How do red dot sights work?

 

Red dot optics are non-magnifying sights that generate a dot shaped reticle by directing an off axis LED at a tilted concave reflector, typically coated to only reflect one color, producing a green or the more common “Red Dot” in the sight.

 

The angle of the LED and the doping of the reflector ensure little to no light signature. While the size of the image/dot projected onto the glass, and reflected back to your eye, is controlled by adjusting the aperture in font of the LED.

Why use red dot sights

Ok to start with this sight does not contain much. No holograms, or arrays of lasers, and with only the solid state LED, it also does not consume much in the way of power use. That being said, this “Keep It Simple” device is reliable, cost effective and has a ridiculously low learning curve.

It is almost parallax free, with the projected dot remaining aligned regardless of the eye position, aiding accuracy and reducing the time spent aligning sights.

The adjustable reticle superimposed over the field of view makes red dots extremely effective in short and mid range distances. Smaller dots are more suitable for further distances; as they will cover less of the target. Larger dots at shorter distances; for quicker target identification.

It should come as no surprise to hear that they are also fairly popular. Often seen used, not only by the police and military, but in hunting, target shooting, air rifles/ pistols, crossbows and outside of firearms, such as telescopes, cameras and long range audio devices.

Advantages and Disadvantages

Before buying  red dot sight you might want to know what to generally expect from these devices, here’s a quick run down of the benefits and limitations:
Pros
  • Easy to use
  • Price
  • Size
  • Many manufactures
  • Parallax free
  • Compact
  • Power use (battery life)
  • Adjustable reticle
  • Non-revealing light signature
  • Versatile
  • Speed
  • Night/low light conditions
Cons
  • Smaller field of view
  • Electronic
  • Many manufactures

When were red dot sights invented, who invented them

The technology itself has been around since 1900, with the precursor to red dot being the reflector sight, also known as reflex sights.

Red dot sights as we know them today, using a LED instead of illuminating a reticle, were invented in 1975. Based on a design by John Ekstrand, the Swedish optics company Aimpoint launched it as the first electronic sight and under the name of the “Aimpoint Electronic”.

With only the combination of a curved mirror and a light-emitting diode, this streamlined apparatus boasted an operating time of up to 3000 hours. Over the years improvements, in low power consumption of the LEDs, have incrementally built up to where now newer models can be ran continuously for years without being switched off.

Who makes red dot sights

The simplicity of the design has resulted in a relatively low barrier of entry into the red dot sight market. Today there are many manufactures each offering more than one model of red dots, but the familiar names still appear in most of the Top red dot sights lists.

Aimpoint

Since the first Aimpoint electronic, Aimpoints line of red dot sights have refined adding features such as performance improvements and band-pass coating to expand the sights compatibility with night vision devices. The pedigree of aim points red dot sights can be seen the fact that Aimpoint has been providing optics to the U.S. Military for over 20 years, and currently supply the CompM4 optic designated the M68 Close Combat Optic (M68CCO).

Bushnell

Bushnell Offer a wide range of optics, as well as red dots they also make reflex sighs, holographic sights and night vision monocular. There red dots sights all come with a lifetime warranty and are made to work with a massive range on guns, from rifles and pistols to shotguns these rugged shockproof units work well and make for a light weight solution.

Vortex

Vortex sights are durable and very reasonably priced, making them a popular choice for beginners, or those on a budget but still want a parallax free red dot sight. They tend to have a battery life around the 5,000 hour mark, plus an auto shut down function that extends that even further. Vortex also make very respectable rangefinders, spotting scopes and binoculars, that have been well received in the hunting and archery communities.

Sightmark

While maybe not as well known, Sightmark red dots are well tooled and high quality. Using a double pane lens to reduce parallax, they are very functional having a quick release mechanism on the rail mounting and work in combination with night vision devices. Many models are customizable, offering multiple reticles and input settings so you can further adjust and fine tune the sight.

The manufactures above are by no means a comprehensive list. But are among the forerunners in the red dot sights and optics field

How to sight in – zeroing a red dot sight

Sighting in, or zeroing, a sight is the process taken to align the sight with the weapon creating a predictable point of impact. This is largely achieved through adjustments made for windage and elevation.

It is recommended to begin with your sight on its default settings. This can be achieved by adjusting the windage and elevation settings both to the center point or to “Zero”, and then making the appropriate alterations. Sights are said to have been sighted, or zeroed-in, when they can accurately line up to the point of impact.

Another important element when sighting a red dot is when mounting the sight itself. Ensuring the sight is aligned and straight when first mounting will reduce the amount of smaller corrective adjustments that need to be made later on.

Check out the video below for quick overview

How to adjust red dot sights

While the controls that adjust for elevation and windage on red dot sights will vary by manufacture and model, some not having any at all, the underlying principle stays the same.

Adjusting for windage is moving the point of impact on the horizontal plane, left and right of the center point. Adjusting for elevation is moving the impact point vertically. This can be done through the use of electronics and/or manually during the fitting and sighting of the scope.

Whether adjusting sights on rifles or handguns, the steps are the same (given you have zeroed iron sights on rifle). Once the sight has been mounted adjust the red dot optic to the point where the dot is just above the front iron sight, this is as known as lolipopping as seen in the graphic below.

Red Dot Sight Lollipop

FAQ

You can expect many red dots for AR rifles, or inexpensive red dots when on a budget to cost around $100. But the best on the market to have a price tag 3x to 5x more. Overall red dot sights are not expensive, especially when considering the advantages and disadvantages above.

Red dot sights are relatively low cost when compared to other entry level electronic sights. What you are actually paying for is the quality of the glass optic; parallax free weather resistant clarity. The shockproof stability during operation over time; long life electronic components and a build quality that handles recoil but still allows for precise adjustments to be made.

Yes, real red dots are available on the consumer market. Although it remains up for debate whether sights need to be; completely parallax free, repeatable zero and able to complete the “box test”, to be considered real or genuine.

The box test is a repeatable zero accuracy test performed to assess the mechanical stability of the sight adjustment and attachment. The weapon is fired, adjusted an arbitrary number of clicks, fired again, adjusted the same number of clicks in the same direction, fired again…and repeated adjusting for windage and elevation in both directions. When this is done ideally the impact should form a box with straight lines.

The latest generation of red dots offer impressive optical resolution, brightness and are very robust; designed for continuous use and to deal with demanding changing conditions – anti-fog, resistant to water and dust.

Optical sights themselves are legal, although some night vision and other audio surveillance technology may be restricted in your region so please check and abide within the laws of you Country/State/City when buying and using any optical or audio enhancement devices.

Yes red dots work at night. The lens is designed to reflect the same spectrum as the LED, which itself can usually be adjusted actively or passively, and so work in all lighting conditions.

Keep in mind that, when you need to use them in complete darkness, most sights are night vision compatible; allowing a night vision device to be mounted in conjunction with holographic or red dot sights.

Yes red dots sights work in daylight. The higher the intensity of the dot the higher the visibility will be during brighter days. The same can be said for using a dimmer dot in low light settings, again ensuring visibility of the dot but also preserving night vision.

Yes a battery is required to power the light emitting diode housed within the sight. There are some,  but not many, models that use rechargeable batteries. But in most cases the batteries are able to be replaced by user themselves.

There are extremely low powered LEDs available in some models that boast a battery life of around 10,000 hours.

Lowering brightness settings may also extend the length of time a sight will run in-between charges or replacement.

Standard red dot sights are non-magnifying, the red dot reticle is reflected on a clear screen which is usually coated to better reflect the LED. Although magnifying devices do work well when mounted in conjunction with red dot sights.

All red dot sights have some parallax. No sight is completely parallax free, except for maybe a laser sight. However the vast majority of top of the line red dot sights are designed to compensate for parallax. Reducing it to point where it is not noticeable at mid ranges, and negligible at close ranges; where the parallax deviation is usually at its worse.

Red dot sights will accurately display a clear dot reticle in the viewport and reduce the time needed to aim. The accuracy of the shot itself will be down to; how well the weapon has been zeroed, ensuring the sight is stably fitted; providing a reliable impact point, and the shooter.

Red dots were not used in WW2 but the ancestor to them, the reflex or reflector sight, were. They were mainly used on the larger weapons such as anti-aircraft guns, anti-tank guns and fighter aircraft.

There are red dot sights currently on the market which offer multiple different reticle options. A common configuration would be 1. A single dot. 2. A single Circle. 3. Circle and dot combination.

A number of red dots sights come with a lifetime warranty. One of the manufactures mentioned earlier in the page is Bushnell who offer a life time warranty on wide range of optics.

Red dot sights certainly provide a clear easy-to-see perception of the target, and are able do this well over distance and quickly.

As they get smaller, and more powerful, the benefits to using them in competitive settings have become apparent by their high adoption rate. Optical sights also offer advantages over traditional iron sights for those with poor or ailing eyesight.

However one of the drawback to the miniaturization of red dots is the equally rising complexity of the installation. Similarly the large choice in manufacture and model can result in an overwhelming number of units to pick from.

The most popular red dots manufactures seen used by the military are EOTech and Aimpoint. As mentioned above in the page, Aimpoint currently supplies the U.S. Miliitary with the CompM4 optic, designated the M68 Close Combat Optic (M68CCO).