The Danger of Light

I was wondering, at what point does light become immediately damaging to the eyes?

I was thinking of my 80 lumen P60L, and that gives some spots in day adapted eyes, and I'm guessing it gives flash blindness in dark adapted eyes.

I was wondering, if I got the 250 lumen D26 LED by LF (yes, I realize that it's not actually 250 lumens) would that pose a threat to people if it got in their eyes (fellow walkers) if I'm on a dark sidewalk?

What would happen with 1000 lumens?

And finally, how can I chart the eye's sensitivity to light? I have an idea in my head that relative brightness is logarithmic, but I don't know....

Thanks much!
Flash

Not as dangerous as you might think.

Think about it. You never hear of people becoming permanently blinded by looking into car headlights because it doesn't happen. People can blink fast enough to prevent damage. I don't remember the value, but the threshold above which you can't blink fast enough to prevent damage is VERY high in intensity.

Think "arc welding" bright.

lol

If you mean danger as in permanent eye damage, it's not going to happen with any of our flashaholic lights; you see car headlights all the time and those are ~1000 lumens, and the strobes on emergency vehicles are at least as bright.

That being said, if you're walking down the sidewalk and shine your light in someone else's eyes, the threat will be the now-annoyed person and not your light.

As far as light sensitivity goes, it all comes down to how dark it was before you turned the light on, and only then how bright the light actually is. With totally dark-adapted eyes, a 2 lumen light looks "about right", or what you'd expect from a common flashlight. Yet in daylight, you'll barely notice a 600 lumen light. Since the pupils of the eye adjust for ambient lighting conditions, it all comes down to the before and after difference.

great! so I'd basically need the brightness of an atom bomb to do much damage.

anyone know how bright a flashbang is? yes ironic with the name and all, but I'm genuinely curious

Not exactly sure about flash-bang lumens but I did have a trip flare get set off in my face one night when the last guy in my squad ignored my halt command to come up and check out what I was doing. I was cutting the trip wire on it! IDIOT I was blinded for awhile and he was court marshalled. All I can say is thank God it wasn't a live mine, we would of all died. Training can be dangerous too with guys like that along.

LED lights don't really give off much radiation beyond that of visible light (like IR or UV) like lasers or the sun does, so they probably won't cause the same problems either of those will.

You must remember the Sun is about 50,000lux.!:huh:

From what I read, blindness from light doesn't have to do with output but how much area produces the output. A laser has much less output then a flashlight but can produce blindness because it produces a good amount of light from a very small source. Same with the sun(if you look at the light to area ratio).

From what I read, the main thing you should worry about is a high lumen to area ratio, and IIRC a LED is a good amount below the danger threshold.

I don't think lumens are relevant in this case. You would want to consider the lux, as that is the measurement of what is perceived by the eye, and it also takes distance and intensity of light into account.

I wonder if looking into a Polarion PH50 could do any eye damage. At one meter is was off my lux meter, which means it was more than 200,000lux at 1 meter, and that was with the PH40!

Your eyes can probably deal with anything up to 100,000 lux without long-term damage. The light source we evolved under is that bright sometimes. Many lights, even LEDs, can exceed that by a large margin if purposely held very close to the eyes. At normal viewing distances, on the other hand, few lights are intense enough to worry about.

foxtrot29 said:

Think "arc welding" bright.

lol

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Yeah, but IIRC, the burns from arc torches are cuz of the UV - it's not "blinded" by light, but rather burned by radiation. Kinda different. you actually destroy the cells at the retina.

WadeF said:

I wonder if looking into a Polarion PH50 could do any eye damage. At one meter is was off my lux meter, which means it was more than 200,000lux at 1 meter, and that was with the PH40!

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My guess would be that it would hurt like the ****ens, cause temporary blindness, but no long term damage. It would be a REALLY nasty thing to do to someone, but not damaging. That's my fairly uneducated guess.

I always shine my lights in my own eyes, sometimes... :shakehead

I don´t know, but sometimes I do it to see if they´re strong enough, and I always got blind for 1 minute, or became with blackdots in my vision...

Am I the only one that do this ?

Federal LG said:

I always shine my lights in my own eyes, sometimes... :shakehead

I don´t know, but sometimes I do it to see if they´re strong enough, and I always got blind for 1 minute, or became with blackdots in my vision...

Am I the only one that do this ?

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I've done that too... not always but definitely more than once... maybe sometimes... or a bit more often than sometimes... but definitely not always...

Sgt. LED said:

Not exactly sure about flash-bang lumens but I did have a trip flare get set off in my face one night when the last guy in my squad ignored my halt command to come up and check out what I was doing. I was cutting the trip wire on it! IDIOT I was blinded for awhile and he was court marshalled. All I can say is thank God it wasn't a live mine, we would of all died. Training can be dangerous too with guys like that along.

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Scary situation, Sarge. You're right, lucky it wasn't live.

Looking into any arc light, even HID's without a UV filter can produce damage over a long time. I have personally looked into lights up to 3400 lumens and although that one blinded me for a few minutes, I'm perfectly fine. As mentioned before, the number of lumens for once doesn't matter... at least not when compared to how colaminated the beam is. This is why a 100 mw laser is so dangerous while a 35 or even 50 watt HID is alright (aside from the UV danger).

Federal LG said:

I always shine my lights in my own eyes, sometimes... :shakehead

I don´t know, but sometimes I do it to see if they´re strong enough, and I always got blind for 1 minute, or became with blackdots in my vision...

Am I the only one that do this ?

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Yeah, I know what you mean. I also really hate it when people shine their flashlights into your eyes on purpose, even if it doesn't leave permanent damage its still really, ridiculously annoying.