incredible headlight

[Windscale]

I was referred to this item:

http://www.instructables.com/id/Ultimate-Night-Vision-Headlamp---500+-lumens-with-/

I can only say WOW.

 

[NA8]

Love the heatsink

 

[Offroad'Bent]

What's the thought about the claim that blue light is better for night vision?

 

[Gaffle]

What's the thought about the claim that blue light is better for night vision?

I read about this awhile ago. I can't remember where I read it, but 2 guys were going at it with night vision specs. Like 2 people with a lot of knowledge on the subject going at it. "This can't work because it will eat up this chemical your eyes store as it gets dark. No your wrong that chemical content blah blah blah" is now the conversation went.

Even if it is cyan, a light that bright has to destroy some night vision. All of the night vision lights I have seen have red filters.

EDIT : Why would you want 4 emitters if you are worried about night vision?

 

[TorchBoy]

1. That's a really neat photo. Must remember to get some smoke when I take pics of my own headlamp mods. I have a heatsink not unlike that one just waiting...

2. The rod cells in our eyes - the nightvision ones - are most sensitive to cyan light.

3. There's no way that monster is a nightvision headlamp. That bright, it's going to completely wreck all the wearer's nightvision and leave him exclusively using day/colour vision. (And being that end of the spectrum and that bright there might be some glare and scatter to worry about too.)

4. It can't imagine monochrome light being very pleasant to use. Better to have gone for white LEDs IMHO... Actually, that would be the main difference to something I'm planning.

5. I see it's a year old. I wonder how he'd do it now.

 

[Offroad'Bent]

I don't think he meant that the light preserves night vision, just that the Cyan tint was optimized for best night vision ie gave the best visibility in the dark for the same lumens.

While it sounds reasonable, I'd like to know if the Illuminati agree- anybody do any testing with the same powered Cyan vs white lights to compare? This is one case where beamshots won't do it.

 

[chris_m]

Oh no, not this one again! Comes up on here (and elsewhere) regularly, and every time we point out the same flaw with his theory. Torchboy pretty much has it: the issue is that he's suggesting it optimises night vision by being the colour that the rods in your eyes are most sensitive to. However as Torchboy says, the amount of light that is producing will cause your rods to shut down and you will be just using your cones. The giveaway is that you can see the colour of the light, and as rods only give you monochromatic vision, it means it can't be them you are using. Since you are using your cones, as for normal daytime vision, lumens is the correct measure to use for brightness - the more lumens, the brighter it will be, whatever colour it is - his 2.5 times multiplication factor simply isn't valid.

 

[Offroad'Bent]

Thanks for the detailed answer. Got it!:twothumbs

 

[TorchBoy]

his 2.5 times multiplication factor simply isn't valid.

:twothumbs Great explanation.

The only place when the idea would work is if the light is too faint to be able to make out any (or much) colour. Then the night vision cells would be working, and you'd be making light as efficiently as ever you possibly could. I'm thinking star light, no moon, but it might not have to be that dim. Maybe that's where the testing comes in. :naughty:

What he could have done is use green instead of cyan, since day vision is most sensitive to that colour, but like I said, monochrome light is a pig to work with, and the reason we don't use low pressure sodium vapour lights in this part of the world any more, even though they are super efficient. So what for efficiency, I say. I'd rather be able to see well.

OK, rant off. :laughing:

 

[chris_m]

Glad to see you understood that - I thought it was actually a bit woolly!

Green might optimise things for day vision, but the thing is that lumens as a measure take account of the eye's sensitivity - a 100 lumen green LED should look exactly the same brightness as a 100 lumen red LED. Therefore it's as simple as getting the LED with the highest lumen output, whatever colour that may be, and last time I looked the highest output LEDs just happened to be white!

 

[TorchBoy]

Yeah, but lumens isn't the same as efficiency. More lumens of green light than red light can be produced for the same amount of input power. To get the same lumens in green and red, more power needs to be used making the red light. Far infrared light? No lumens, since we can't see it at all, no matter how much power is used. I think efficiency was the headlamp maker's aim.

 

[PJD]

What's the thought about the claim that blue light is better for night vision?

In a nutshell, anything in the blue/green spectrum will DESTROY your night vision. A lot of manufacturers that market lights that are designed for hunters and outdoorsman like to put on their packaging (...and I've seen it many times) "green LED's for preserving night vision". This is absolute marketing hype, and it's absolutely WRONG!

The misnomer that green light is good for your night vision came from a couple places. First of all, the display on a lot of night vision devices, both military and civilian, is green. One of the reasons for this is because since your eyes are so sensitive to color in the green/blue spectrum, having a green display on night vision devices helps you to pick out details better on the usually grainy display of night vision devices. But once you take off the night vision device, your OWN night vision is totally shot. Since your eyes are so sensitive to green, your pupils constrict more when viewing green light, making the return of your own night vision a much slower process.

When you're using red light to actually view things at night, since your eyes are so much LESS sensitive to red light, your pupils do not constrict nearly as much when using red light. As a result, your own night vision returns MUCH faster after the red light has been turned off.

Green light is better for actually VIEWING things at night since your eyes are so sensitive to it, but for preserving YOUR night vision, red light is, has been, and always will be the best. Hope that helped...

PJD

 

[PhantomPhoton]

Well I don't find it very impressive.
4 Q-binned Crees can surpass 500 lumens at under 8 watts... in white light.

Second this imo whole night vision garbage associated with teal/cyan color is nothing more than buzzword for selling stuff to people who like to dress up in BDUs and play army.

The NVG (night vision green) designation is not for preserving night vision. It gives decent color rendition without being a big, white, "shoot at us over here" giveaway. Looking through a night vision goggle destroys natural night vision anyway, so there's no need to preserve night vision when don't have it anyway.

Furthermore I have heard claims that NVG doesn't show up on night vision equipment very well. So it might further enhance stealth versus an incandescent or red LED light. I only have a cheap gen 1 night vision monocular and no cyan LEDs atm so I haven't been able to test this myself. I'd love to hear from someone who does know.

 

[chris_m]

Well I don't find it very impressive.
4 Q-binned Crees can surpass 500 lumens at under 8 watts... in white light.

You're talking about now - even my P3 bin Cree triple I was building when that article came out a year ago was pretty close to 500lm at 8W!

PJD - your comments about pupils contracting isn't quite right (pupil response is fast enough to recover night vision pretty fast if that was the only problem). The issue is that cyan light destroys the chemicals in the rods which makes them work, and it takes quite a while for those chemicals to build up and get your night vision back. Rods aren't sensitive to red light, hence they stay loaded with the chemicals which make them work and you pretty much retain full night vision when you switch off your red light.

 

[chris_m]

Yeah, but lumens isn't the same as efficiency. More lumens of green light than red light can be produced for the same amount of input power.

In theory, yes. In reality check the specs of green and blue XR-E LEDs.

 

[PJD]

Rods aren't sensitive to red light...

Rod sensitivity and pupil constriction/dialition times are actually quite relative to one another, but you are absolutely right. Chemical recovery time IS the primary factor. Years ago when I was an instructor taeching basic classes on NVG's, I'd use the "constriction/dialation" thing as an example just to simplify things.

PJD

 

[TorchBoy]

In theory, yes. In reality check the specs of green and blue XR-E LEDs.

:laughing: Of course. That's why we don't have white LEDs made from RGB dice. The green ones just don't cut it (yet?).

 

[jeffosborne]

But, but, but...

For all the critics of Dan's Instructibles headlamp, I must chime in to say that I found that piece to be very inspiring with regard to building uncommon lights.

Also, Dan's LED current regulating circuit (not use in this headlamp) is one that I have used over and over to power up high-test LED's.

Cheers to all!

Jeff O.

 

[TorchBoy]

But, but, but...

For all the critics of Dan's Instructibles headlamp, I must chime in to say that I found that piece to be very inspiring with regard to building uncommon lights.

Also, Dan's LED current regulating circuit (not use in this headlamp) is one that I have used over and over to power up high-test LED's.

Cheers to all!

Jeff O.

He's solved the problem of how I get an adjustable angle on my still-in-planning headlamp without me even having to think about it. Yay! :thumbsup:

But I stopped using that sort of current regulator circuit when KD and DX started selling AMC7135 boards. All technology moves on, and I'm OK with that.

 

[mofiki]

Well, it cost me about $70 but I actually built this thing and tried it. I mounted it to the handlebars of my mountainbike and went out two nights in a row. I think what the whole thing was just an experiment, nothing more. It was misleading in a sence because of the headline but it was interesting to actually use it and see how it worked. Over time, 15 minutes or so, my vision did adjust to the light and it seemed as though I could see better and it did seemed to get brighter. The weird thing was when I ended my ride and got back to the van and the inside lights came on all I saw was red. It distorted the true color of all the road signs to the point that some seemed totally foriegn. But it lit things up pretty well and I was able to ride just as fast as I normally do with a 20W halogen light source. I don't want to get into the arguement about the science involved but I just wanted to give my .02 cents about actually using it. It was pretty cool but I would rather still use white light to get around.