Why "Red" Dots?: Just fun discussion...

[LooseGrouper]

Why do scopes with illuminated reticles use the colors they do? Most use red. A few use green. At least one that I know of (Trijicon, I think) uses amber.

I think someone should make an illuminated reticle scope in bright blue. Blue is the most prominent color in the visual spectrum, and is the easiest color for human beings to see. Red (and to a lesser degree amber) are on the fringe of the visual spectrum. Green is more centered, but it seems like it would be more likely to "disappear" in foliage.

Another point has to do with color vision. As I understand it, there are three different types of color sensing nuerons in the eye structure: Beta (blue), Gama (green), and Rho (red). These basically sense the levels of their specific frequencies of light and work like the cartridges of a color printer to "mix" the right color. Unfortunately, the most common form of colorblindness is caused by a deficiency in the red and/or green cells. This causes the eye to have a low "color resolution" when disinguishing between items that are red and green (or the result of mixing red and green: brown). If to much of one color is present (for example, a thick wall of green shrubbery) a small amount of the other color (for example, a bright red cardinal sitting in the shrubbery) would be undetected, or at least less prominent. It seems to me that this could lead to a red reticle getting lost against the green backround of foliage. Green could get lost in the same way. That's why I think a blue reticle would be great...unless you have to shoot into the sky for some reason.

Okay, I know this is kind of foolish. I'm sure all the top optics companies have put millions of dollars into R&D to determine the best color. I just wanted to see if anyone has thought about this besides me...

 

[PromptCritical]

Those a called "cones"

As I read it, this nost visible color is green. Nevermind blue it is.

http://www.photo.net/photo/edscott/vis00010.htm

Humans have trichromatic vision, many birds have quad. Four types of cones, allowing them to see into the UV, or that space between green and blue. There was some research into human infrared vision during WWII but that ended with the development of infrared devices. Interesting stuff.

 

[iluvG.R.I.T.S]

I never knew of the amber and green ones.I didnt think it was a matter of "choice" I just thought it used a laser which was always red.I wouldnt mind a blue one.

 

[Technosavant]

Actually, I don't believe that blue is the easiest color to see... in fact, from what I understand, it is the exact opposite. Red also is a less energetic color, meaning that it takes less power to create a red light than a blue one (longer battery life).

An actual scientist would be more than welcome to correct me on this one.

 

[PromptCritical]

Some people can also see further into the violet spectrum than others.

 

[boofus]

I think a blue reticle would not be good for dark areas. Blue is supposedly the best color for night camoflage, black stands out too easily, but shades of blue blends in better in low light.

 

[taliv]

yeah, that's why they paint school busses blue, and fire engines and ambulances. and emergency exit signs.

 

[Kor]

You could easily lose track of a blue dot against the sky, or water...not that you would be doing any responsible target shooting at aerial or floating targets, or at targets skylined at the top of a ridge/berm, but maybe while hunting waterfowl.

You could also easily lose a green dot against foliage, depending on the exact color and stage of growth/time of year.

Yellow could also be lost against dry, dead grass or desert sands.(However, Trijicon put a bright amber-colored reticle in their CQC scope, which was a logical choice given the urban CQB use it was designed for.)

Bright red seems to be the color that contrasts most highly against most natural surroundings - apart from the red leaves of autumn, rose bushes, etc.

 

[Preacherman]

I wanna rainbow dot!

 

[Jeff White]

Amber washes out in bright light. I much prefer a red reticule to an amber one.

Jeff

 

[LooseGrouper]

Preacherman might be on to something...

How about a green 40 moa circle containing a red set of cross hairs, and at the center a blue 4 moa dot. All bases covered

Okay, I'm an idiot...the first step is admitting that you have a problem...

 

[boofus]

Well fire engines, ambulances and emergency exit signs don't go driving around in the bushes at night time with their lights off either.

 

[Caseless]

From the catalogs I've read. Manufacturers use red for daytime, green for nighttime. Some red dot scopes thus can be switched between red and green dots.
Amber dots for twilight/dawn?

 

[jefnvk]

I got one that swaps between red and green, FWIW. It broke once, and both the red and green were shining at the same time, making a yellowish color. Wish I wouldn't have fixed it, but it wouldn't turn off. I liked the yellow/orange.

 

[chevrofreak]

"I just thought it used a laser which was always red."

I used to think they were lasers, but they aren't. You arent seeing a projection, you're actually seeing a reflection, of a mask thats placed over an LED in the shape of the desired reticle.

 

[Ukraine Train]

Yep, they're LED's. I think also some LED colors are easier/cheaper to make than others for whatever reason, maybe just because red is so widely used that it's cheaper due to volume.

 

[CleverName]

Due to a lot of boring technical details, blue LEDs were invented last, and used to be more expensive.

I thought that sickly yellow color that some new fire engines are painted is supposed to be the one people respond to best.

Red does tend to stand out in natural surroundings, though.

EDIT: spellin'

 

[LiquidTension]

I think the answers have already been mentioned:

When one looks at the visible light spectrum, red is on one end (typically the "left") while violet is on the other. Red light has a longer wavelength than blue, therefore it requires less energy to produce. Think of trying to hit something once every second vs. once every hour - the longer the interval, the less energy required. This is why higher end red dots like the Aimpoint Comp series have such a long battery life. Well, that and the super efficient battery technology whatchamacallit stuff. If they were displaying a blue dot, battery life would be shorter. Yes, I realize that the Comp series lasts for several years, that's not the point.

The next thing to consider is the visibility factor. Why do you think stop lights, road flares, and brake lights are red? Red is highly visible to the human eye while not being "bright" per se. This is also one of the reasons that alarm clocks are often red - that end of the spectrum does not cause discomfort in the human eye. Ever looked right at a black light? Yeah, not comfortable.

As for optical sights, what color do you encounter the least often in nature: red, green, or blue? As mentioned before, green = foliage, blue = sky and water. Red = ...what? Unless you're gonna be fighting in a field of roses, red seems to be the logical choice. The chances of fighting in a red clay environment at sunset are pretty low when compared to the chances of fighting near foliage, water, or the sky.

For what it's worth, yellow text on a black background is easiest for the human eye to read

Pardon the typos, I'm tired.

 

[chopinbloc]

red diodes are more common so they're more common. cause and effect eating each other red is less energetic, etc. i have a trijicon reflex II and it has an amber dot, the lens is coated with a substance (probably gold) that reflects yellow wavelengths of light, making the image look blue through the lens and giving greater contrast to the dot. it came w/ a polarizing filter which allows the user to vary the amount of light coming into the lens without interrupting the light to the fiber optic collector. like sun glasses for your sight. the only time you come close to washing out the dot is with the brightest sunlight when you are standing in a shaded area and looking at a very bright area. then a simple turn of the filter fixes things right away. trijicon sights may be expensive, but they really are worth it.

 

[Standing Wolf]

I'd like to be able to vary color, dot size, and intensity of light.

 

[LooseGrouper]

Standing Wolf

I agree that it would be pretty cool, but from the answers I've read it sounds like it would be difficult. Changing intensity is apparently pretty easy seeing as all the optics I'm aware of have that capability. Changing reticles is also apparently doable, since Bushnell, Hakko, and probably others already have the capability.

Apparently you need to use a different color LED to get a different color reticle? Referencing chevrofreak's post about the reflective masks, would it be possible to just use a white LED (do they exist?) and then change the colors of the mask? If so then you could do it in the same manner as the reticle-changing units. On the other hand, I could see how this would make it difficult to get a crisp, bright image. There would probably be alot of bleedover from the other frequencies.

 

[CleverName]

Yes, white LEDs exist. IIRC the actual emission layer of the LED is a combination of red, blue, and green emission layers. So a white LED is actually a mixed RGB LED.

 

[IZHUMINTER]

I seem to recall reading an excerpt from one or two night-vision studies that determined red was the best color for retaining unaugmented night vision, while green provided the best contrast. Blue was seen as undesirable. While I can't seem to find where I laid those, I did find a pretty good site here ( http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html#c1 ) that might shed some light on why blue is not as desirable as other colors.

While this is especially true for night time use, the lack of distinct focus for blue objects compared to red or green objects holds true in the daylight as well.

 

[chevrofreak]

White LED's are actually blue LED's with a phosphor over the emitter diode to convert the wavelength to "white". They aren't RGB, but there are RGB LED's made that could be used to form most colors desired.

A stationary mask (meaning no multiple reticle options) and a color wheel would indeed be doable but it would add considerable size to the diode housing inside the sight, and in many sights the housing already protrudes into our sight path.

My suggestion would be a housing external to the sight body that contained several LED's of different color or an RGB LED. The light would then be channeled to the mask via a fiber optic line. This could also allow interchangeable lighting diode packs to be swapped quickly on the outside of the sight, or a fiber optic light tube, similar to the ACOG could be put in its place. Alternatively, tritium vials or cyalume sticks. Using fiber optics to transmit the light to the mask will open up a tremendous amount of options.

Power regulation circuits have come a long way and could be implemented in the sight as well. I do not know about Aimpoints CET or ACET technology, but my guess would be that it ises circuits to precicely control the power flow to the emitter, rather than it simply being direct drive or resistored.

Any manufacturers up to the challenge?

 

[LooseGrouper]

Why would the reticle have to be stationary? I think I need to see some drawings, because I can't figure out why a color wheel couldn't rotate parellel to a "reticle mask wheel" on on a nearly co-located plane. (not trying to be a wiseguy...I really just can't picture it).

Anyone know of a good place to get turorial on how these things work? I learn visually. I highly doubt it's featured on howstuffworks.com...but they do have a great tutorial on semi/full auto firearms. Nothing on 3 rd burst, though.