Red dot sights are now the standard aiming tool on most defensive rifles and become more and more popular on handguns. But how do they work and why should they be more popular?
Today we are going to be looking at how red dot sights function and why they are a better alternative to standard iron sights.
What is a Red Dot Sight?
The concept of a red dot sight, some times called a reflex sight, has been around since the 1900s. There were various experiments and models that used everything from ambient light to batteries in order to power the sighting dot within the optic itself.
It wasn't until 1975 when Aimpoint released their initial red dot “Aimpoint Electronic” that we started to see the red dot styles we know today.
At its core the red dot sight is a housing, similar to telescopic sights and other magnified optics, but without magnification. This allows for the sight to be mounted to the gun with all of its necessary electronics and produce the sighting dot consistently.
How do they work?
Like all things electronic there's a little a bit of magic that goes into the red sight. This isn't an over statement. Red dot sights use a particular tool of early illusionists and stage magicians to produce the red dot in the center of the sight.
This tool is referred to as the Pepper's ghost effect which is a technique that allows for things to appear in the viewer's vision without actually being there. This is done simply by bouncing light off of a piece of glass.
This light can be anything as long as it bounces correctly. In regards to the red dot sight this light is supplied by a light emitting diode (LED). Within the standard configuration for a red dot sight a small spherical mirror is angled to reflect the LED.
This mirror is also silvered to only reflect a specific visual wavelength, which in most cases is red. There are other colors available for some optics but red is the predominant color since it stands out in more environments and is better picked up against a green background.
Now the dot itself is deep red, specifically the 670 nanometre wavelength of red. This makes it easier to project because it is a very bright version of red and it works well with dichroic coatings. These coatings play well with this particular red because it is near the end of the visible spectrum which makes it easier to reflect.
Controlling the size of the dot is done by a small aperture in the sight itself. This can be special glass or metal depending on the system. This simplifies the entire design which adds to the dependability and reliability of the system.
How Long Do Red Dot Sights Last?
How does it add to reliability? The LED is a solid state system and doesn't require much power to run. This means the battery life of red dots can be hundreds to thousands of hours depending on the battery and brand of sight. This is aided by the simplicity of the dot itself. While complex reticles do exist for red dot sights many opt for a singular dot. Since the LED does not need to be a specific complex shape to be made a simple reflector can be used, which is easier to manufacture.
Are Red Dot Sights Accurate?
This reflector system means that the image seen in the optic itself is less likely to feature blurring or distortion like sights with cross hairs and magnification.
The next aspect of the red dot is the generally lower rate of parallax. Now parallax exists in all optical systems, be they red dots or magnified optics. This is because light is bent or modified in some way when it passes through glass.
What this means in practice is that a level of distortion occurs when looking through the optic. This distortion can slightly shift the image of the user. In quality red dots this is less than noticeable.
However the parallax still exists. And it is magnified when multiple layers of glass are introduced, like those individuals with corrective lenses and protective eye wear. This will again be offset by quality optics but it is still a consideration.
To offset these parameters red dots generally have a maximum focus distance by centering the dot in the optic. This is the sight's optical axis. Combining the axis with a special LED and an optical collimator results in a definite area of focus for the reticle. This distance ranges ideally from 25 to 50 yards and only applies to collimated sights.
Other sights use a two lens or double lens system. This compensates for the divergence of the optical axis with the movement of the eye. This relatively means that the dot is aligned with the sight itself and doesn't compensate for parallax errors that might occur.
How Red Dot Sights help the shooter.
Traditional sighting systems, iron sights and magnified optics, add more complexity to the shooting of a firearm. Iron sights require the eye to line up the rear sight with the front sight and the front sight with the target.
This is hard to do, so the general practice is to focus on the front sight and superimpose it on the target. With a red dot sight the iron sights are removed from the equation and replaced with a singular dot. This dot is placed on the target and “looked through” while keeping the target more in focus.
This simplification of the process allows for better accuracy and speed while allowing for a wider variety of environments for it to be used in. These range from low light to broad day to even night vision use.
There are some draw backs and additional benefits to red dot sights. While this is less of a problem on rifles and other long guns, on pistols the presentation of the sight can cause certain red dot models to cause “fishing” for the dot.
This merely means that the dot is aligned with the sight itself and the shooter has not presented the gun in a way to put their eye inline with the appropriate visual axis for the sight. This can be overcome with practice and actually helps ensure proper body and sight alignment. The presentation of the iron sights can also aid in creating a proper alignment, giving the end user a point of reference before they “find” the dot.
Another benefit of the red dot sight is eye relief. Eye relief is simply the measurement used to determine the field of view one has when using a magnified optic. Since red dots do not have magnification this means there is no need for eye relief and the sight may be placed any where deemed convenient on the weapon without sacrificing vision.
This also means that the sight does not need to be extremely close to the eye. With magnified optics that require very short eye relief there is a hazard that the optic is too close and will hit the user when the gun recoils. The lack of magnification allows for greater areas of eye relief despite it being a non-issue for red dot sights.
Another benefit is spatial awareness. The red dot sight allows for both eyes to be open when using the sight rather than fully or partially closing an eye. This closure method used to be recommend when using magnified optics in the past, but is now being replaced with the use of both eyes or partially closing one eye.
Having both eyes open allows for the user to easily see what is going on around them and to track targets as they moved. This is why early Aimpoints were marketed as hunting tools since they allowed for the tracking of animals as they tried to evade the hunter. This allowed for more accuracy and increased speed unlike traditional magnified optics where tracking the target could cause the scope to impede the vision of the shooter.
This speed and accuracy makes it ideal for more dynamic situations like hunting, competition, and law enforcement/military applications.
Red Dot Sights Conclusion
Red dot sights are absolutely force multipliers when it comes to firearms. They make aiming easier, consistent, and overall more effective than with traditional iron sights, if they are properly zeroed.
The advancements of sighting technology over the years have taken old parlor tricks and applied them to the modern world of firearms technology. These simplistic designs take a lot effort to build but once they are done right they are easily applied across the board.
As red dots were developed we saw designs reminiscent of early magnified optics then minimalist designs with open emitters and finally a return to close emitters. Each of these different variations adds to the overall knowledge of which red dot sights work for different environments and purposes. And with each new addition, the red dot sight is solidified as necessary gear for modern firearms.
With this solidification comes the new learning curve of using red dots. Which in practice is easier than expected (model dependent) but still has to overcome the conventional wisdom of decades of firearms training where the technology was either not available or didn't exist.
Red dots are a significant leap forward when it comes to basic sighting systems and with the addition of low powered variable optics create a wide variety of sighting options for the individual that are significantly better than traditional irons.