Cybertool lite: New LED?

[RedRamage]

A while back I had a cybertool lite.  I had two issues with the light.  First the switch kept turning on in my pocket, which wore out the batteries might fast.  But even more annoying was that the light just wasn't that bright.

But it was probably 4 or 5 years ago that I had that knife.  I thought I heard/read that Victorinox was upgrading the LEDs, but I don't know if that was just the 58s or if it included the 91s.

[GigaHz]

All of my CT lites have a fairly bright white LED. The switch is easily turned on in your pocket.

[Neil]

The 58mm line of course got a bump to white LEDs with a boost circuit but as far as I'm aware the CT line is unchanged.  I did try a few years back swapping the LED for one that was supposed to be more efficient but frankly I couldn't see any difference 

[Syph007]

This thread is making me want to mod the circuitry and LED from a Fenix E01 into a SAK scale.

[Neil]

It'd work 

[dks]

I use a midnite manager and the light, red, is pretty pathetic really.
Allegedly the red was better for eyes adjusted to the dark (BW vision).

A mod would be welcome!!

[turnsouth]

Allegedly the red was better for eyes adjusted to the dark (BW vision).

Actually what happens is that most light excites the nerves between your brain and your eye, and even when the light is gone the electrical impulses keep moving back and forth from the eye to the brain. This is why you can see a camera flash for a few minutes, or a quick look at the sun last for a while, or why you loose your adjusted night vision after seeing white light. And for some reason the rods in your eye are not very sensitive to red and you do not loose your night vision after looking at it. Also bright white light breaks down the rhodopsin fluid in your eye, but this comes from looking at extremely bright light, and can take up to a week to recover from.

EDIT: Rule of thumb is, in order to preserve night vision use red when ever possible, and the dimmest amount of light you can to get the job done.

[Syph007]

It'd work 

Yup, but if i went to button battery I guess it wouldnt have that long a run time, and a AAA battery would take up lots of room.. stilll I kinda like the idea.  I have a sak and an E01 on my keychain right now... 

I have 2 swiss cards, the red led one is pathetic, but the white led one is quite useful.

[dks]

Turnsouth.
Possibly to do with blood being red and thus filtering red light as it goes through blood vessels, making it weaker...I used to know more..... 

[turnsouth]

Turnsouth.
Possibly to do with blood being red and thus filtering red light as it goes through blood vessels, making it weaker...I used to know more..... 

More a matter of red light having the longest, slowest wavelength of any form of visible light and thus the least energy, therefore the eye doesn't register it strongly enough to produce a compensatory reaction (the strong electrical impulses between the eye and brain).

Don't forget that the blood in the arterial pathways of the eye is blue with the oxygen removed

[Heinz Doofenshmirtz]

Visual perception actually happens to my area of specialization.  My PhD is in cognitive experimental psychology and my area of emphasis is sensory perception and psychophysics.  I did my dissertation comparing two important theories of visual attention and the predictions they make about how attention affects the search for a target object in a cluttered field.

Before I go and post a whole bunch of stuff that no one might be interested, let me know if this is something you'd like to know more about, and if so, I'll be happy to provide some info on color and dark adapted vision.

[turnsouth]

Before I go and post a whole bunch of stuff that no one might be interested, let me know if this is something you'd like to know more about, and if so, I'll be happy to provide some info on color and dark adapted vision.

My aunt was a economics professor in Philadelphia, and she use to give us a similar warning before she spent the next six hours explaining a money related topic

[RedRamage]

Before I go and post a whole bunch of stuff that no one might be interested, let me know if this is something you'd like to know more about, and if so, I'll be happy to provide some info on color and dark adapted vision.

As thread creator, I hereby grant permission!

Actually I'm just curious so I wanna know even if I wasn't the thread starter.

[RedRamage]

This thread is making me want to mod the circuitry and LED from a Fenix E01 into a SAK scale.

Well this does bring up an interesting question... why hasn't there ever been a LED light in the scale of a larger SAK?  I think the larger scale on a 91 would allow you to easily be a LED in there AND not lose the tweezers or toothpick.

[enki_ck]

This is a interesting article regarding the red light and night vision myth.

http://stlplaces.com/night_vision_red_myth/

[Heinz Doofenshmirtz]

Okay, here goes... You have been warned...

We have two primary modes of vision, photopic and scotopic.  Photopic vision is normal daylight or high light levels vision.  Sometimes it's called 'cone' based vision because those are the photoreceptors that are used for it.  At typical daylight levels, the intensity of the light is too high for the rods, and they simply shut down and stop working as they are six times more sensitive to light than cones are. 

As light levels decrease, we transition from photopic to scotopic, or rod based, vision.  Rods are much more sensitive to light and are most dense in the peripheral areas of the retina.  In fact, there are no rods at all in the macula and fovea, the center of the retina where we have high acuity visual perception.  Rod are also color-blind; their input does not get processed through the parts of the brain that process color information.  So, a simple test to find out if you are truly dark adapted is that if you can see the color in the light, you're not in scotopic vision, and you're not fully dark adapted.  There is an exception to this, however, in that even when dark adapted, you can still see the colors of stars in the sky.  This is because the point source is small enough that it can just breach the photopic boundary, but it is not enough overall light to undo dark adaptation. 

Cones are differentially sensitive to different wavelengths in the visual spectrum.  Long wavelength cones (red) are maximally sensitive at about 575 nm, medium (green) cones are maximally sensitive at about 515 nm, and short wavelength (blue) cones are maximally sensitive at about 460 nm.  Rods are maximally sensitive at around 500 nm.

The reason red is used for night vision is that a true deep red is about 660 nm which is right around the upper boundary of the L cones but well beyond the upper boundary of the rods, so they aren't activated by a red light, thus preserving their responsiveness and sensitivity when dark adapted.  However, most 'night vision' lights that are on the market today are not true deep red night vision lights.  The only one that I can think of that qualifies is made by Orion, an astronomy instruments company that uses LED emitters that are 660 nm.  All others use a wavelength of about 620 which is not technically a true deep red, and so they do have some effect on the rods when used, reducing dark adaptation.

For true night vision preservation, red works best.  However, one of the consequences is that the part of our visual system that encodes fine detail and allows us to do things like read is cone based, not rod based.  So for someone who is truly dark adapted, reading in most situations using a light that is truly low enough to preserve scotopic vision is impossible. 

If you want to preserve night vision and still be able to do things like read a map, you need to use one of the 'night vision green' (NVG) lights that are out now.  They have a wavelength output around the 500 - 505 nm that rods are maximally sensitive to.  As a result, you can use an NVG light at lower intensities and still preserve night vision than with a red light.  An additional benefit of NVG lights is that they are very close to the wavelength the green cones are maximally sensitive to, so if you want to do things like read a map, you can increase the intensity to get you to a point where you're at the photopic/scotopic transition (called mesopic) which will then activate what is called the parvocellular ganglion system in the retina, which allows high acuity vision in the cones for things like reading and seeing fine detail.  But keep in mind, you have to be careful about this, and if you make the light too bright, you'll lose dark adaptation.  If you can see the color, you're not in rod based vision.

Also, one reason the military has gone to NVG lights instead of the traditional red lights is that red lights are close enough to IR that they light up an IR scanner like a Christmas tree and readily give away your position, making you an easy target.

So, in sum, if you want just to preserve dark adaptation, red is best.  If you actually want to be able to do things like read and write or anything that requires acuity while dark adapted, NVG is your best light to use.

[turnsouth]

Good stuff

[Heinz Doofenshmirtz]

Just out of curiosity, has anyone modded the LED in one of these?  Please forgive my ignorance in asking about this... I don't know what kind of LED they have in them at all, and I'm assuming it's going to be something like a 3mm or 5mm one like you find in most cheap LED flashlights. 

In either case though Nichia does make some 3mm and 5mm HCRI 119's if IIRC, but I could be wrong of course... 

Just think, a totally sweet tool made even better with an HCRI emitter in it!