RED DOT SIGHT: The Comprehensive Guide

What is a red dot sight?

Red dot sight (called RDS) is a non-magnifying optic, usually attached to the firearm or hunting equipment. But some professional photographers also use them on their camera for capturing birds in-flight motion. Its application is not restricted to weapons only. So, if your device requires simple aiming system, RDS can certainly help.

*Note: In this article we talks specifically about the use of RDS only on the firearms.

To put it simply, it is an optic that attached to your weapon and when you look through, it illuminates where the bullets will go with a simple little dot.

It has no magnification/zoom power.

Due to its ability to place the dot (or reticule) on target in a short period of time, RDS is highly recommended for close and rapid shooting, but it is not really good when use for precision shooting.


The Operating Principle

To understand how the RDS operates, we need to know what types of projection system it use.

Firstly, you need to know that red dot sight can be divided into two types, which are:

  1. Reflex
  2. Holographic

Types of projection system

In general, reflex sight operates with a really simple mechanism – It utilizes a piece of glass that reflects an LED right onto the viewing window. And for your information, MOST of the RDS available on the market today are classified as reflex sights.


But can you guess why it’s called ‘reflex’? Let’s have a look at this explanation:

“In reflex sight, the LED emits light and is directed towards the objective lens (which act as a partially reflective mirror). The LED hits the lens, and the REFLECTED LED beam will be directed back towards the shooter’s line of view”

The above explanation is self-explanatory. If you still have no idea why it’s called reflex, re-read the explanation above. (Hint: Try pronouncing the word in bold repeatedly)

For holographic, the reason behind its name should be crystal clear. Basically holographic weapon sight (or holosight) operates with a physics concept called a “Laser Transmission Hologram”. It will takes some time to explain the concept in details (and you might not interested to understand complex things etc), but I’ll try to explain in a much simpler way…

It has a laser diode, which generates a laser beam (polarized) that will be directed towards a series of reflectors where the beam will finally moves towards the reflective holographic grating that illuminates hologram of sighting reticules (the dots) that is superimposed into the viewing glass (as shown on the image).

Typically, the viewing glass of holosight has no internal reflective coating, so the hologram generated won’t alter or disturb the normal light passing through the window. You can see the target clearly while the reticule remained superimposed on your field of view.

Want to know a bit more about the comparison between holographic vs reflex? Read this article – Understanding the Differences Between Reflex Sight & Holographic Weapon Sights

Advantages & Disadvantages of RDS

Red dot sight is by far the most common attachment for guns, and why is that? It’s for a good reason – it improves accuracy exponentially while not changing the feel of the gun.

And it’s only natural to question the viability of needing a reddot scope because it’s an added expense to your gun. So why would you want one?

Advantages of using red dot sight

The advantages of using this optic as compared to the others are listed below:

  • Significantly improves accuracy & precision
  • Remains FOCUS on target & FASTER target acquisition
  • Perfect for close quarter combat/battle (CQC/CQB)
  • Precise aiming even during rough environmental conditions (eg: heavy rain or dark surroundings etc)
  • Improves situational awareness – Aim with BOTH EYES wide open!
  • Come in handy for people with vision limitation (where the application of iron sight is useless) – eg: astigmatism, short-sightedness

Note : If you have the experience using an iron sight, you already know how hard it would be to aim faster & shoot accurately just by relying solely on the iron (especially if you are just a beginner).

Using iron optic is not as simple as it might appears to be in the movies. In fact, it takes years to master. With iron, everything has to be perfectly aligned. Not only that, but you (usually) have one eye closed, giving you minimal awareness of the surroundings.

However, with the help of RDS you don’t need this meticulous alignment. It helps you to skip the hard work – just attach your RDS to your firearm, and you immediately get a more concise spread without adding on the hassles of a scope.

Of course you can be just as accurate with an iron as a reddot, but in the heat of moment, carefully aligning all the necessary elements (while having one eye closed) is a recipe for disaster.

The reticle of the RDS will always tells you where the bullets will go, regardless of the angle you’re looking through it at. And you don’t need to close your other eye to see it.

That’s really the icing on the cake.

RDS is also more effective and efficient as it allow faster aiming, can be used in any lightning condition and the user can maintain his natural view of the target and its surroundings in particular.

Can it be use on any type of firearm?

The beautiful thing about this optic is the fact that you can use it on (almost) any gun. That doesn’t mean that you necessarily want to, though.

Reddot optics improve accuracy, but not to the level that a magnifying scope does. And on some guns, you don’t really need that much precision. To touch on the point of precision, consider a shotgun. When you line up to take a shot, do you carefully aim for the center of the chest? Probably not… Sure, you align your shot, but because of how a shotgun operates, you don’t need to be perfect.

Pistols are similar – you’re using them at a closer range, which takes the need for precision out of the equation. Some people DO USE reddot on pistols though, but it’s not common.

To touch on the point of magnification – as humans, we can only see so far. If you’re trying to shoot on something at a certain distance, RDS won’t do anything for you. A red dot scope still relies heavily on your natural vision, whatever that may be – it just gives you more accuracy up to a certain distance.

The maximum aiming distance

How far we can aim with a red dot?

It’s totally depend on your eyesight. If you can see that far, then that’s the maximum distance you can aim for.

It means that if your vision allows you to see clearly up to 150 yards, then that’s the maximum distance you can target with a RDS. But if you have an eyesight problems – eg: short-sightedness, then the maximum distance is probably takes up to 50-100 yards, depending on how bad your vision is.

From observations, we found that the typical shooting range for accurate aim (without any magnification) is between 100 yards to 200 yards.

But I’ve seen people shoot with RDS accurately from 300 yards away!

Well.. We are not saying it’s impossible. It can be done provided that you have a lot of experience in shooting (and you don’t have any eyesight problem obviously). The dot size also plays a very important roles here. But for beginner, it’s totally impossible to shoot accurately from 200 yards out just with non-magnifying red dot optics.

Just keep this in mind: RDS is the best for rapid & close range shooting. If you want to shoot at longer distance, consider using a red dot magnifier or a telescopic optic (eg: riflescope).

Field of View – How wide it can covers?

It depends. Different models give different field-of-view (FOV) according to their corresponding design and configurations. For example, the HUD (or “open”) style configuration gives much wider FOV compared to tube-scope like configurations. But in general RDS has a wide FOV.

Field of view is the measure of width or angular size of the image that can be viewed through the viewing window (30ft at 100 yards, for example).

It’s important to realize that since most of the RDS has no magnification, you can aim with both eyes wide open! Thus, your actual field of view is really wide! For 0-300 yard defensive range, it shouldn’t be a problem for a red dot.

The FOV issues usually become important when it involves a magnifying scope that requires you to close the other eye to focus on long range target, limiting the view of the surrounding.

What is Iron Sight?


Iron sight example

View from the iron sight (Image Source: Wikipedia)

For those who never heard of an iron sight, here’s what it is:

Iron sight is a basic targeting system with alignment markers (usually metal) designed to assist in accurate target aiming. It usually composed of two components, a front sight positioned as a bead, ring or post, and a rear sight that is always perpendicular to your line of vision.

Iron can be divided into two types; an open sight that uses some sort of a notch on the rear sight and an aperture sight (for example Ghost Rings & Target Aperture) that uses a circular hole.

The older version of iron optics are difficult to adjust. However, they were fixed now and most of the latest iron sighting system were designed to be easily adjustable especially the rear sight for elevation and windage.

Although we currently have a modern and more reliable electronic optics, iron sighting system will still come in handy as a back-up aiming system (BUIS).

Open & Aperture Iron Optics

Types of Iron Sights: A-G: Open; H: Ghost Rings – Aperture

Understanding Co-witnessing and Its Importance

It is true that RDS are remarkable invention for putting rounds on target accurately and nearly idiot proof for reliable aiming.

However, they still have an uncanny ability to FAIL at the most inconvenient circumstances for instance when you’re hunting, during competitions, or more worse while you’re in a firefight.

This is where your iron sighting system will come in handy as back-up.

That’s why it’s important to mount them on your gun beforehand despite having an electronic optic. You can just zero the iron and ignore it until the time comes when you need them. Incidentally, the most popular way of doing this is by “co-witnessing” your iron with the red dot.

“Co-witnessing” is in effect when both iron & RDS are in proper alignment, and the aiming point for both optic line up exactly with each other.

Co-witnessing can be divided into three types;

  • Absolute Co-Witness
  • Lower Third Co-Witness
  • Rear Flip Sight Co-Witness

Watch this video for more detailed explanation on each type.

[Opinion] Which one first – Iron or RDS?

This is another one hot debate.

Should we learn to use iron first or use electronic optic first?

Most of the veterans that I’ve found said that we cannot always depend on the electronic sights. So, they are suggesting iron as your first optic.

I beg to differ. Here’s my point:

I do agree with the opinion that we shouldn’t be too dependent on electronic optics (eg: RDS), but only to a certain extent. For beginner,  it’s better to start shooting with the help of an electronically-equipped sight in order to feel the excitement and joy of hitting the target with accuracy & precision. Once you have the confidence of delivering bullets right into the target, then you can start upgrading your individual skills by trying something harder – shooting with iron sight or shoot at different angle etc.

For me, the important first thing is to build up your confidence since it can motivate you to work harder and improvise yourself to be a much better shooter in the future.

iron vs electronic

Final Word

So, what is your take on this matter? In your opinion, which one can gives the best learning curve?

If you have anything to add, please share your thought on the comment section below. We’d love to hear your advice for our beginners out there.

Our Source of Reference(s)

  1. Understanding Electronic Sights,
  2. Red Dot Sight,
  3. Steven L, Introduction to Red Dot Sight,
  4. John A. Dreyer, Facts and Figures About Dot Sights,