Portable Light Sources
I have been running Low-Light classes now for almost 10 years, and I have been operating in low-light Professionally almost 10 years more. But honestly, I started as a kid playing capture the flag and other such activities. I learned a lot playing in the woods and cornfields at night.
There were techniques I learned, that I took for granted that everyone knew. Like closing one eye when you were going to be exposed to light. Thus, keeping your night vision in one eye. Or the longer you’d stare at something at night, the more it would appear blurry. Simple things like that, to the uninitiated, are mind blowing when experienced.
We all know that we need Tac lights on our rifles, pistol lights on our pistols, handheld lights in our pockets, headlamps in our go bags, emergency lanterns / work lights at home and in our vehicles, but where do we begin? Most likely, you already have most of these bases covered, but we’re always trying to improve ourselves and our equipment. In this article, I plan to give you information to assist you in equipping yourselves with light sources.
We’re going to start with the most common used terms and explain why they may not be the end all be all of making your decisions.
LUMEN: You need to understand that lumens are just a form of measurement that tells you how much candle power a light source has at the distance immediately after the lens of the source. As used in reference to flashlights, it refers to the total amount of light radiated by the bare lamp, the LED, or the flashlight. Because this measurement does consider the focusing efficiency of the reflector, it does not indicate how "bright" the focused beam will appear. A flood lamp with a very wide dim appearing pattern can have the same lumen rating as a very tightly focused intensely bright spot lamp assembly.
CANDELA: This is giving a power measurement for the cone of the light. It is also called candle and at one time it was equal to the light from an actual burning standard candle. One candela is equivalent to 12.57 lumens.
These two measurements don’t necessarily tell you how good a light is. One of my hobbies is photography. In that, I have a lot of experience with light. A reference that you all may have heard, another measurement relating to cameras, is the MEGAPIXEL (MP). Just like lumens, different companies will brag about how many megapixels their camera has. The higher the MPs does not mean the better the camera. It’s often used to try to sell you something. You’ll have a cheaper company that brags that their camera has 36 MPs, but that camera is trash. Nikon’s D6 only has 20 MPs, but it is still the superior camera. This has much to do with the processor, but more importantly, it’s the optical quality of the lenses. So, just the same as you can go online and find a cheap tac light that may have 600 lumens, then compare it to a quality light that only has 300 lumens, there is more to consider. The component parts of the quality light are better, giving you a brighter light at distances and a more focused beam. So, don’t be fooled by a number.
A better way of calculating a light’s power is to test it at different distances and see how it performs. Find out what the fall off is, meaning at what distance you start to lose visible light. In photography, we refer to light power, not by lumens or candela, but by F-STOPS. This comes from measuring the aperture, or opening of the camera where light enters, required to get a correct exposure. I am by no means trying to bore you with photography terms, however, it’s easier to explain by using the f-stop method. So, in calculating the power of light, being the fact that light is a wave, we must utilize the Inverse Square mathematical formula. See included example.
But, to explain it in layman’s terms or 18 Bravo language, you can calculate how weak a light source will be at a given distance by utilizing this formula. If you know that you need to see at 100 meters with your light source, and you know that for your eyeballs in a low-light situation, you need a certain number of lumens. By using the Inverse Square mathematical equation, your starting power needs to be high enough to make up for the loss of power over distance. But, keep in mind, power is not the only thing that is affecting the output of that flashlight. Just like the camera example, the lens quality and the reflective surface can have a good deal of impact on the light’s capabilities. The “so what” of all of this is? It simply comes down to educating yourselves a little bit before you make a purchase and not being fooled into buying something that won’t work for your needs, or spending more money than you need to for something that is overkill, or because it is the “latest and greatest.”
https://byjus.com/inverse-square-law-calculator/
https://www.rapidtables.com/calc/light/lumen-to-candela-calculator.html
https://www.rapidtables.com/calc/light/candela-to-lumen-calculator.html
Let’s talk about rifle lights. One of the best questions to ask is, “What is the main purpose of this light source?” A light on my rifle is for target identification. You need to decide what the farthest engagement that you expect you’re going to run into with this weapon system. If you’re expecting to engage targets at 200 meters, you need to make sure your light is powerful enough to identify a threat at that distance. I know that there is a concern of having too powerful of a light and working inside an urban area, potentially blinding yourself with your light reflecting onto you. I’m not saying this isn’t a possibility, but I am saying it’s not very likely. I’m always more concerned that I have the ability to see my far target. And like all things, training and using your equipment will definitely help you understand what that light is like coming back at you. This is why in our low-light classes, we like to have you use your flashlights in and around objects, that way you’re familiar with the way your equipment behaves. Important things to remember when mounting a light on your rifle, you must be able to access it with both hands. If you’re utilizing a tape switch, make sure that you have a back up system for when it fails. Make sure that you train with your equipment and know where your buttons are. A white light ND can be catastrophic to the mission by letting the bad guys know where you’re at.
Pistol lights. We are living in the 21st Century. All modern handguns come with a rail allowing us to mount a light. It is vital that we have the ability to illuminate our targets. For years, the gun industry has been upselling us with night sights. You still must be able to identify your target, and that is what the pistol light allows you to do. When purchasing your pistol light, focus on the construction materials that the light is made of. There’s the possibility, if you’re in a defensive situation, you may have to use the pistol as a striking weapon before you can take a shot. Also, combat is a very dynamic sport, you trip and fall a lot, I KNOW. You don’t want to break your pistol light on the ground or your attacker’s head, you might need it later. We have always recommended getting a pistol light that protrudes past the muzzle of your pistol. This aides in protecting the slide from being knocked out of battery in a fight.
Handheld and pocket lights. This is the utility light. It’s for all tasks needing illumination without waving a gun around. I.e., I drop my keys and they went under the car in the parking lot, one of my stupid chickens is missing and it’s decided to roost in a tree somehow. Think of this along the same lines as a pocketknife, it’s not there for fighting, it’s there for utility. Push comes to shove, absolutely I can fight with my utility light. Therefore, I will look at the same requirements as I do for my pistol lights. All metal body construction, powerful enough to push the light beam out that 100 - 150-meter mark, but all these things have to be balanced with the fact that this is a pocket light not an old school Mag light. We know what those 3 D cell batteries are for.
Headlamps are especially useful when needing to cast light into my immediate workspace and keep my hands free. This is an area that you should look at going with a lower powered light. You don’t need your headlamp to shine 300 meters away, it needs to illuminate your immediate workspace. I’m a big fan of headlamps that the first setting is just a red LED. Usually, that gives me enough light to accomplish whatever task I’m trying to do with the ability of turning on a brighter white light if I needed.
Last set of lights that I want to talk about are the lantern / work lights. This is going to illuminate a larger area giving the ability for more than one person to benefit from the light. In my ruck, I like to carry an inflatable LED solar-powered lantern. It gives off a good amount of light and takes up little space with no weight. In my truck, I like to have a battery-powered work light. I use a DeWalt because I have the DeWalt battery system. You may want to consider and research the upsides and downsides of the various systems before settling on one. I like that the work light I have has the option of running on an AC adapter, allowing me to use the inverter in my truck to plug the light in if I don’t want to deplete the battery.
We can’t talk about portable light sources without talking about batteries. This can be an entire article in and of itself. Here are some things to think about when it comes to batteries. Try and keep as many of your battery powered objects using the same type of battery. This cuts down on the need to carry various battery sizes. There are several flashlight manufacturers that make handheld lights that have the ability to use more than one size battery. My pocket light can use either a CR 123 or an AA. I’m a big fan of versatility. Be careful when it comes to rechargeable batteries. There are some great systems out there that are rechargeable only. On paper, this is a great idea. They are smaller, have better weather sealing making them water resistant, but if you find yourself away from your charger, it can be a bad day. If your flashlight has the ability of using both rechargeable and disposable batteries, even better. I like the options. Just make sure you have that back up. Also, remember when it comes to Lithium batteries, they can be affected by the cold, so store appropriately.
Portable light sources can make a night and day difference in a bad situation. But, like all items, it’s part of a system and if we’re not training and practicing with them, just because you have it, doesn’t mean it’ll do the job for you. You must become experienced with all your equipment in all conditions, day, night, sunshine, or rain, that way it will be an asset to you. Share what you’ve learned with a friend, it might brighten one of their future bad days.
We hope you found this article illuminating.
Jared and Chris
Some more terms you might find useful pulled from the Streamlight website:
BEAM CANDLEPOWER: Also called Peak Beam Candlepower. Measurement of the brightest spot in a focused beam. An indication of the maximum intensity of the flashlight. The "hot spot" is equal in brightness to the number of "candles" required to produce the same illumination.
BEAM PATTERN: Flashlights have a different balance of features in terms of how wide it is or how far the beam will reach. Your choice of flashlight should be determined by your intended use. Some of Streamlight’s beam patterns include:
Tradition: General, multi-purpose use, giving optimal balance of a far-reaching beam and ample peripheral light
High Performance / High Lumen (HPL): Throws light a long distance and is good for down-range applications with an enhanced lumen output
High Lumen (HL): Widest beam pattern, ideal for maximum illumination in smaller areas where a lot of light is needed, but not an exceptionally long reach
CANDLEPOWER: When referring to flashlights, candlepower is usually the same as beam candlepower.
HALOGEN AND XENON BULBS: Flashlights using bulbs filled with these gases are recognized by their extreme brilliance and white light. These bulbs are generally more efficient than ordinary bulbs and may last longer.
LED: LED (Light Emitting Diode) A high-intensity "solid-state" bulb which lasts up to 100,000 hours. Able to run for very long periods of time on very little power. Available in various colors including Ultra Violet.
Lumination – is light emission and relates to the performance of the light itself. When you turn on your visible light, that is lamination. It’s not until we cast the light onto an object, that we ILLUMINATE it. Illumination is often used interchangeably for both, as we usually turn on the light to light an area, though not the same.
Lux – refers to the intensity of a light cast on an area (1 lumen per meter squared = 1 lux).