The Ultimate Guide to Choosing a Red Dot Sight Magnifier

Red dot sights are optics that give the shooter an aim point in the form of an illuminated red (in some cases green) dot. They are very popular, especially among AR-15 style rifle owners because they’re easy to use and allow a quick acquisition of the target. They are generally designed to be used at close to moderate ranges and they usually don’t feature a built-in magnification. However, using a red dot sight in accordance with a magnifier can turn this simple device into a better distance system with performances comparable to a low powered scope. 

Magnifiers have become very popular too, and if you are among those who are considering purchasing one, you are in the right place: in this article, we aim to understand what RDS magnifiers are, how they work, who are they for, and what are the best on the market.

What Are RDS Magnifiers?

Red Dot Sights are perfect for fast target acquisition because, unlike traditional rifle scopes, they have no eye relief or exit pupil. The red or green dot you see through the sight is not projected like a laser, but bounced off a curved piece of glass and reflected back towards your eye. The limit of your sight picture is your field of view: if you are able to see the dot at all, you can use it to take a decently accurate shot. 

This doesn’t mean that red dot sights have no downsides or limits. Their main limit, indeed, is that they are perfect for close/moderate distances, but when shooting at longer distances their 1X magnification can affect accuracy and target identification. Also, red dot sights don’t increase your shooting range and this is where RDS magnifiers come into play.

RDS Magnifiers are devices that can be placed behind the red dot sight to increase the shooter’s range and improve their accuracy. Adding 3X-5X magnification to your sight, they would enhance sighting for a long-range and larger image.

How Do Magnifiers Work?

Simply speaking, magnifiers are attachments that are used with non-magnifying scopes to enhance range and accuracy.

Magnifiers are basically optical systems: convex lenses are used to produce a magnified image of an object. RDS Magnifiers usually use Doublet, Triplet or, Achromat Lens System: two lenses are used together to enhance magnification and eliminate distortion. 

There are two types of red dot magnifiers:

• Screw-in style magnifiers: an additional set of lenses is attached behind the red dot scope by directly threading into the scope body. Most Screw-in magnifiers provide 2X magnification.
• Magnifiers as standalone optics: they are placed behind the red dot scope in their own mounts. A fixed mount such a 30mm scope ring can be used, or you could opt for a flip-to-side configuration that allows you to engage or disengage the magnifier according to your needs.

Why Do You Need a Magnifier?

Red dot sight can offer great advantages when used at short ranges. In these cases, their lack of magnification, unlimited eye relief, and wide field of view allow the fast target acquisition. But at longer distances these features become their greatest weaknesses. 

Most RDS Magnifiers provide 3X magnification: this may not seem an impressive magnification, and it isn’t (good quality scopes provide 12X magnification), but they can make the difference in terms of shot accuracy at mid and long distances. When used with flip-to-side mounts, the shooter can also quickly engage or disengage their magnifier and using only the red dot sight when magnification is not needed.

On the other hand, RDS Magnifier can also have disadvantages: they have eye relief and eye boxes, so they can’t provide the same acquisition speed of red dot sights. You are also forced to choose just one possible magnification (2X, or 3X, or 5X…), because there is no possibility of smoothly transitioning your magnification from, say, 2X to 5X behind a red dot sight. As we mentioned before, you can at most choose whether to engage or disengage your magnifier, so transition from 1X to 3X (or 2X, or 5X…) magnification.

When to Use a Red Dot Magnifier

Whether or not to use an RDS Magnifier depends on the type of shooting you’re regularly involved in.

For shooters involved in short to medium range shooting (100 to 300 yards), a red dot sight with a flip-to-side magnifier would be ideal. For longer range shooting, instead, a high-powered scope would be preferable, since RDS Magnifiers would enlarge the red dot and affect aim accuracy.

Any magnifier reduces the shooter’s field of view which results in slower target acquisition. If your priority is the fastest target acquisition as possible, and accuracy at a longer distance in secondary, you may not want to use a magnifier for your red dot sight. 

Also, if you’d like to access more than one magnification setting using a single optic, then an RDS magnifier won’t suit you. 

In summary, you should use a red dot sight + magnifier when:

• Fast target acquisition is required;
• You won’t be shooting targets beyond 300 yards;
• You only desire two magnification option – 1X and 3X (rarely 5X or 6X);
• You’re shooting in conditions where eye position won’t be ideal.

How to Choose an RDS Magnifier

Now that you know what magnifiers are, how they work, and when you could make good use of them, let’s see what features and specifications you should check before purchasing your new RDS Magnifier.

Optical System Quality

Magnifiers are basically lens systems. Depending on how many lenses are used and how they’re attached together, the quality of the magnifier (and the image that you can see through it) may change.

The most common optical systems used on magnifiers are:

• Simple lens: a single positive lens is used. This system can only provide low power magnification (2X and 3X) and it tends to distort color on the outer fringes of the image.
• Doublet Lens: two lenses are used in conjunction with each other but not cemented together. This system can correct the color distortion produced by a simple lens and improve the quality of the image.
• Achromat: a positive simple lens is cemented to a negative simple lens. Most high-quality magnifiers use achromats for a high-quality image and high magnification power.
• Triplet: three lenses are cemented together to give no image distortion and a better-quality image. High-precision magnifiers use the triplet optical system.

Flatness Of Field and Color Distortion

Due to the curvature of the lens, the outer part of the image may appear out of focus, and the greater the magnification, the greater the problem. Lenses also produce a prism effect, giving the image false color fringes. Both problems can be overcome by using a more complex optical system (that uses more than one simple lens).

Magnification

Most units offer 3X magnification, but there are models that can offer magnification up to 6X. Although you may be tempted to go for the highest magnification power, always keep in mind that a higher magnification would reduce the field of view and your target acquisition’s speed. Also, for distance from 200 to 300 yards, 2X and 3X magnification already allow an accurate shot.

Mount Type

One of the advantages of using a magnifier in addition to your red dot sight is that you can easily and quickly switch from using it or disengage it. Flip-to-side (or slide-to-side) mounts would allow this freedom of choice. There are also fixed mounts available in the market (30 mm ring mounts) but they’re not recommended since they don’t allow to pick your target quickly at close range. 

Eye Relief

Unlike red dot sights, magnifiers have eye relief. Depending on the magnifier’s zoom capacity you’ll need several inches of eye relief to shot comfortably. Always check the product specification to learn how many inches of eye relief it requires.

Price

Magnifiers’ prices can go from less than $100 to more than $500. You certainly want to pick the best value for money: use a guide such as this one to learn about products’ features and prices before purchasing your new RDS magnifier.

Selecting the Right Magnifier for You

In order to select the best magnifier for your purposes, you should take the following elements into consideration:

• Number of elements: a single lens is satisfactory for low powers. If you need higher magnification power pick a magnifier that uses two or more lens elements.
• Field of View: the wider the field of view, the faster your target acquisition will be.
• Eye Relief: longer eye reliefs provide more comfortable viewing. Try to pick the RDS magnifier that features the longest eye relief.
• Coating: the best optical systems feature anti-reflection and anti-fog lens coating. 
• Mount: a flip-to-side mount is almost indispensable. Consider picking a magnifier with an included flip/slide-to-side mount.
• Water resistance: if you’re shooting sessions are particularly rough, be sure to pick a 100% waterproof device.

See below the best use for each RDS Magnifier on this list; it may help you figure out what’s the best choice for you.

What Makes a Good RDS Magnifier?

The perfect magnifier would be lightweight, have a large diameter and have a sturdy case. It should provide a wide viewing area and have an eye relief longer than 2 inches. It wouldn’t be necessary to have the highest magnification power – 3X magnification is enough for RDS magnifiers – It would be far more important to have a distortion-free magnification.

Setting up a Magnifier

1. Choose the right mount

Some magnifiers come with their mount included in the package. In some cases, you’ll have to purchase it separately. In both cases, you should keep in mind that a type of mount that allows you to engage or disengage your magnifier is always preferable. 

To learn how to properly mount your magnifier on your rifle consult the manual that comes with either the magnifier or the mount (if you’ve purchased it separately).

1. Zeroing

Magnifiers don’t need to be zeroed. Yet, the red dot sight that you use with it should be properly zeroed to ensure the best shooting experience.

1. Diopter adjustments

Some models offer the possibility of making diopter adjustment through a diopter adjustment ring: Aim your red dot sight + magnifier at a distant target and rotate the focus ring until you obtain a sharp image.

1. Shed weight from the front of your firearm

Using an RDS and a magnifier means having two optics and two mounts on your rifle and adding significant weight to it. The best way to mitigate this problem is to shed weight from the front of your firearm.

Does the Magnifier Go in Front of the sight?

You can’t mount the magnifier before the red dot. Since the magnifier is really a magnified scope, you need to worry about eye relief. If you mount it in the front, your eye will be beyond the eye relief range and will simply result in a dark image.

The right place where to mount your magnifier would be behind your red dot sight.

Best Magnifier Options on the Market

As magnifiers have become more and more popular, the market has responded with a wide variety of devices with different sizes, types and price ranges. 

Making the choice can be tricky, but this article may help you understand what features can better suit your needs and shooting habits. We also selected and reviewed some of the best magnifier options the market has to offer today. Read on to find out their features and how they can influence your shooting.

Vortex Optics VMX-3T 

The Vortex Optics VMX-3T is considered one of the best RDS magnifiers on the market today. This great value for money device is easy to use. It doesn’t require any special sight-in: just zero-in your red dot sight as normal and add the VMX-3T behind for additional 3x magnification.

Pros	Cons
Excellent lens system	Short eye relief
Flip mount	A bit heavy
100% waterproof and fog proof
Sturdy construction
Lifetime Warranty

Magnification

The VMX-3T features an excellent lens system with 3x magnification that makes the red dot very crisp and clear, allowing you to shoot mid/long-range shots with accuracy. Lenses are also provided with multiple anti-reflective coatings on every surface.

Mount

The flip-mount that it uses features a push-button design that allows you to switch between 3X magnified or unmagnified views in an instant. 

With the included flip mount and shim, there are two options for mounting the VMX-3T:

•  Flip Mount: The VMX-3T is placed at 37 mm from the base surface to center of the optics. When co-witness with AR-15 iron sights, this mount option puts the dot height at a center sight picture. For this height, do not install the included shim plate.
•  Flip Mount and Shim Plate: The magnifier is placed at 40 mm from the base surface to the center of the optics. When co-witnessed with a standard AR-15 iron sight, this mount option puts the dot height at a lower 1/3 sight picture.

After the VMX-3T is mounted in front of the red dot scope, the dot may seem off-centered while viewing through the VMX-3T. This will not affect the point-of-impact. If desired, the centering screws can be used to move the dot up/down or left/right until the dot is more centered.

Additional features

The O-ring sales prevent moisture, dust, and debris from getting inside the tube, making the device 100% waterproof and fog proof – this and the VMX 3-T’s sturdy construction (the magnifier’s casing is made out of high-grade anodized aluminum) make this RDS magnifier perfect to use in all environments.

The Vortex Optics VMX-3T comes with the company’s VIP Warranty, their unlimited lifetime warranty: it won’t cover loss, theft, or deliberate damage, but in any other case, the company will repair or replace any defected device with no costs for the customer.

Included in the package

• Vortex Optics VMX-3T magnifier
• Flip mount + Shim Plate

Customer Impressions

Although the EOTech G33 RDS Magnifier is a good quality device, some users complaints about its weight and, above all, its short eye relief.

EOTech G33 

The G33 Magnifier by EOTech is the first choice of America’s Elite Special Operation Forces. It’s the best choice for those who want to get more range out of their professional-grade red dot sights. The G33 magnifier is designed to be used behind an L-3 EOTech Holographic Weapon Sight (HWS). It can be mounted directly behind the HWS. 

Pros	Cons
Powerful optics with adjustable diopter	Small eye box
STS Mount	High Price
Waterproof and fogproof
Sturdy construction
Lifetime Warranty

Magnification

EOTech G33 uses powerful optics to enhance the magnification rate of your red dot sight by 3X, extending the range and accuracy of your firearm. Its extremely wide field of view allows the shooter to achieve improved magnification without compromising target acquisition.

Mount

The G33 features a Switch-to-Side (STS) Mount that allows the shooter to quickly engage and disengage the magnifier by flipping it on the side. The STS Mount also features an ambidextrous orientation to allow both left and right flip. To switch the magnifier to the side, simply push the optic to the right or left, depending on how it is mounted. To close the mount, push the magnifier back into its original position until a hard stop is achieved.

The magnifier doesn’t come preassembled to the mount. The user can configure the mount (choosing whether or not to use the included 7 mm) based on the specific model it will be mounted behind. 

Additional features

The EOTech G33 magnifier is waterproof up to 33 feet and its internal optics are 100% fog-proof. It features a tool-free azimuth adjustment and an adjustable diopter that allows the shooter to customize the focus to their particular vision. To adjust the diopter, the user should simply grasp the diopter with the thumb and forefinger and turn either clockwise or counterclockwise until a clear sight picture is achieved. This feature ensures a crisp, clear aiming dot for more precision and shot accuracy.

EOTech guarantees every product to be free from manufacturing defects in material and workmanship under normal use for a period of two years from the manufacturer’s date or customer’s proof of purchase.

Included in the package

• EOTech G33 Red Dot Sight Magnifier
• Switch to Side (STS) Mount
• 7mm Riser
• Screws
• Hard case

• EOTECH sticker

Customers Impressions

Those who have bought the G33 3X Magnifier by EOTech are pretty much satisfied with their purchasing. Some say that its price is too high for such a small device, but its overall quality is totally worth it.

Primary Arms 3X Long Eye Relief Red Dot Magnifier

With their PA3XLER-AD, Primary Arm provided their toughest and most advanced 3X magnifier. Compared to their previous generations of magnifiers, this one is smaller and weighs less and has a wider field of view.

Pros	Cons
Pairs with any red dot sight or holographic sight	No accessories included in the package
Low price
Lifetime Warranty

Magnification

The PA3XLER-AD features a 3X magnification with a generous eye relief – 3 inches – that enhances optical clarity and ensures fast target acquisition.

The 3X magnifier is also equipped with a fast-focus eyepiece. It must be set to match your eyes to optimizing the performance of the optics: you’ll just need to close your eyes for a few seconds, then open your eye and look through the optic at an object at least 100 yards away. Turn the eyepiece ring and repeat until the image appears sharp as soon as you glance through the scope. The eyepiece can be set before mounting the magnifier behind your red dot sight. 

Mount

The PA3XLER-AD fits any industry-standard 30mm magnifier mount, whether you prefer a fixed, flip-to-side or swing-away mount type. The Advanced 3X Long Eye Relief Red Dot Magnifier also pairs with any red dot sight or holographic sight.

Additional Features

The integrated diopter provides a fast focus ability to keep the image clear. Azimuth and elevation adjustments keep the dot centered in your field of view. A rubber armor sleeve protects the body of the optic from harsh impacts.

The PA3XLER-AD magnifier is covered by the Primary Arms Lifetime Warranty. If a defect due to materials or workmanship, or even normal wear and tear, has caused your product to malfunction, Primary Arms will either repair or replace your product. 

Included in the Package

• Primary Arms 3X Long Eye Relief Advanced Red Dot Magnifier
• Lens Covers

Customers Impressions

Most users are satisfied with their PA3XLER-AD. The only complaint that we could read about it regards its mount: some users had to buy a good quality mount separately in order to attach the magnifier to their firearm. But, keeping in mind its low price (less than $100), this PA3XLER-AD is a great value for money.

Leapers UTG 3X Magnifier

The UTG 3X Magnifier by Leapers features a wide field of view and a flip-to-side mechanism that allows the shooter to quickly transition between 1X and 3X magnification.

Pros	Cons
Excellent optics	Short eye relief
Low price
Flip-to-side mount
Lifetime Warranty

Magnification

The UTG 3X Magnifier features a 3X magnification. 

A multi-layer lens coating offers optimum light transmission and optimizes optical performance to allow utilization with all light conditions, enhancing resolution and clarity. The UTG 3X magnifiers also feature a built-in corrective lens system to make the shooter see a sharp and crisp red dot.

Mount

This magnifier features a flip-to-side mechanism to allow a quick transition between 1X and 3X images. The switch is easy and quick: pull the magnifier back towards you and rotate the magnifier clockwise till the hinge component is locked to exclude the magnifier from your view, and execute the opposite procedure when you need to use the magnifier again.

Additional Features

The Leapers UTG 3X Magnifier body is completely sealed and nitrogen filled to eliminate the risk of water ingress or fogging, making the device 100% waterproof and fog proof. The construction is solid and sturdy for enhanced durability.

Aiming your red dot sight + magnifier at a distant target and rotating the focus ring, you can adjust the focus and diopter to obtain the sharpest image.

The lifetime warranty that comes with the Leapers UTG 3X Magnifier applies based on some condition:

• The magnifier isn’t a first-hand purchase (Evidence of purchase will be required)
• The magnifier isn’t disassemble
• The magnifier has not been used unproperly or willingly damaged 

Included in the package

• Leapers UTG 3x Red Dot Magnifier with Flip-to-side QD Mount

Customers Impressions

The main flaw that users noticed about this device is its short eye relief. All of its other features, included its price, have been appreciated by customers.

Sightmark 5x Tactical Magnifier Pro

SightMark constructed the 5X Tactical Magnifier Pro from durable, lightweight aluminum with IPX6 protection that makes the magnifier 100% waterproof for use in any weather and condition. For extended durability, the optics is also protected by a rubber armor housing. Compared to the previous generations, the sight has been redesigned to increase eye relief to provide a more comfortable shooting experience.

Pros	Cons
Durability	Blurry Image
Long eye relief
Wide field of view
External windage and elevation adjustments

Magnification

The Sightmark 5X Tactical Magnifier Pro features a 5X magnification. Designed to assist in quick target acquisition up to 350 yards and accurate target shooting at 150 yards, the 5x Tactical Magnifier also features extended eye relief for comfort, a wide field-of-view and high-quality multi-coated optics for improved visibility and clarity.

Mount

Sightmark Tactical Magnifiers are designed for use in conjunction with holographic, collimated reflex, and other compatible weapon sights. When mounting, be sure the magnifier is placed behind the sight. Tactical Magnifier Pro features a slide-to-side mount that allows the shooter to choose whether to engage or disengage the magnifier. The magnifier attaches to the firearm through a waver mount (that comes with the magnifier). A lever on the left side would activate the slide mechanism.

Additional features

Inspired by military and law enforcement applications, the Tactical Magnifier Pro is designed to ensure durability in all environments: it’s lightweight, 100% waterproof, and it’s provided with a  shatter-proof frame.

Sightmark will replace any defected item. However, their warranty has some limits, so you should carefully read the Warranty Section on their Manual for detailed information.

Included in the package

• Magnifier 
• Slide to side mount

Customers Impressions

Even though most users are happy with their Sightmark Tactical 5X Magnifier Pro, some reported a feature that makes the magnifier unusable: in some cases, the lens system seems to provide a blurry image.

Aimpoint 3XMag-1 Magnifier

The Aimpoint 3XMag-1 features the perfect between lightweight and ruggedness thanks to its hard-anodized aluminum case and protective rubber cover that also provides an ergonomic grip for solo use (the 3XMag-1 can also be used as a handheld 3X monocular).

Pros	Cons
Durable	No mount included
Lightweight and sturdy
Excellent Optics
Waterproof
Can be used as handheld monocular

Magnification

The 3X Mag-1 by Aimpoint features a 3X magnification. The lenses are multi-coated and ensure a daylight transmission of 75%. Two controllers are available that allow the centering of the red dot. They have no influence on the zeroing of the sight but instead center the optical reference point within the device. This allows the interplay between the red dot and the magnifying module to be utilized more effectively.

The 3XMag does not need to be zeroed, but, the red dot sight used together with it must be zeroed so that the red dot of the sight creates the correct point of impact.

Mount

Aimpoint recommends the use of the Aimpoint TwistMount, but you could also use a mount of your choice (the device features a 30 mm diameter, so be sure to use a compatible mount). In any case, the 3X Mag-1 should be mounted with the flat metal surface facing downwards.

Additional Features

Waterproof to a depth of 25 meters, this optic magnifier can hold up in rainy scenarios. For further customization to your eyesight, this device features a variable (-3 to +3) dioptric setting that allows you to adjust it to your eye precisely.

Included in the package

• Aimpoint 3X Mag-1 Magnifier

Costumers Impressions

The Aimpoint 3X Mag-1 has excellent reviews. Although the magnifier doesn’t come with its own mount, nobody seems to complain about this. 100% of users seem to be satisfied.

Sig Sauer Juliet4

The Sig Sauer Juliet 4 is very versatile: it can be used as a standalone or in conjunction with a red dot sight.

Pros	Cons
Excellent optics	Expensive
4X Magnification
Flip-to-side mount
Lifetime Warranty

Magnification

Juliet 4 features a 4X magnification. The magnifier needs to be adjusted to match your red dot sight. To do this, use the windage and elevation adjustment dials on the top and right side of the magnifier to adjust the magnifier so that the red dot is located in the center of the field of view. Juliet 4 also has an adjustable diopter. To make the adjustments rotate the diopter adjustment ring until the aiming feature is crisp and clear.

Mount

Juliet 4 comes with two separate mounting plates that allow the user to mount the magnifier behind optics ranging from 1.41” to 1.63”. If you need to raise the height of the Juliet you will need to remove your magnifier from the base and re-attach it with the correct riser plate and its corresponding length screws. Once you have selected the correct height, mount the magnifier behind your red dot sight. The mount is provided with a quick-release lever that can be adjusted (through the adjustment screw) so that the magnifier can be installed and removed without adjustment (avoid over-tightening the screw or you will not be able to operate the quick-release lever).

Additional features

The Juliet 4 Magnifier is waterproof up to 20 M and it can maintain its waterproof feature for 1 hour.

It comes with SIG SAUER Electro-Optics Infinite Guarantee, a lifetime guarantee. They will repair or replace your SIG SAUER product in the event it becomes damaged or defective, at no charge to you. If they cannot repair your product, they’ll replace it with a product in perfect working order of equal or better physical condition. It doesn’t matter how it happened, or where you purchased it.

Included in the package

• Juliet 4X Magnifier
• Juliet Flip Away Mount
• Screws 
• 1.53” Spacer Plate
• 1.63” Spacer Plate
• Hex Tool
• 2 Thread-In Lens Covers
• Flip Back

Customers Impressions

The Sig Sauer Juliet has mostly positive reviews. Only its price is a bit high, but when the only complaint about a product is about its price, it usually means that the device is well made, works well and it’s worth the price.

Good Budget Option Magnifiers

There are a couple of very affordable models in our list of the best RDS magnifier. We thought of comparing them with a couple of other cheap magnifiers that were not included in the above list.

Magnifiers Compatible with EOTech

In our list of the best red dot sight magnifiers on the market, we included the EOTech G33 which is, of course, compatible with EOTech sights, considered among the most popular and top-quality holographic sights on the market. The G33 can be expensive for some users. That’s why we also wanted to include a couple of other EOTech-compatible models that come to a lower price. They are the Vortex-3T Magnifier and the UTG 3X Magnifier.

In particular, the UTG 3X is super affordable: it comes at $69, while the EOTech G33 costs $569. The field of view it offers is not as wide as the EOTech G33’s, and its eye box is also tighter, but it’s still a valid option: it’s very sturdy and features great multi-coated lenses that can give a crisp image of the field and a clear red dot. 

The Vortex-3T stays in the middle, with a price of $233. This is probably the best value for money: it features an excellent lens system and sturdy construction. It also features the same eye relief as the EOTech G33 and a wider field of view.

Conclusion

Unless you’re always shooting in a range of 100 yards, attaching a magnifier to your red dot sight can be extremely useful. Your shot accuracy and target identification would drastically improve. With this guide, we just gave you every information you need to make the best choice for your needs, shooting habits, and budget.