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The Science Behind Red Dot Sights: How They Work

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Few optics have risen in popularity quite like the reflex sight. For decades, they’ve been a staple optic choice, renowned for their ease of use, lightweight form factor, and rapid target acquisition capabilities.  

Today, they’re in use in some form by Military and Law Enforcement groups globally and have proven their worth as a durable and utilitarian optic system. Modern enthusiasts today often use them when they need performance that can’t otherwise be achieved when using traditional variable power optics.  


What Exactly are Red Dot Sights?  

In its simplest form, red dot sights are a derivative of the original dot sight, the reflex sight. Fundamentally, the two are identical in purpose, with their core differences being due to their construction and function.  

At their core, reflex and red dot sights use an LED to project a reticle onto the objective lens of the optic. The light gets reflected at the user, creating the iconic ‘dot’ reticle image. As technology progressed, manufacturers could construct the diodes in a way so they can project multiple reticle patterns such as the more popular circle dot and chevron reticle patterns. Some red dot models even feature our line of ACSS reticles There are many types of reflex sights, but not all reflex sights are red dot sights even though they have similar usage and functionality. 

Different Types of Reflex Sights 

There are a few derivatives of the reflex sight that each have their own distinctive differences. Though they each achieve the same goal, their construction and the way they project light to form a reticle are different. Fortunately, with such a wide array of optic types, you’re bound to find one that suits your needs best. Below is a breakdown of some of the most common reflex sight variants. 

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Red Dot Sights  

Red dot sights are by far the most common sight variant you’ll see in the market today. Though simple in construction, premium brands build them with durable materials and tough cases to keep them resistant to obstruction, debris, shock, and water. While there are larger, full-size options, smaller micro red dots are common as well for sub-guns and PDW style rifles.  

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Commonly used on pistols, mini-reflex sights are a new type of sight that have surged in popularity. Compared to conventional dot sights, mini-reflex sights are much smaller, and as such, they can be used on handguns, or on rifles as an offset or backup sight. One of the big differences that separate these from red dot sights is the way they move when being adjusted for windage. On red dot sights, the entire optic assembly moves as a single combined one. For reflex sights, only the emitter moves when it’s being adjusted.  

A few notable examples of mini-reflex sights are our Classic Series Micro Reflex Sight, SLx RS-10, the Trijicon SRO and RMR, Holosun’s HS507C, and the Leupold Delta Point Pro. Our article on what to consider with a pistol red dot breaks down this optic type even further. 

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Holographic sights are the most complex of all the variants mentioned. While the other sights bounce light off one point to project a reticle on the glass, holographic sights bounce a light off multiple points to create a hologram reticle that’s projected between the optic’s objective lenses. Compared to standard red dot sights, there aren’t as many holographic optics available. Some of the most popular holographic sights are EOTech sights, and Vortex AMG UH-1 Gen II.  

If you’re looking to get a better idea of whether a standard red dot sight or holographic is better for you, our guide on holographic sights vs. red dots can help round out your knowledge on the two platforms.  

Which is best?  

There isn’t a ‘best’ option out of the list above. Each sight option has their own pros and cons, and ultimately it comes down to personal preference, as well as the firearm you’re using. Regardless of which one you end up going with, they can provide you with a lot of benefits. Also, our guide on red dot sights vs prism scopes will give you a better idea of how they differ from other optic variants. 

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Advantages of Using Reflex Sights/Red Dot Sights 

Compared to something like an LPVO or magnified prism scope, red dot sights can be beneficial to you in ways that other optics can’t. Better yet, these advantages can be seen across all forms of reflex sights, whether you opt for a conventional one or holographic.  

Core Benefits 

One such benefit is target acquisition speed. Red dots are sought after for how ‘quick’ they are. With large objective lenses and extremely forgiving eye relief, it’s easier to find a target through the optic. Compared to iron sights where you must line up both the front sight post and rear aperture, this is much faster, as all you do is line up the reticle on your target. With red dots, you can shoot with both eyes open, which enables you to see more of what’s downrange.  

Additionally, they can improve your accuracy. Like we said before, these sights use an LED to project a reticle pattern for you to use. These reticles are very crisp and stand out against anything you may be aiming at. This not only makes it faster to line up your reticle on target, but it makes it easier to aim in both bright and low-light environments.  

Finally, it goes without saying that red dots are some of the most versatile optics on the market. One of their major selling points is that they can be used with other optic accessories like magnifiers and night vision. Magnifiers do exactly as their name suggests; they magnify the reticle image on a red dot. For targets at distances further than 100 yards, being able to quickly switch a 3x magnified setting is incredibly helpful.  

If you shoot at night, you’re in luck. Most of the premium red dots available today have 2–3-night vision settings. They can easily be paired with NODs to see and shoot targets at night. Many hunters often use this combo for hunting feral hogs and other nocturnal invasive species.  

With all their benefits, red dot sights are tough optics that can withstand tough conditions. Still, there are some factors that can negatively affect their performance.  

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Potential Drawbacks 

With any kind of battery powered optic, the battery is often considered a point of failure, as without it, your optic doesn’t work. That said, battery drain is far less of an issue on modern red dot sights. The battery life on most red dots today far surpasses over 10,000 hours, with some lasting up to 50,000 hours. Even further, many of them feature automatic power controls, motion-based activation, and solar panels to take load off the battery when in use.  

Most holographic sights have long battery lives too, however when compared to standard red dots, they don’t last quite as long. Still, they have upwards of 1,000 hours of use time at normal settings, depending on the model.  

A further consideration is the optic’s usability in adverse conditions. Specifically affecting open emitter reflex sights, dirt and debris can be a more significant issue. Standard red dot and holographic sights are fully enclosed, so you don’t really have to worry about debris getting inside the optic. Open emitter sights can have their emitter blocked by debris if you’re using them in rough conditions. While it’s a problem that’s easily fixed, it’s still something to consider.  

Lastly, if you have astigmatism, red dot and reflex sights may not be the easiest optic to use. When using them, they can appear distorted or have the ‘starburst’ effect, making it difficult to fully utilize. While this can be corrected by using different sized reticles (3MOA or 6MOA) and adjusting the brightness to make the reticle appear crisper, it’s worth taking into consideration before purchasing. If astigmatism is hindering your ability to use red dot sights, you’ll likely benefit from using an LPVO or prism scope instead. Our SLx 1x MicroPrism™ and new GLx 1x MicroPrism™ have the same compact footprint as a red dot with benefit of having etched reticles. If you suffer from astigmatism, they’re definitely worth checking out. 

Reflex Sight Brands and Models 

We’ve been hinting at it throughout this article, but there are a lot of manufacturers producing their take on red dot sights. With the sheer variety available, it’s often difficult for beginners to determine which sights are worth getting.  


Primary Arms Optics 

One of our popular options is our line of red dot sights. Our Classic Series® 25mm Push Button Red Dot Sight is a great optic that satisfies all budgets. It’s built to withstand tough use in harsh conditions and has a battery life of upwards of 25,000 hours of run time. Likewise, our SLx® Advanced Rotary Knob Microdot is also incredibly durable but much smaller. This would be a solid option for smaller platforms like PCCs and PDWs, as it’s a lightweight and smaller alternative to other red dots on the market.  

We also produce mini-reflex sights for handguns. In our Classic Series®, we have the 21mm Micro Reflex Sight and the 24mm Mini Reflex Sight. Both have a 3 MOA dot and can be mounted to most compact and full-size handguns. In addition to them, our SLx RS-10 is another durable option that highlights the value of our SLx optics series. It’s constructed with durable materials and went through rigorous field testing to ensure its reliability in rough conditions.  

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EOTech is highly regarded as the creators of the most popular holographic optics available. Some of their models are the EXPS3-0, EXPS2-0, and the 512-0 Holographic Weapon Sights. Each of these models provide a great sight picture, have long lasting batteries, and work exceptionally well with magnifiers, with some models often being sold in a bundle with EOTech’s G43 or G45 which are 3x and 5x magnifier, respectively. Additionally, EOTech optics are known for their legendary night vision performance, so if you’re interested in shooting with night vision, EOTech is a suitable place to start when searching for an optic. 

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Holosun is one of the leading red dot sight manufacturers, and as such, they have an incredible number of optic offerings available. One of the most popular optics from Holosun is the AEMS. It’s a low profile, enclosed red dot sight that offers different reticle patterns, a long battery life, and solar power, depending on the variant you choose.  

Another solid optic choice is the HS515GM. It’s a 2 MOA red dot sight that’s built to be more robust and durable than some budget options on the market. It has multiple reticles, a battery life of over 50,000 hours, and has Holosun’s Shake Awake Motion Detection feature.  

Holosun also has a variety of mini-reflex and pistol red dot sights available, with some of their most popular options being the 507k, 507c, and HE509, which each have an option that uses our ACSS® Vulcan® Reticle.  

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Trijicon is another brand that needs no introduction. Though they’re most famous for the ACOG series of optics, they make some great red dots. The MRO for instance, has a large objective lens which provides a considerable field of view. Like the other optics in this list, it too boasts a long battery life and is exceptionally durable. There is an upgraded variant as well, the MRO HD, which uses a circle dot reticle and has upgraded lenses, battery life, and is optimized for magnifier use.  

In addition to their standard sized optics, Trijicon has the SRO and RMR mini-reflex sights. Both can be added to any handgun, so long as you use the proper mount. Also, they’re incredibly lightweight, coming in at only 1.2 ounces with the battery installed. Like the MRO, Trijicon also offers HD versions for the RMR.   

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Vortex Optics 

Though better known for their legendary variable power optics, Vortex Optics is a producer of the ever-popular SPARC red dot. It’s a micro red dot sight that is lightweight, has a simple and intuitive design, and is constructed from durable aluminum parts. It utilizes a 2 MOA dot reticle that is motion activated to conserve power.  

Vortex also offers mini-reflex sights, with their popular models including the Defender, Viper, and Venom sight. Each optic can be mounted to most pistol models, so long as you use the correct adapter plate.  

Vortex also produces a holographic sight, the AMG UH-1. It is a robustly built optic that blends holographic technology and Quantum Well Light Control to be efficient. While durable on its own, it’s coated in Vortex’s Armortek coating, which protects it from surface level damage it may receive when in use.  


Red dot sights are without a doubt some of the most versatile optics available. They’re capable of being used in some of the toughest environments, and compared to other optic variants, the versatility and agility they provide is highly sought after in today’s market.  

So, whether you’re looking for a standard red dot sight, a mini-reflex sight, or a holographic sight, you can rest assured knowing you’re getting a high quality, durable optic that’s perfect for every purpose. If you’re still on the fence about using a reflex sight, we recommend checking out the 5 things you should know before buying a red dot. It goes more in-depth on topics like mounting footprints and specific technologies that some red dot sights have.  

Once you’ve purchased a red dot, you should also check out what upgrades and accessories might be available to help you get the best possible performance. Check out our guide on the top red dot and scope accessories. It goes in depth on all the unique attachments and accessories that can enhance your red dot and your shooting experience.