LIGHT CANNON 100, retail $150-$175 (
Manufactured by Underwater Kinetics (
Updated 04-21-11

Light Cannon

It's not incandescent. It's not fluorescent. It's not electroluminescent. And it's most definitely not LED. So what is it doing on The LED (and Laser) Museum?
Because The LED (and Laser) Museum has grown to become more than just LEDs. Just look at the incandescent flashlight section for evidence of that. Sure, it's starting out small, but so did the original LED flashlight section.

The new Light Cannon 100 is based on HID technology. HID stands for High Intensity Discharge, and the most common example would be those brilliant blue-white headlights showing up on expensive cars like those made by BMW and Mercedes. Instead of a hot metal filament or a glowing block of chemicals on a stick, HID lights create light using a tiny ball of superheated, electrically-charged plasma inside a small quartz bulb. The result is light that is brighter and whiter than incandescent, and with more spectral content than LEDs.

The large light is powered by 8 C cells, and is made of tough ABS and rubber.


To use the Light Cannon, pull out on the locking switch, and turn it counterclockwise about 1/8 of a turn. The light will start out blue and very dim, but it brightens up to full power over the next 20 seconds or so. To turn it off, turn the locking switch the other way (clockwise). Push it flush against the ribbed locking post to lock it in the "off" position and prevent accidental activation.

If you turn the light off and then immediately find you need it back on, you need to wait in the dark for 3 seconds before you can restart the HID bulb. This is printed on the butt of the Light Cannon in case you forget, along with the note that it takes 20 seconds to reach full power. Just in case you forget and think it's an incandescent or LED - but it's hard to forget it's HID once you see it fire up for the very first time.

NOTE: It is *normal* to see the light emit bright flashes of red or orange when it is warming up. These flashes of color are thought to be caused by tiny grains of sodium iodide falling onto the electrode tips or being sucked into the arc and then vaporising. They should be considered harmless and quite normal.

The model I'm using came with a pistol grip handle; just slide it onto the dovetail fitting found on both sides of the body, and tighten the screw by putting your screwdriver through the hollow base of the pistol handle. Test the handle to be sure it won't slide off before you try to pick up or use the light with the handle. If the handle slides, you need to tighten the screw a little more.
A brightly colored, padded lanyard with a sturdy locking mechanism easily attaches to the handle using the large opening provided for it.

The Light Cannon also comes with a pair of diffusing filters to broaden the beam to a medium or wide flood, depending on if you use just one filter or if you put them both in at once.
To install the filters, just unscrew the rubberized bezel, lay one or both filters on top of the reflector, and screw the bezel back on. They will widen and diffuse the Light Cannon's beam to allow it to be used as a video light.

Got Bulb?
Got $80?
That's what it'll cost you if you break the light bulb. The bulb will normally last around 1,000 hours, which is a really long time for a flashlight or other handheld light source. This should equate to at least a couple to a few years of regular use (a couple of times a week for an hour or two at a time) before you had to spring for the $80 replacement lamp.

But if you do need to relamp the Light Cannon, here's how you do it:
  • If the Light Cannon was recently used, allow the bulb to cool before opening it up.
  • Unscrew the rubberized end cap.
  • Remove the reflector.
  • Pull the old lamp straight out.
  • Align the two pins on the new lamp with the holes provided for them. Be sure the alignment rib on the side of the lamp base is aimed toward the notch for it in the socket. Then gently push the new bulb straight in until it stops.
  • Finally, lay the reflector back onto the lamp module, and screw the rubberized bezel back onto the body of the light until it's firmly on.

    If you install the bulb backwards, it will burn out *very quickly*, so you must take care to insert it the correct way!

[image 8x C cell]
First things first: You'll want to install a really big garbage can in your flashlight room, because you'll be throwing out 8 large C cells at once.

To get it on... unscrew & remove the rubberized bezel, and remove the reflector & lamp module. Then remove the dead batteries and sh**can them. A plastic & metal plate with springs on it will probably also fall out. First thing you want to do is put this back in. Embossed on the top of the plate (the side without the springs) are the words "ALIGN HERE ==>" with the arrow. Place the plate in the light, springs down, and align the "ALIGN HERE ===>" with the sticker inside the flashlight body with the same text on it. Then simply let it drop into place when you can't lower it any farther by hand.

Install 4 of your new alkaline C cells so the flat (-) side goes on the part of the plate with the doughnut-shaped contacts, and install the other four with the button (+) side going in first. There are no (+) and (-) markings inside. If you're now thoroughly confused, you will want to get the instruction pamphlet that came with your Light Cannon and use that as a guide. If you are now sitting here with all your batteries loaded and wondering what to do next, hold the now-loaded Light Cannon upright (you don't want to dump out all those batteries you just put in!) with the switch facing your chest, and place the lamp module in so that the Cherry switch on its side also faces your chest. It should slide right in at this point. If it's in right, it won't turn when you try to rotate it. Screw the rubberized bezel back on, being sure to tighten it enough to compress the O-ring so the Light Cannon won't spring a leak.

Battery life is estimated at 4 hours; this will of course have to be tested.

The body of the Light Cannon is made from a thick ABS plastic, and is as tough (or tougher) than anything out there. However, because the lamp itself is quite fragile, you shouldn't drop your Light Cannon or use it as an impromptu hammer for smashing open old toilet tanks.
Use a real hammer to do that. ;-)

The Light Cannon is dive-rated to 500 feet, and it should go that far if you clean & take care of the O-ring as directed in the owner's pamphlet. It can be used both underwater and on land. When used on land, pay no attention to the weather, because the Light Cannon doesn't give a rat's patootie about either a little rain or a big flood. It would also be at home around swimming pools, lakes, and ponds. Go ahead, dunk it and check out those cool looking dragonfly larvae & waterbugs in a pond or lake near you.

Despite having all those heavy batteries in it, there is absolutely no rattle when the light is shaken or manhandled. It feels very solid in the hand. But, the Light Cannon has a dark side to it. If you drop it, there's a pretty fair chance you'll be out an $80 bulb!! Unfortunately, miniature HID lamp technology is still rather fragile and delicate, and a fall from as little as 3 feet can cause lamp breakage. :(

Because I can't afford to replace the bulb if I break it, this is one light I will not be drop-testing. That will have to be left up to a laboratory, agency, or person with deeper pockets. Remember, I'm a hobbyist living on a small disability stipend, not a large organisation with lots of outside funding at my fingertips, like... oh... Underwriters Laboratories or Consumer Reports. :-O

If you take the light module out and remove the two screws on the base, you'll see a few goodies inside. First off you'll see the ends of two fuses. One is the fuse in the circuit itself, the other is a spare in a holder made for it. The other thing you'll see is a small chamber filled with those platinum catalyst pellets. The pellets are loose in this chamber, so they're easy to replace if the need should arise. The base you unscrew to get to the fuses & pellets actually acts like a lid and holds them in place.

Fuses & stuff
Light module open to show main & spare fuses and a bunch
of catalyst pellets in a chamber where they're easy to change.

Light Cannon
This is the Light Cannon going up against the next brightest light I could find: a PT Surge. The lamp is a Welch-Allyn 10 watt "Solarc" High Intensity Discharge, pulse-type trigger start. The 10 watt metal halide lamp outputs at least as much as a 20-25 watt halogen incandescent.
Measures 1,850cd (1,850,000mcd) on a Meterman LM631 light meter.

Light Cannon
Comparing the Light Cannon and the Surge against a door from 11 feet away.

Spectrographic plot
Spectrum of the HID lamp in this flashlight, normal.

Spectrographic plot
Spectrum of the HID lamp in this flashlight, overdone to show weaker spectral lines.

Spectrographic plot
Same as above; newer spectrometer software & settings used.

Spectrographic plot
Spectrographic analysis of the HID lamp in this flashlight, after ~50 sec. warmup; newer spectrometer software & settings used.

Spectrographic analysis
Spectrographic analysis of the HID lamp in this flashlight at fire-up; newer spectrometer software & settings used.

Spectrographic analysis
Spectrographic analysis of the HID lamp in this flashlight ~75 seconds after warmup; newer spectrometer software & settings used.
USB2000 Spectrometer graciously donated by P.L.

A video of this light and the SureFire G2 CPF-50 flashlights attempting to nock the Syma S107G R/C Coaxial Helicopter out of the air.
You can guess who wins...if you guessed "the flashlights" then WRONG SOONG! WRONG SOONG!! {from the Star Trek: TNG episode "Brothers} mean, "You guessed incorrectly!"
Even with intense light (both from incandescent and HID sources) falling directly onto the heli's sensor, nothing at all unfortunate happened to it!

I thought that the HID light would have brought the heli down, but examination of its spectrum showed relative lack of NIR (near-infrared) spectral lines -- the part of the spectrum that the heli's Rx would be most sensitive to after seeing it not come down when irradiated with powerful lasers and other visible light sources.

This video is approximately 2.60226568590 megabytes (2,778,433 bytes) in length; dial-up users please be aware.
It will take no less than twelve minutes to load at 48.0Kbps.

Test sample was purchased with my own funds, and there wasn't enough to get a spare $80 bulb. Thrash-testing won't be done if or until I get a spare lamp for it.

UPDATE 01-04-02:
Measurements have been taken using the ProMetric system.

If you get tired of that, here,'s a close-up of the bulb. :-)

The orange spots on the inside of the bulb are composed primarily of thallium iodide; and the round globs on the ends of the electrodes are composed primarily of elemental mercury. These are quickly evaporated and incorporated into the arc soon after the lamp is turned on. These are two of the compounds inside the bulb which make it a true metal halide lamp; albiet a *very small* one. That globe with the orange stuff in it is about 1/3 to perhaps 1/2 the size of a common BB, and the light emitting region is half the size of that even. The tiny space between the two electrodes is where all the light comes from.

Note the way the poor Light Cannon was cruelly affixed to the test set for ProMetric testing. :-(

Cross-sectional analysis.

Beam contour (isometric) analysis.

Data provided by the ProMetric System, on loan from Radiant Imaging.

UPDATE 01-26-02:
I finally went through a set of batteries. I estimate I got about 3 hours out of them, with the last two hours of use occurring only after the batteries had been pre-chilled to a temperature in the middle 30s. Last usage was during a rare Seattle snowstorm, and it did well until the batteries finally started to crap out. When I used it today to light up my snowy trip home, I noticed it was dimmer than usual after having been on for about ten minutes - not surprising considering the already well-used batteries were sitting at near freezing for the previous five hours I waited in an outdoor line for Mariners tickets. I turned it on when I left Safeco Field, and it stayed on as I did doughnuts in several locations on the way home. The Light Cannon went out after I skidded into a pole. When I restarted it, it took forever to come to brightness, and eventually only made it to about 60-70% of its "new" intensity, but it did stay on for the last 45-50 minutes of my trip including a bumpy ride over train tracks and some ripped-up brick pavement. Remember, the light is mounted to my wheelchair in a location that has no shock absorption.

I put new batteries in, then noticed a film on the reflector (I noticed it when I first got the LC, but ignored it). I took the reflector & bulb out and the film cleaned off with nothing more than a paper towel, but when I reassembled the light, it wouldn't light. I tried re-doing the batteries, re-seating the bulb, changing the fuse, and finally, connecting the head directly to a 12V lab supply.
Snapsnapsnapsnapsnap. A small dim spark shoots across the bulb's internal contacts for about half a second (this is the starting pulse train), but the bulb didn't start. Again. Snapsnapsnapsnapsnap. Still nothing. Took the bulb out, examined it, and reinstalled it. There it goes - it lit. Put the assembly back in the flashlight, and nothing.
Played "musical batteries", still nothing. Took the head off, examined it again, and screwed it back on. There it goes... bright as new! It's working fine now, and it's back to "like new" intensity and it starts every time, but I still have no clue as to why it was being all pissy and refusing to work before. It could be something as simple as short nipples on the batteries - I used Radio Shack alkalines because I got them free. :) I'll try Duracells the next time I need to change them, and see if I still have problems.

The Light Cannon 100 used as a headlamp for an electric wheelchair.
As of 06-07-04, it's still there.

UPDATE 01-22-05:
A few days ago, I was driving down my street in my electric wheelchair, with the Light Cannon turned on. A man in a truck going the other way stopped by me and said "Nice light! I saw that thing all the way down the street!". And this morning, I was just leaving the Safeway at 87th and Greenwood and a man said "Nice light!" as I went by.
I realise this update has nothing to do with the operation of the light itself, but it seemed noteworthy in any case.

UPDATE 02-12-05:
I found this photograph of the Light Cannon's bulb by itself, and decided it belonged on this web page.

UPDATE 06-23-05:
A fan of the website emailed me and furnished {link removed} where you can purchase replacement bulbs for the Light Cannon for $60.99 instead of the usual $80.00.
Thank you for finding that!!!

UPDATE 08-27-05:
I heard from another Light Cannon owner that spare bulbs can be had for $69.00 and recharger kits are available at, a (the) major retailer for the Light Cannon.

UPDATE 06-02-06:
A person emailed me asking about the purpose of the catalyst pellets in this flashlight, and this is the answer I furnished:

Alkaline batteries vent (give off) hydrogen gas when they're under significant discharge like they are in this flashlight. This gas can cause significant pressure buildup inside well-sealed lights; which can lead to an explosion or a rupture, leaving the light with no more water-resistance - not a good thing to happen with a dive light. These platinum catalyst pellets are designed to absorb the hydrogen gas so the flashlight does not end its life with a bang like an M-80 blowing up a porta-potty; possibly causing injury to the user in the process. :-)

UPDATE 06-02-06:
You'll never guess what I found last night while looking for something else in the boxes the movers delivered to my new home in Sacramento...the diffusing lens filters!!! I thought I'd lost them in early-2002!!!

UPDATE 02-08-07:

I mounted the Light Cannon to my new (06-12-06) electric scooter a couple of nights ago. When I took the bag of kitty cat poop to the dipsty dumpster the day I installed it, it was aimed well higher than what would be preferable. So yesterday, I added a shim made out of a small cardboard box and tested it again after the sun went down - it was aimed properly this time.

UPDATE 02-08-07:
No, you're not seeing things.
Yes, a same-day update.

Here is a photograph of the light emitted by the Light Cannon when used as a headlamp as described earlier today.

UPDATE 02-09-07:
I went to the store much earlier than usual this morning - approximately 6:30am PST - and of course, I had the Light Cannon in my arsenal. Had I not had it there, I would not have driven my scooter to the store - yes - it was that dark.

UPDATE 07-14-08:
The link to the $61 bulbs on my 06-23-05 update is no longer any good - it simply points to a domain parking service now. Therefore, I have removed the link.

Extremely bright blue-white light
Relatively easy to hold with pistol grip
Casing is durable and light is submersible to 500'
Uses common and easily available "C" cells.
Can also use rechargeables if desired.

This is the heaviest light tested to date.
Lamp is more fragile than I'd like to see in a handheld flashlight.
No support for recharageable batteries - you have to disassemble the unit every time you need to charge the batteries.

      MANUFACTURER: Underwater Kinetics
      PRODUCT TYPE: Handheld diving light / video light
      LAMP TYPE: Metal Halide HID, 10W
      No. OF LAMPS: 1
      BEAM TYPE: Defaults to a fairly narrow spot; alterable with included filters.
      SWITCH TYPE: Locking rotary switch on barrel
      CASE MATERIAL: ABS plastic
      BEZEL: Rubberized & ribbed, with finely stippled (orange peel) reflector, clear plastic lens.
      BATTERY: 8 alkaline or NiMH or NiCd "C" cells
      CURRENT CONSUMPTION: Approx. 1.25 amps
      SUBMERSIBLE: Yes, to 500 feet
      ACCESSORIES: Duracell batteries, two diffusing filters, pistol grip, and padded wrist lanyard
      WARRANTY: Limited Lifetime, except batteries & bulbs
      SIZE: 8.2" long by 3.2" diameter (at bezel)
      WEIGHT: 2.5 pounds fully loaded


      Star rating

UK Light Cannon 100 *

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