For self-defense: Graph to detail relation between lux, and severity of visual hazard

[Twinbee]

I'd like to buy a cheap torch at least partially for self-defense. Even if I get attacked at night and robbed though, I DON'T want to damage anyone's eyes permanently. Only temporarily (5-30 minute range <EDIT: even 5-30 second range would be useful>) so I can make a hypothetical getaway.

To that end, I want to buy a particular torch which is capable of around 300 lumen (claimed 500). Because it is a 'zoomie' though, it is capable of generating a great of lux when focused to get its furthest throw. I was considering this torch: http://www.amazon.co.uk/gp/product/B00NPXCB7E/

I have a decent device to measure lux. Is there a graph to detail the relation between eye hazard (glare -> flashblindness -> eye injury) and amount of lux? I understand that the eye is much more sensitive to light at night, so presumably there is greater chance for permanent injury at this time? So ideally, the graph would be split into two components (one for night-time vision (when the eye lets the maximum amount of light in), and the other for bright daylight (when the eye lets the minimum amount of light in).

Failing such a graph, can anyone here give me a quick indication (in terms of lux) of what amount will merely cause glare, or more ideally causing temporary flash-blindness, versus causing permanent eye injury? Numbers would be good.

 

[FRITZHID]

1klm is a good start.
I've found in my exp that 1klm and up, tightly focused, is a fairly good "temporarily blinding" brightness. ... Espc for night adapted eyes. I've found that anything lower is fairly easy to recover from.
Keep in mind that blink response plays a big factor as well. A pulsing/strobing light has a better effect than steady beam as well, very disorienting.
I've tested 4 of my brightest lights and yes, the lower 500lm lights will work to some extent but my 1.4klm Coast and my maxabeam (1.1klm) are far more effective when focused properly.
I've also found that an uber tight focus is easier to avoid than a slightly flooded spot.
At target distance, a spot slightly bigger than the head of your target is ideal.
Worrying about actual eye damage is really not that big of a deal, it takes allot more power/cm² then LED flashlights will provide before blink/pupil response will kicks in, but flash blindness is temporary and would give the seconds needed to attack/avoid/run.
There's a whole thread on the effects of "strobe mode saving lives" somewhere here on cpf that may have clearer answers for you.

 

[bykfixer]

That's one bad@$$ little light there.

Features found in a much more expensive light.

Now the other day I got spotlighted in daylight by a 65 lumen xenon bulb. Saw blue stars for about the next 24 hours.

 

[FRITZHID]

Now the other day I got spotlighted in daylight by a 65 lumen xenon bulb. Saw blue stars for about the next 24 hours.

If you saw stars for a day after a 65lm flash, your eyes have problems. My cell phn light is more than 65 lm.
You say xenon, is that a hotwire xenon, HID xenon(even exists?), or a short arc xenon(pretty sure doesn't exist)?
A hotwire xenon won't cause stars for an hr let alone a day. Even my maxabeam 75 watt short arc xenon won't cause stars for a day..... Unless you're foolish and stare at the bare bulbs arc for a few seconds at close range and even Then it's uv arc burn, not the "eye bleaching" that a bright light will cause to night adapted eyes.

 

[bykfixer]

It was a 6p incan. Heck if I know hot-wire/non hot wire... I didn't think to ask the cop so that pixel counters at cpf could discern whether his light meets the test.

I do know I was see-ing stars the rest of that day.

Sounds like cops could save a lot of dough on flashlights and down load your celphone lamp app.

 

[Grizzman]

I'm not aware of any graphs, or even official studies, documenting required lux to cause eye bleaching.

Anyone (that has "normal" vision) that receives a blast from your cheap light won't receive any permanent damage. Fritz's suggestion of 1000 tightly focused lumens should be adequate, though if the target isn't stationary, a somewhat larger hot spot can be beneficial.

Something to consider is that if someone has serious plans to harm you, no light, no matter how powerful it is, will stop them. What you can hope for is that simply being illuminated will be enough of a deterrent that they'll go after an easier target.

I've never heard of the OxyLED brand of lights, so can't comment on the suitability of it for your intended purpose, but I will say that even a 200000lux light won't give any benefit if it doesn't work, so it would be wise to assign reliability equal importance as brightness.

 

[Woods Walker]

I'd like to buy a cheap torch at least partially for self-defense. Even if I get attacked at night and robbed though, I DON'T want to damage anyone's eyes permanently. Only temporarily (5-30 minute range) so I can make a hypothetical getaway.

Personally I wouldn't worry about the health of those who attack you. I do feel a flashlight is a very questionable self defense tool but that's just me. I did shine 500 lumens by mistake in my eyes yesterday and can see just fine if that's worth anything.

 

[GearHunter]

It was a 6p incan. Heck if I know hot-wire/non hot wire... I didn't think to ask the cop so that pixel counters at cpf could discern whether his light meets the test.

I do know I was see-ing stars the rest of that day.

Sounds like cops could save a lot of dough on flashlights and down load your celphone lamp app.

yet you took the time to ask him model, lamp type and output?

to the OP. Why on earth would you worry about the eye health of some scumbag that was about to attack/rob you? My advice ( which I follow by the way) is get a light with enough output to light up the target so your shots count and let the piece of crap hold two in the black.

 

[WalkIntoTheLight]

You're not going to cause any permanent eye damage with a flashlight, no matter how bright or tightly focused. At "attacker" distances, a flashlight will have far less lux on the attacker than daylight sunlight. Sure, at night, a bright light will seem a lot brighter for a few seconds, but unless you also use toothpicks to hold his eyes open while you shine your light in his eyes, he'll simply blink it off.

The only way you're going to even temporarily blind him for the 5-30 minutes you want, is to use something like a green laser in the 100+ milliwatt range. But you'll have to be accurate! And, yeah, he might also get permanent damage from that.

 

[Twinbee]

Thanks all - the general consensus here is that there is almost no risk of causing anything beyond temporary blindness, so that puts my mind at rest. Just a few things though...

Personally I wouldn't worry about the health of those who attack you. I do feel a flashlight is a very questionable self defense tool but that's just me. I did shine 500 lumens by mistake in my eyes yesterday and can see just fine if that's worth anything.

How focused was the torch when you did that, and how close to the torch were you? How long were you flash-blinded for, and what was the ambient brightness like (day or night?).

Something to consider is that if someone has serious plans to harm you, no light, no matter how powerful it is, will stop them.

It may give you those vital few seconds extra to escape though, especially if they're blinded for a few seconds as they won't be able to pursue you, and even if they do, you can give 'em more of the same.

I know I said 5-30 mins at the start of the threads, but tbh that's a bit overkill for my needs, so I take that back. Even 5-30 seconds would be great.

Sure, at night, a bright light will seem a lot brighter for a few seconds

Not just 'seem'. More light is literally entering their eyes and so damage is more likely (even if still improbable).

Why on earth would you worry about the eye health of some scumbag that was about to attack/rob you?

As scummy as that person might be, lifelong blindness is not to be sniffed at. I'd rather be dead than blind, and so it's a rather disproportionate response if they're 'only' going to rob you.

 

[GearHunter]

rather disproportionate response if they're 'only' going to rob you.

Nevermind, I just noticed you are from the UK.

 

[bykfixer]

yet you took the time to ask him model, lamp type and output?

to the OP. Why on earth would you worry about the eye health of some scumbag that was about to attack/rob you? My advice ( which I follow by the way) is get a light with enough output to light up the target so your shots count and let the piece of crap hold two in the black.

Uh, no...I know/knew what a 6p is. I asked a police officer what type of light he uses and he showed me.

Simply trying to point out to the op that one does not have to have a 1000 lumen out the front to make a would be robber blinded/irratated long enough to provide some time to escape or other self defense option.
And also to point out that it does not even have to be an LED light.
Millions of parked teenagers were blinded by policemen's flashlights at many a make out spot long before LED high output flashlights were invented. And all lived normal lives without retina damage or pre-mature cadaracts.

Now maybe in Amsterdam some junkies are being subjected to eye destroy testing in exchange for free heroin by kooky scientists being paid for by trial attornies...but charts are in Danish so we not understand it anyway.

But when you're under attack, the geneva convention goes out the door. Unless you are worried about the attacker filing a law suit don't sweat it.

 

[2xTrinity]

You're not going to cause any permanent eye damage with a flashlight, no matter how bright or tightly focused. At "attacker" distances, a flashlight will have far less lux on the attacker than daylight sunlight. Sure, at night, a bright light will seem a lot brighter for a few seconds, but unless you also use toothpicks to hold his eyes open while you shine your light in his eyes, he'll simply blink it off.

The only way you're going to even temporarily blind him for the 5-30 minutes you want, is to use something like a green laser in the 100+ milliwatt range. But you'll have to be accurate! And, yeah, he might also get permanent damage from that.

Green lasers that are much more powerful than 100mW, that use expanded beams, are used as non-lethal weapons in military and police applications:

https://en.wikipedia.org/wiki/Dazzler_(weapon)

The way these work is basically it photobleaches a large fractino of the eye all at once. That much visual stimulation can actaully literally stun the target by oversaturating their optic nerve with signals that their brain does not know how to deal with (this is extremely hand-wavy explanation). It's not high enough intensity to cause permanent retinal burns though.

I don't know if these are for sale to civilians anywhere, though.

No LED source that I know of, save for something like UV LED's, would be capable of causing permanent eye damage via momentary exposure. LEDs just do not have the surface brightness necessary to create enough irradiance on the retina to cause cause damage. A typical flashlight will likely not be particularly effective as a dazzler though, either.

Personally I wouldn't worry about the health of those who attack you. I do feel a flashlight is a very questionable self defense tool but that's just me. I did shine 500 lumens by mistake in my eyes yesterday and can see just fine if that's worth anything.

My guess is the reason for concern would not be empathy for a would-be robber as much protecting yourself from potential lawsuits.

 

[Woods Walker]

As scummy as that person might be, lifelong blindness is not to be sniffed at. I'd rather be dead than blind, and so it's a rather disproportionate response if they're 'only' going to rob you.

I think that's wildly delusional. No offense but it's a flashlight. Also how do you know an attacker is "only" going to rob you. Are you going to ask the criminal during the assault?

My guess is the reason for concern would not be empathy for a would-be robber as much protecting yourself from potential lawsuits.

No would be killer/robber or whatever is going to file a lawsuit because you shined a light on them during the attack. Why? It's a flashlight not a death ray. I am fairly certain it wouldn't deter a dog or other critter as well.

 

[Twinbee]

I think that's wildly delusional

You're right because I've since found out that 99% of flashlights don't reach "permanent blindness" levels of brightness anyway, especially under £20.

Also how do you know an attacker is "only" going to rob you.

It's a tricky one. I won't necessarily be pointing any fingers at those who do feel the way you do. I do think though that a VERY bright torch (say 1000-10000lm with a focusing feature) would be more than sufficient to temporarily disable someone, without seeking permanent damage to anyone's eyes.

 

[Woods Walker]

You're right because I've since found out that 99% of flashlights don't reach "permanent blindness" levels of brightness anyway, especially under £20.

It's a tricky one. I won't necessarily be pointing any fingers at those who do feel the way you do. I do think though that a VERY bright torch (say 1000-10000lm with a focusing feature) would be more than sufficient to temporarily disable someone, without seeking permanent damage to anyone's eyes.

As stated I shined a 500 lumen flashlight in my eyes just last week (actually multiple times learning the SC5w's UI LOL! ) and it really mean little. Somehow did it on strobe as well. There is a reason why I don't handle a flashlight with the same care I do for my Glock 19. Because one is a weapon and the other a flashlight. No I am not telling people to shine bright lights in their eyes. I have shined 900 lumen headlamps and 1000 lumen flashlights at deer, coons, coyotes etc etc and they didn't care. It's all good brother because debate is fun however my experience says it won't disable anyone with two or four legs. Not sure about three. This isn't to say a blinding light might not do something. Screaming for help might do something. Personally I would use a gun, knife, pepper spray or just beat the hypothetical internet debate created attacker over the head with that "10000lm" monster light. Then again how are you going to EDC such a light? I guess these days your first option of a 1000 lumen EDC is very plausible. That alone amazes me. It should amaze everyone else IMHO but how quickly do we get jaded by advances in tech. I remember when 50 lumens was a pocket rocket and now I am blowing my head off with an accidental discharge from a 1XAA 500 lumen light. Amazing. Just amazing. It's a good time to be a flashlight user!

One thing though. Reason for usage aside lumens aren't everything. A good user interface matters so maybe put that factor into the equation as well. Too many buttons etc etc etc etc could make useage under stress no matter the cause of the stress more difficult.

 

[WalkIntoTheLight]

You're right because I've since found out that 99% of flashlights don't reach "permanent blindness" levels of brightness anyway, especially under £20.

You're 1% off.

 

[Twinbee]

I know it's a little off-topic, but are there flashlights over 2000 lumen you can get in about this form factor (1inch diameter, 3.5 inch length) which allow focusing? What's the max?

It should amaze everyone else IMHO but how quickly do we get jaded by advances in tech.

Oh yes indeed. I love how quickly the tech advances. I can't wait for solid state lithium ion batteries, and even more efficient and heat-resistant LEDs!

 

[Grizzman]

In that size, 3000 lumens is available from Oveready in the form of a triple XP-L behind optics.