In this article we discuss how light works with our eyes, and how tactics and technique can help us minimize risk in the low light environment as citizens.
Imagine living 300 years ago; darkness was an uncontrollable part of your existence. Barring a lantern, a candle, or the light of the moon, once the sun set, so did your ability to see.
Flash forward to the present day world; light is a permanent part of most environments around the world. It can be made at the flick of a switch or press of a button. Ambient lighting lines our city streets, shops, and homes. A world that was once off limits to us has changed so drastically we’ve coined a term for it: Light pollution… and it’s utterly changed not only the lives of humans, but of animals and ecosystems.
We care about this because we’re used to being able to see.
So what happens when we can’t?
Vision and Fighting
Our primary sense as a human being is vision.
Exploiting our adversary’s lack of ability to take in and process visual information is one of our major advantages in warfare. Night vision devices, thermal imaging, and the tactical use and depravation of light are all components of modern warfare that stack the deck in our favor. However, for the citizen who may find themselves confronted with low-light emergencies in a more ambiguous sphere of violence, these advances mean almost nothing.
Whereas military forces often have intelligence as to the type of threat they’re facing, technological superiority, and a network of support from close air support to casualty evacuation, the citizen has skill and wit. Why then has the use of light doctrine from the military sphere of violence been carried over to civilian training?
Well, let’s start with how they’re similar:
- -Use of angles are universally important
- -Movement (while different) is a critical component of both
- -Equipment can be common (handheld lights, weapons mounted lights, etc)
Next, let’s talk about something else we have in common: anatomy and physiology.
A&P: How the eyes work
Understanding what’s going on in the eye as light conditions change helps us make good decisions about how we use light. This is going to be a high level discussion, because as with all our articles, we want to present you with a resource that can continue to help you learn no matter what your skill level.
So, what is the eye and how does it work?
The human eye is an organ that turns light (photons) into chemical signals. For our purposes, we’re interested in three main components:
- Visual Fields (how we see what we see)
- The effect of light on vision, and;
- The influence of distance on our vision
Our visual field is broken into two types:
- Foveal (forward looking) vision allows us greater detail and focus.
- Peripheral (oblique vision) vision allows us to sense movement from oblique angles.
This makes the human eye very good at both detecting threats approaching from the sides and quickly adjusting our vision to give threats greater scrutiny.
How natural night vision works
The iris (colored portion of the eye) is a muscle that can expand and contract the pupil allowing light into the retina to be converted to visual information. The biochemistry behind this is a little more complicated than this, but here’s the basics:
The retina itself is lined with nerve cells called cones and rods. Cones relay information about the wavelength of light, giving our vision color, while rods allow gray-scale vision during twilight and low light.
Within the rods of the eye, a photosensitive protein called Rhodopsin allows us to absorb photons and recombine Opsin and Retinol so that we see with less clarity and focus, but perceive more light.
Once rhodopsin comes in contact with photons, it splits into opsin and trans–retinol, giving us the ability to see detail and color.
So our eyes essentially have a budget of proteins that slowly adjust to meet the light cycles humans have historically experienced.
Distance and Clarity
The final consideration we need to take into account is how the distance of an object impacts visual clarity; the reason is the farther an object is from our eye, the less space it occupies, and therefore, the less information is available to our brain. That means in low light, more distant objects are even less discernible than they’d otherwise be…This little lesson is important because as we transition into how to fight in low light environments, we want to know what’s happening… both with our own ability to process information and our enemy’s.
What we need to take from this is that there are several factors that are crucial to our ability to make good decision under stress:
- – Our ability to see (right amount of light)
- – Our focus (detect threats)
- – Our ability to deny vision and focus to potential adversaries
- – The role of distance and lighting on perception in high stress situations
Because of this, it takes about 30 minutes for opsin and retinol to reconfigure into rhodopsin, but we regain our foveal vision, color, and depth perception almost immediately when exposed to light.
Low Light/No Light Environment: Stats and Mistakes
The first thing we need to discuss is this: Most training these days comes from police or military sources.
Low light situations are far from cut and dry for military and police, as well.
An article in PoliceOne stated:
“Aveni points out that 51 percent of the time furtive movement was involved in the MOF [multiple officer] shootings. As many as 75 percent of the MOF shootings he examined occurred at a time of day that “we’d generally associate with reduced light conditions.” (Yet in only one report was there any indication that officers used flashlights to better identify possible threats!)
“I’ve joked for a long time that given low light and the right contextual cues, I could get Mother Teresa to shoot the Pope,” Aveni says. “Cops never think they’d shoot an unarmed person inappropriately. But on the street when they have to make split-second decisions, it can happen easier than they think.”
With that in mind, it’s perfectly acceptable to verbally confront people you encounter or to take a defensive posture rather than trying to track them down. The confusion that occurs in low-light environments is often deadly. This solution is not only more prudent (especially for citizens), but it affords you a lower threat signature, and the element of surprise if you *do* need to defend yourself.
In addition to verbal challenges: How often do you train to hold your fire at the end of a draw stroke?
Said another way: do you draw your pistol and make a decision to shoot, or do you just train to shoot?
The reason for this question is that every year, dozens of innocent people are shot under conditions Claude Werner has dubbed ‘negative outcomes’. A significant number of those go something like this:
‘Man shoots son returning home late from party.”
The cause for this is a convergence between three major issues:
- Lack of adequate identification
- Training to shoot without making decisions before pulling the trigger, and;
- The belief that you should be able to shoot anyone who comes in your house.
Our primary goal is always to “lose the least”; as citizens, we’ll never win if a gun goes off. So please, incorporate thinking into your training.
Low Light Emergencies
Because the citizen could find themselves in anything from an Active Shooter crisis against multiple assailants with rifles, or a simple break in at their home, as much of the thinking should happen before the fight as possible. This means training.
Low light doctrine is mostly about how to move and use light in an intelligent way. Done correctly, light does a few things:
- – Overwhelms the adversary’s ability to see past the light, creating a ‘wall’ (Remember vision comes back faster in light)
- – Gives us visual information
- – Betrays our location to anyone looking
- – Resets the eye’s ‘night vision’
For those reasons, using a momentary on to take information while moving allows us to see more clearly for identification and hazards, while not remaining in one spot long enough to take fire.
This is all well and good and should be trained on, however, in the civil world, often times light is not so cut and dry. Before a raid, SWAT or SOF can disable a buildings electrical infrastructure, leaving the occupants without control over the light within. We don’t have that luxury.
How do we deal with this, then?
We need to use light to gather some primary information from which we can make decisions:
- What parts of the room introduce transitional spaces? (Doorways, blind corners, etc)
- What obstacles are in the room?
- How can you use the layout to your advantage? (Cover, concealment, etc)
- Can you simply turn the lights on?
The idea shouldn’t be to ‘clear’ a building the way a police officer or tactical team member would; we want to establish points that are difficult to pass through without being detected, and from which our enemy will have a hard time passing without putting themselves at a disadvantage.
Transitional Light Environments
Transitions in light are the very basis of the gradient, but they’re also a distinct hazard that must be considered; whether you’re moving from a lit room to an unlit room or from a daylight environment into a darkened room, you are moving across a gradient that puts you at a disadvantage. Conversely, if an unknown contact or hostile party is forced to cross these light thresholds, it is likely that you will be able to see them before they see you. Good tactics, in this case, mean minimizing your exposure time in these transitional areas, and putting unknown contacts in a position where they have to cross them to get to you.
This happens because of backlighting. Backlighting creates a silhouette, which is easy to identify if you’re looking out from the dark and into the light environment. This often creates the additional disadvantage for the party moving from the lit environment, as their eyes are subject to the recombination of retinol and opsin once again as they move into the dim/unlit environment.
For this reason, understanding the environmental light gradient and how backlighting creates a silhouette is a critical point for our further understanding of how to use light to our advantage.
So, where do we start if we are faced with this situation?
Recall from my earlier Understanding Emergencies article the concept of “OODA” by Col. Boyd: Observe, Orient, Decide, and Act. Once you enter the threshold, you are committed to your course of action. So, when making a decision on transitioning environments:
- Observe the entryway from a sharp, oblique angle that disallows those on the inside to look out. Careful to avoid standing in front of windows – this is a sure way to silhouette yourself, as you’re backlit.
- Orient yourself to the threshold itself. Is it a door? A hallway? Is there a handle or knob? If so, which way does it turn? Which way does the door open? Are you in a linear corridor? An open area? If you cannot get in through the proposed threshold, where is your next entry or egress point? These are all questions that can rob you of precious seconds in a tense situation, so learn to spot and analyze these features as you orient yourself.
- Decide if passing through the threshold is in your best interest. Are you putting yourself at an unnecessary risk by doing so? Is there an urgent reason to enter? Are there alternative ways to enter? How about to exit? Is it likely that there will be people inside? If so, what is their disposition (hostile, neutral, friendly) and how will your entry impact them?
- Act out your course of action. When you do, be committed, firm, and resolute that your decision is correct. If it is not, get yourself out of the situation before considering all the ways you could have done better or different.
This component on environment cannot be overstated. Making good, efficient, and rapid decisions is going to be a time-saver in a tense situation, and time saved could very well be lives saved. The more you know about the area you intend to enter, the better. It could be the difference between entering, turning on the light switch and finding what you’re after, or moving quickly across a threshold and continuing a very deliberate low-light search for safety.
Finally, consider that in many disasters in which power is out, we still have transitional light environments; it may be bright daylight outside, but as soon as you go indoors, the clock on your natural night vision resets if you don’t have a torch handy. That can make navigating the post disaster environment a challenge, if you’re not properly equipped.
Equipment and Usage
On this topic, plenty has been written. You can find opinions from professionals in any venue giving information to validate whatever decision you make, so let’s discuss some of the lesser known characteristics of light use, as well as provide a basic primer on terms.
Bottom line up front: We prefer medium output (350 lumens or so) lights with more splash than throw for utility lights. The simpler the light is, the better. You don’t need 8 modes. You don’t need different buttons. Under stress, you want simple, durable, and sufficient.
Lumens are a measure of how bright a torch is. It can apply to any light, from a lantern to a weapon light, and has the internet firmly divided into two camps; those who believe you need as many lumens as possible, and those who feel too much illumination is a disadvantage based on how it affects their own vision. Not all lumens are the same. There is emitted light, and forward light. Lights with higher emitted light (even at the same lumens) will behave differently than those with more forward light, or throw.
- Throw (forward output)
Our forward light is referred to as “throw” This means that the illumination tightly bound within small, bright circle. Throw typically translates to better long range illumination, but at the cost of illuminating the general area. Indoors, a torch with high lumens and a focused throw can wash out the target, and even make it difficult for you to see. Some people believe that this is a ‘weapon’ of sorts and serves to blind your opponent. Our experience is that it’s less important than people make it out to be, but test it for yourself.
- Splash (or spill)
Splash is the opposite of throw: it’s a broad circumference of light in which the illumination is more spread out. This leads to a less powerfully focused beam, but it tends to reveal more information in general. Because it’s less focused, there’s less risk of a light with higher splash and less throw washing out important information about the target.
Types of lights
One of the first questions is “what type of light?”
A lot of this depends on your intended use; is this a tactical light for a weapon? Is it general purpose? We’ll look at pros and cons of each.
- Hand Held: The hand held is the ubiquitous flashlight. It could be anything from the huge Maglight to a tiny, single CR123 powered LED light. Typically, the handheld flashlight is the most useful and least obtrusive tool. It’s a common use item that is useful in many day to day tasks. It’s primary drawback is that it requires a hand to use. If you have to employ a handgun, this means your accuracy will likely degrade.
Pros: Can be used independently from firearm. Allows you to illuminate a target without pointing a weapon at it.
Cons: Degrades accuracy, occupies support-side hand (Which can make other transitional tasks like opening doors or using a phone difficult)
- Weapon Mounted: The weapon mounted light is far superior to the handheld in terms of maintaining accuracy under pressure. The problem is, if it’s your only light, you’ll find it looks pretty amateur to pull your pistol to light something up. Additionally, there’s mounting evidence that the sympathetic reflexes of the hands can bring about negligent discharges when trying to use WML’s under pressure. If you choose a WML, additional training under pressure should be a non-negotiable component.
Pros: Allows for greater accuracy while illuminating threats.
Cons: More difficult to operate under stress. Requires pointing a weapon at potentially non-hostile unknown contacts. May cause reliability issues.
- Strobe: Strobing lights do two primary things for you as the wielder; they make your movement very hard to track, and they disorient anyone looking for you. The feature can certainly be helpful if it’s very dark, but often as not, you won’t be the only one with a light. This can affect the usefulness of strobing lights.
Pros: Disorients adversaries, makes user hard to track in very dark environments.
Cons: Often requires complicated switches or mode selections. (Stick with single button! Complicated lights are a recipe for disaster – you want to know exactly how your light will behave when you turn it on.)
This hold became popular due to the notion that bullets follow lights, which is an assessment made for good guys, by good guys. Not to say it isn’t true, but with good light discipline, this hold becomes (in my opinion) obsolete, and while it still has a foothold, it’s not very useful if you’re not using it in conjunction with a firearm.
Pro: Keeps light away from body, and theoretically confuses aggressive action.
Con: In practical usage, it’s difficult to use this technique when going through doorways or in confined spaces. It tends to snag or hang up if there is a 540 degree debris field (as occurs in emergencies), and perhaps worst of all, it is harmful to your balance and compromises your postural dominance if attacked.
Pro: The Rogers is a good technique that allows for a solid, effective grip on the light. Activation is done with large motor skills (palm press rather than finger press) which I find to be easier under stress. In addition, I find it to be a bit more stable while using a firearm, and it points very naturally.
Con: Requires a specific type of light to use – if it doesn’t have a Surefire-type tailcap activation, the Rogers technique is going to be a bit clumsy. It also is a bit unnatural if you’re not using it with a weapon, as other grips allow better control over the light.
PRO: The Harries hold keeps the light in an aggressive forward grip, at centerline, and makes it easy to transition between this position and the neck index. It also allows quick, effective strikes if one sets up their light as an impact tool. HOWEVER – do not attempt to strike if you are using a firearm. This cannot be overstated. Don’t put your hands in front of the muzzle for any reason. Shooting yourself would be a ‘con’.
CON: Use in conjunction with a firearm offers little to no additional stability and creates poor balance by extending the support side arm. Additionally, it requires wrist articulation for many, which is a weak point if you are attacked physically.
PRO: Keeps hands well clear of your front, close to the body, and allows for an aggressive forward posture. Gives the same aggressive stance as the harries, but keeps the support side hand close in and secure close to the body. An unspoken benefit is that the hand and light actually block the highly vulnerable left carotid artery.
CON: This technique tends to silhouette your firearm and create ‘shadows” in your visual field. Light near the body could be a hazard. It’s also has the same disadvantage the FBI technique attempts to circumvent – the light might draw assaults.
This stance is my preference for use of light with or without a handgun. It’s a cross between the FBI, Harries, and Neck postures. Often used by bouncers at nightclubs to ID people, it keeps the support-side hand high and on cue for a defensive posture (default position).
PRO: Keeps the aggressive posture of the Harries grip on the light, and maintains the “upright” posture of the Neck Index, but cants the light out away from the body 8-12”. I like this because it allows me to keep a defensive arm up in situations that don’t require the use of arms, but may require use of force. It is also consistent, and the light is “activated” at eye level, meaning that your chances of using it as a method of distraction might help you save a second or so if things do go bad. The offset light may be enough to draw bullets away.
CON: If held too aggressively, it can obstruct your peripheral vision, and if someone approaches from the support-side rear, the arm is not as secure as it would be in a Harries or in a Neck Index. As with the Neck Index, it casts a shadow.
The tactical use of light depends on circumstance, which goes beyond the scope of this article. What we can say is that there are a few useful concepts to understand:
- Light and move: Similar to shooting you don’t want to get pinned down after advertising your whereabouts. Lights, like gunfire, let people know where you’re at. After you use your light (assuming it’s still dark), move! (links to response to active shooter medical/low-light video)
- Use short, brief sweeps of about a half second to scan. Hit the light and sweep it across the room. Look for possible areas you could be approached from, debris or obstacles that you need to be cautious of and then move.
- If your light is on: be moving. Strobe is helpful, both for disorienting your adversary and moving without giving away your exact location. Tracking someone who is moving by strobe can be difficult and it’s a feature worth looking in to.
- If you do end up engaging, remember that there are always potentially more aggressors, and you’ll need to train to keep moving, keep using your light intelligently, *and* keep track of anyone who may have been wounded. This is an advanced topic, and scenario based training should be done.
Don’t expect low light problems in the civilian world to look much like an entry team raiding a compound, or executing a high risk warrant raid. It’ll likely be a slow, sketchy process of trying to make sure as much of what’s behind you as possible is verified ‘safe’. Especially with in the home problems in low light conditions, don’t be afraid to hold ground and use your knowledge of your home to your advantage.
Remember you can always move to avoid contact and issue verbal challenges, whether in your home or caught in a post-disaster situation with unknown contacts.
If you find yourself dealing with an active shooter, be ready to identify and use terrain and structures to your advantage; limit their vision, maximize your own, dominate the angles, and fight with all you’ve got.
We hope this primer on low light environments has been helpful!