Ultraviolet - Sun vs Flashlight compared

Very interesting test. Actually, I’m somewhat surprised the flashlight is as strong in UV as sunlight. But, I suppose the 5x7135 configuration does produce a fairly strong beam. I still find it hard to believe that reflected UV flashlight light is much of a concern, unless you’re using it a lot.

Even more surprising is this comment:

I’m not sure what to make of that. I’ve never heard of such a thing. Closest is the sandpaper-effect that people get on their corneas from being exposed to UV-C. But that’s a real physical effect. UV should be basically invisible. Maybe some skin-burning after prolonged exposure on the retina, but that would be an after-effect.

Yes the result from my test is that the intensity is comparable, BUT only in terms of wavelength that is allowed to pass through zwb2 filter.

I think the Sun has much more damaging UV than flashlights because it is not filtered with any filter

Naw, I “feel” the same thing.

Always thought it was just my imagination, in that playing with my UV lights (shining on walls, floors, etc., to discover any… “leavings”), that I’d get a headachey feeling, or actually an eyeachey feeling, within just a few minutes.

Kinda like “sunlight headache” when you’re outdoors in bright sunlight, surrounded by light-colored sidewalks, walls, etc., and the brightness of the light all around you is just too overwhelming.

After I saw similar comments from people here, I decided it in fact wasn’t my imagination.

Are you sure it’s not from the visible violet light that is also emitted from the UV source?

Or, is it possible it’s an imaginary effect? Like people that claim they are sensitive to EMR from cell phones or wifi, but when they are actually given a blinded test, there’s no effect.

I dunno, maybe it is a real thing. I’m just surprised that something invisible could cause an immediate effect of pain. I get that extended exposure might cause pain, perhaps from a “sunburned” retina.

ZWB2 filter, too.

Wasn’t expecting any effect at all, as I’ve still got a few “black lights” (eggplant-purple fluorescent tubes) that never gave me any issues.

Playing with a bare UVLED in a ’501 host, I noticed the “headache” after a few min. Chalked it up to anything but the light. Every time I’d do it, though, same dealy.

S2+ with ZWB2 filter, same dealy. Okay, not a coincidence anymore… Ain’t violet light nor “leakage”, but whatever’s coming from the both the bare UVLED and now with the filter. That pretty much leaves UV.

That’s just it, I don’t want to get blinded, so I keep UVing to a minimum.

Wellp, I’m a bit of a hyperæsthete. Bright lights can give me migraines, loud sounds bother me (even soft sounds when it’s otherwise quiet). I gotta wear a baseball cap at work because the damned overhead fluorescents flicking at me in my peripheral vision will give me headaches/eyeaches by lunchtime.

I joked that I was part Reman, but nobody got it.

Anyway, it doesn’t surprise me that I’d be sensitive to UV.

Yeah, polycarbonate should filter something like 99%+ of UV. I was considering building a S2+ UV triple until I remembered. I know someone did it with a C8F once, would work much better lol. My other concern was that the Vf of the UV emitters tends to be pretty damn high, and I'd want some sort of compatible buck driver to do it.

Dont think so. Various gas layers around earth are more or less consistant.
UV level depends from the angle of sunlight. So all factors like season, distance to the equator and time do matter, but sometimes they may give same angle in different regions.

With the exception of politicians, most humas only have two eyes. So take good care of them.
I try to do so as good as I can. Nevertheless, there is always that itchy feeling after using a UV flashlight.
Your eyes can’t help it, they just don’t respond (contraction of pupils) very well to UV light.

For those who care, and not just down under, here is something you might wanna read.
Dr. Ruth Westheimer used to say: “Always Wear Protection”. And Jane would add: “Because You’re Worth It.”

Thanks, I was wondering about this too.

  1. Isn’t your meter meant for measuring visible light? Among other things, I think the white dome diffuser on your meter is filtering out UV light.
  2. In natural eyes, very little UV reaches the retina. Our corneas and lenses filter out UV light. That’s why things look funny after cataract surgery.

Well, I remember a friend traveling to Australia in Summer. He said without head or long sleeves he got a sunburn within MINUTES.
He is a normal middle European guy with dark hair.
So I do think be very careful with the sun down under.

I also get headache within a minute when I use my UV S2+ light without glasses.

Australian or German summer ? :smiley:

Ha! See? So I’m not the only one…

I’d still like to see a proper (double-blind) test. :slight_smile:

Oh, great, so you want him and me to go blind…

No, a proper test result is the one where 50% of the test persons are hurt beyond repair. Or killed.
So you might get lucky.

I have been working with several sources of uv light since I was 21 and the instant painful effect on my retina is real and only with uv light (i.e. not in bright sun). I can not imagine not noticing the light of a uv flashlight entering my eyes.

I’m not sure I understand the test. Can this luxmeter measure UV? UV is not measured in lux terms but in radiant output (~1800mw for the LG LED ). A special meter is required to measure UV from an LED or from sunlight. Measuring the luminescence of a material can be done by a luxmeter I guess, but is highly dependant on the material being used and the type of UV in the light source. The Convoy outputs UVA from 320nm to 400nm, with a very minor amount to visible light (compared to the amount of UVA). The sun produces UV starting at the MW range (~300nm) up to 400nm, and of course lots of visible light. Anything below ~300nm is blocked by the atmosphere (ozone layer). The MW UV from sunlight is mostly responsible for sunburns. ZWB2 is a UV pass filter with a pretty wide range - lots of MW will get through from the sun (but very little visible).

That “scratchy” feeling you get from UV is caused by wavelengths below 320nm - called “welder’s burn” - keratosis. Basically a sunburn of your cornea. Really bad, wear UV protective goggles. UVA not so bad but still a good idea to wear protection. Some people are more sensitive (can see deeper into the UV spectrum). Most can only see down to 380nm. Older folks with yellowed lenses (before cataract surgery) won’t see very much below 410nm (one reason old ladies have dyed their hair excessively blue). New lenses make a dramatic difference in the blues one sees. Artificial lenses can be selected to filter UV. Some lenses are fluorescent and can be quite problematic for people using UV lights.

Be aware that all protective goggles are not the same. Some will block anything below 400nm (the best) while many pass wavelengths down to 380nm. You can easily see this by putting on the goggles and looking at a Convoy with ZWB2 filter. If you see nothing, the goggles are blocking at 400nm. If you see a dim violet light, the goggles are (hopefully) blocking at 380nm. Shine the light through the goggles to illuminate a luminescent material to be sure they are blocking UVA below 380nm.

IF you really want to dig deep into the dangers of UVA, check this out: UV Damage to skin/eyes

I think the luxmeter isn’t meant for measuring UV, but it can still measure inaccurately. My test is about comparing the relative UV intensity of the Sun and the flashlight, not about an absolute measure so I think the luxmeter can still do the job.

Not neccesarily, depends on what spectrum your luxmeter picks up. If the luxmeter reads down to say 360nm, it reads almost all the output of the flashlight and only part of the sunlight’s UV (that goes down to 300nm at least). So it over-reads the flashlight then, could be too much for even a rough comparison, we do not know. There’s nowhere to be found (except do difficult spectrum measurements yourself) what UV is read by the luxmeter, the manual will always tell you that it follows the luminosity curve so it should not read anything below 400nm, still cheap luxmeters do.