long-range illumination.

Light distribution curve of the Impact at 3 feet.

Beam profile analysis, illuminance values at 3 feet.

Isometric beam profile analyzis - a 3-D look at the Impact's light distribution pattern.
This data made by the ProMetric System, on loan from Radiant Imaging.

Spectrographic plot
Spectrometer plot of the LED in this flashlight.
Ocean Optics USB2000 Spectrometer on loan from TWO-CUBED.

UPDATE 09-25-01:
Evaluation unit was received this afternoon. Testing is concurrent with several other flashlights, and won't be finished "overnight".
Thanks again to D. Cozzone of Princeton Tec for the sample.

UPDATE 09-26-01:
Unit was turned on and left in the rat bathtub - er - the sink for approximately three hours. As expected, it was still bone dry inside.

UPDATE 09-27-01:
After a fairly harsh dose of abuse, the catalyst pellet can now be heard rattling around inside the head, in much the same manner as the pellet in the Attitude. This will do absolutely no harm, and won't adversely affect the functionality of the Impact. You may hear a slight ticking/rattling type sound when the Impact is shaken. This can be ignored. In a second sample of the Impact, this sound could be heard right away, with no abuse necessary. What has probably occurred is that the pellet became wedged someplace in the first sample before I received it and therefore I did not hear it rattle. Smacking the flashlight simply dislodged it from that location. It is still contained within the reflector assembly, free to do its job.

UPDATE 11-07-01:
As you can see, this is the first light to have been run through the ProMetric System. Since this is my first experience with this equipment, some of the photometric values could be off by a few percent, but the actual images and plots are accurate.

Durable, tough housing
Bright, for a single 5mm LED
Uses inexpensive, readily available batteries

No spill light might not be suitable for some users

    MANUFACTURER: Princeton Tec
    PRODUCT TYPE: Small handheld flashlight
    LAMP TYPE: White LED
    No. OF LAMPS: 1
    BEAM TYPE: Circular, focused with little spill light
    SWITCH TYPE: Twist bezel on/off
    BEZEL: Acrylic lens with LED behind it
    BATTERY: 4x AA cells
    CURRENT CONSUMPTION: Unknown/unable to measure
    SUBMERSIBLE: Yes, to 500 feet
    ACCESSORIES: 4x AA cells, split ring
    WARRANTY: Lifetime


    Star Rating

Princeton Tec Impact *

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