Red Dot Sight Optics Explained: Basic Principles

Chris G.

Understanding the basic principles of red dot sight optics is essential for any shooting enthusiast. They improve focus and accuracy through faster and more precise target acquisition than iron sights.

In this guide, we will delve into the mechanics of red dot sight optics, including its integral components, various types, and reticle sizes.

The knowledge gained here will help lay a solid foundation for becoming a more accurate and confident shooter.

Understanding the Basic Principle of Red Dot Sights

A red dot sight is a type of non-magnifying reflector sight used on firearms. The basic principle of a red dot sight is quite simple: it involves projecting an illuminated reticle, typically in the form of a red dot, onto a target. When properly adjusted, it provides a precise point of aim. Without having to sight through the firearm’s traditional iron sights, a shooter increases his accuracy and speed in firing the weapon.

Here are the basic principles of red dot sight optics:

  1. Illuminated Reticle: Red dot sights use an illuminated reticle, typically a red dot generated by a powerful light-emitting diode (LED), as the aiming point. The dot is projected onto a lens, appearing as if it’s floating in the user’s field of view.
  2. Parallax-Free Design: This means that the point of aim remains on the target, regardless of eye position or the angle at which they view the sight.
  3. Zero Magnification: Most red dot sights do not magnify the target, allowing for a wide field of view. 
  4. Adjustable Brightness: Red dot sights usually have adjustable brightness settings to allow the shooter to adapt the sight to different lighting conditions.
  5. Rugged and Durable Construction: Because they’re used in firearms, red dot sights are often designed to be durable and resistant to recoil, shocks, and environmental conditions. They are commonly used in military, law enforcement, and civilian applications.
  6. Versatility: Red dot sights can be used on various firearms, including rifles, shotguns, and handguns. They are also popular in competitive shooting sports and are employed in recreational shooting and hunting.

Parts of a Red Dot Sight

A red dot optic is made of several important parts. The parts listed below are common to all brands and models of red dots.

  • Objective Lens: Situated at the forefront of the red dot sight, the lens is where the shooter looks through. A red dot lens is often multi-coated to collect ambient light, diminish glare, intensify the brightness and clarity of the reticule, and establish a proper sight picture. The lens is usually parallax free to ensure the reticle stays fixed on the target regardless of the user’s eye position or viewing angle 
  • LED (Light-Emitting Diode): The LED generates the reticule which is then reflected by the lens.
  • Reflector Optical System: In reflector sights, the LED-generated reticle is reflected onto the lens.
  • Adjustment Turrets: Integrated into red dot sights, adjustment turrets are typically situated on the top and sides of the device. These turrets allow the user to make precise adjustments to align the point of impact with the red dot.
  • Windage and Elevation Controls: These controls allow the shooter to move the reticle horizontally (windage) and vertically (elevation). These controls are essential for zeroing the sight and compensating for bullet drop and wind drift.
  • Battery Compartment: Given that red dot sights rely on batteries for power, they incorporate a dedicated compartment to house one or more batteries. The battery compartment is often ruggedized to prevent water or dust from penetrating the electronics. Battery life of top-quality red dot sights can be tens of thousands of hours.
  • Illumination Controls: These controls are for adjusting the brightness of the illuminated reticle.
  • Housing or Chassis: Functioning as the protective enclosure for all internal components, the housing or chassis of the red dot sight is designed to withstand recoil, shocks, and harsh environmental conditions.

Types of Red Dot Sights

Red dot sights come in various types, each with its unique design and features tailored to specific applications. Here are some different types of red dot sights on the market:

  1. Tube Sights: These sights have a cylindrical or tubular shape and are enclosed within a metal or aluminum housing.
  2. Open or Reflex Red Dot Sights: These sights have an open design with a single lens and a reticle reflected onto the lens. They are often more compact and lightweight than tube-style sights. Open or reflex sights are popular for quick target acquisition and are commonly used in competitive shooting and tactical applications.
  3. Holographic Sights: Holographic sights use a laser transmission hologram to project the reticle onto the lens. They typically have a window with a three-dimensional display. Holographic sights are known for their fast target acquisition and are often used in tactical and military applications.
  4. Prism Sights: Prism sights have a fixed magnification and use a prism to project the reticle onto the lens. They are more compact than traditional scopes.
  5. Variable Power Red Dot Sights: Variable power red dot sights allow users to adjust the magnification level. They combine the rapid target acquisition of a red dot with the versatility of variable magnification.
  6. Mini Red Dot Sights (MRDS): Mini red dot sights are compact and lightweight. MRDS can be used in conjunction with other optics such as rifle scopes and night vision scopes. 

Reticle Sizes

Understanding the different reticle sizes in red dot sights is crucial for shooters to engage targets accurately at various distances. The size of the reticle, typically measured in minutes of angle (MOA), plays a significant role in target acquisition and precision.

Larger reticles are more visible and allow for quick target acquisition, but they may cover up more of the target at longer distances, potentially reducing accuracy. On the other hand, smaller dots offer increased precision at extended ranges, but they may be more challenging to pick up quickly.

It’s important to note that the size of the reticle isn’t the sole factor that affects the performance of a red dot sight. Other factors such as eye relief, target size and distance, lighting conditions, and brightness settings also contribute to the effective use of the sight.


Red dot sights are an innovative tool in the world of firearms optics, providing quick target acquisition and improved accuracy. They consist of different components and come in various types and reticle sizes to cater to different needs.

These sights are widely used in activities such as hunting, sport, home defense, and tactical operations. Understanding the fundamental principles of red dot sights is crucial for maximizing their effectiveness and enhancing shooting performance.

About the author

The name's Chris. Just a regular dude who loves firearms. I've been shooting since I was a kid. My old man taught me the ropes.

I'll never forget the first time I missed an easy shot on a buck, thanks to a bum scope. The image was fuzzier than my dog's butt. After that, I got obsessed with understanding scopes. What makes the good ones tick and the bad ones trash. After a few years and a few thousand bucks, I learned what separates the winners from the losers. Once I had a good stockpile of knowledge, I launched this site.

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