Modifying the angle of view over time (known as zooming), is a frequently used cinematic technique, often combined with camera movement to produce a "dolly zoom" effect, made famous by the film Vertigo. Using a wide angle of view can exaggerate the camera's perceived speed, and is a common technique in tracking shots, phantom rides, and racing video games. See also Field of view in video games.

To project a sharp image of distant objects, S 2 {\displaystyle S_{2}} needs to be equal to the focal length, F {\displaystyle F} , which is attained by setting the lens for infinity focus. Then the angle of view is given by:

Green dots, though…oh my. I’m a HUGE fan of green dots. But they can be a little strange with magnifiers. First off, every single one I’ve tried tear-dropped the dot a little. I have no idea why.

Field of view calculationcalculator

It’s very hard to take good pictures using an optical camera looking through an optical device that is looking through an optical device that is pointed downrange at something.

The purpose of this test is to measure the horizontal and vertical FOV of a lens and sensor used in an imaging system, when the lens focal length or sensor size is not known (that is, when the calculation above is not immediately applicable). Although this is one typical method that the optics industry uses to measure the FOV, there exist many other possible methods.

This magnifier offers the same eye relief as the Juliet6 at 2.5 inches, but a smaller field of view at only 19.1 feet at 100 yards.

As noted above, a camera's angle level of view depends not only on the lens, but also on the sensor used. Digital sensors are usually smaller than 35 mm film, causing the lens to usually behave as a longer focal length lens would behave, and have a narrower angle of view than with 35 mm film, by a constant factor for each sensor (called the crop factor). In everyday digital cameras, the crop factor can range from around 1 (professional digital SLRs), to 1.6 (mid-market SLRs), to around 3 to 6 for compact cameras. So a standard 50 mm lens for 35 mm photography acts like a 50 mm standard "film" lens even on a professional digital SLR, but would act closer to a 75 mm (1.5×50 mm Nikon) or 80 mm lens (1.6×50mm Canon) on many mid-market DSLRs, and the 40-degree angle of view of a standard 50 mm lens on a film camera is equivalent to a 28–35 mm lens on many digital SLRs.

But if you’re on a budget, we tested out a ton of magnifiers under $200 (and one that is over $500…) so you can get a real look at what you’re paying for.

In photography, angle of view (AOV)[1] describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view.

The total field of view is then approximately: F O V = α D d {\displaystyle \mathrm {FOV} =\alpha {\frac {D}{d}}} or more precisely, if the imaging system is rectilinear: F O V = 2 arctan ⁡ L D 2 f c d {\displaystyle \mathrm {FOV} =2\arctan {\frac {LD}{2f_{c}d}}}

I would argue that if you’re looking at spending this money on a 6x, you might be better off with an LPVO, but you do you.

If the subject image size remains the same, then at any given aperture all lenses, wide angle and long lenses, will give the same depth of field.[15]

Concerning the UTG you didn't explain why you think the mount suck or what the body design issues were. Out of the box the mount works like one of the others but you don't mention why it sucks more, AND it actually flips the correct way for a right handed shooter that uses both eyes as one should with a red dot sight.

I've never used a 3x magnifier before, but I'm thinking about putting one behind my 512. Question to those who have used magnifiers: when engaged, are you closing one eye and lining up behind this like a scope, or are you still keeping both eyes open like on a HWS or red dot?

Though it might not seem like it, the lack of a mount is a blessing in disguise. No mount means you save some money on something you don’t want and can, instead, grab the one you do want.

Now α / 2 {\displaystyle \alpha /2} is the angle between the optical axis of the lens and the ray joining its optical center to the edge of the film. Here α {\displaystyle \alpha } is defined to be the angle-of-view, since it is the angle enclosing the largest object whose image can fit on the film. We want to find the relationship between:

Camerafield of viewsimulator

The writer needs to have a conversation with the website designer. The writer says that the Vortex 3x, “doesn’t win any prizes”. And then the web designer slapped the “Best 3X Magnifier” badge on the Vortex picture.

Because different lenses generally require a different camera–subject distance to preserve the size of a subject, changing the angle of view can indirectly distort perspective, changing the apparent relative size of the subject and foreground.

I have the Holosun 3x magnifier that I recently bought to pair with my Sig Romeo 7 (not the 7s) red dot. While I like the magnifier, I have a problem with the alignment. Out of e box, the Holosun sits too low to align with the Romeo 7. No problem, I'll just add the spacer that came with the magnifier, and all will be right, right? Um, no. With the spacer installed, the Holosun now sits higher than the red dot! Ugh! I searched online to see if Holosun has a thinner spacer available, but I couldn't find any such thing. Anyone knows of a solution for this problem, short of buying a new red dot? I thought of having a buddy make a custom spacer with his 3D printer, but don't know if plastic would be reliable for that. Thanks for any advice!

Field of viewhuman eye

Using basic trigonometry, we find: tan ⁡ ( α / 2 ) = d / 2 S 2 . {\displaystyle \tan(\alpha /2)={\frac {d/2}{S_{2}}}.} which we can solve for α, giving: α = 2 arctan ⁡ d 2 S 2 {\displaystyle \alpha =2\arctan {\frac {d}{2S_{2}}}}

Overall, it’s a fantastic budget option (pretty hard to upgrade out of). If you can, spend some money on the mount and get a good one.

Another result of using a wide angle lens is a greater apparent perspective distortion when the camera is not aligned perpendicularly to the subject: parallel lines converge at the same rate as with a normal lens, but converge more due to the wider total field. For example, buildings appear to be falling backwards much more severely when the camera is pointed upward from ground level than they would if photographed with a normal lens at the same distance from the subject, because more of the subject building is visible in the wide-angle shot.

I have the Vortex 3x Micro and you can make it flip to the left or the right. You just take the magnifier off the mount and flip it.

As a result, this model sports improved glass clarity, better eye relief, and a thinner bezel than the original model we tested.

To add: The sightmark is 10.6 ounces which is a little more than some of the magnifiers in this article. I found the advertised eye relief spec to be accurate for me. The glass seemed surprisingly nice, and crystal clear, considering the price. The eye box was not as good as the Sig but still wasn't bad and was better than the PA magnifiers I've tried.

Magnifiers magnify the dot and the target. If your 2 MOA dot is covering their nipple at 100 yards, it will cover their nipple and no more at 400 yards.

This table shows the diagonal, horizontal, and vertical angles of view, in degrees, for lenses producing rectilinear images, when used with 36 mm × 24 mm format (that is, 135 film or full-frame 35 mm digital using width 36 mm, height 24 mm, and diagonal 43.3 mm for d in the formula above).[16] Digital compact cameras sometimes state the focal lengths of their lenses in 35 mm equivalents, which can be used in this table.

Since this article was published, PA has come out with the "Primary Arms Advanced 3X Long Eye Relief Magnifier"....it's better than the vortex (glass, eye relief, FOV, and weight), and is cheaper at $169. I think it's even better than the original Aimpoint 3X. I still think the Eotech flip-mount is the best one made (easier than any of the others to use).

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The sensed image, which includes the target, is displayed on a monitor, where it can be measured. Dimensions of the full image display and of the portion of the image that is the target are determined by inspection (measurements are typically in pixels, but can just as well be inches or cm).

Help me out, David. When you talk about IP ratings, are you referring to the "ingress protection" code as defined by the International Electrotechnical Commission (IEC) under international standard IEC 60529, which classifies and provides a guideline for the degree of protection provided by mechanical casings and electrical enclosures against intrusion, dust, accidental contact, and water? It's been so long since I shopped optics I was not aware they came with an IP code.

The eye relief is average, but the eye box is large. Even with a camera, the Micro was almost always just BAM — right there and easy to use.

Perhaps a stupid question, but.... if I have a SIG Romeo5 red dot and pair it with a non-SIG magnifier, will I find that the focal center of the two optics will not align and I end up with a "football shaped" view through the optics pair? I there a way to adjust height such that the location of the red-dot aligns with the focal center of the magnifier? Are the heights standardized across manufacturers?

The table below shows the horizontal, vertical and diagonal angles of view, in degrees, when used with 22.2 mm × 14.8 mm format (that is Canon's DSLR APS-C frame size) and a diagonal of 26.7 mm.

Yesterday at the range I saw a guy using a SightMark T-3 Magnifier with their quick disconnect (LQD) Flip to Side Mount. Yes, I know, people go "Sightmark Ugggghhh no way!" I asked him about it, he had it mounted behind a Sig Romeo 5 red dot. He sort of raved about it a bit and said "here, give it a try." and took it off his rifle and handed it to me. I snapped it in place on my rifle behind the red dot I was using (also a Sig Romeo 5), adjusted the focus a bit, and was impressed some for such a budget level price optic. Eye box matched that of my Sig Juliet 3 Micro, almost, a little different but not bad at all. Clarity was good. It was a lot better than any of the PA magnifiers I've tried, and view was on par with the Vortex VMX-3T. So its $99.00'ish if someone wants another decent budget option.

Holosun seems like it could be great, BUT, they must use a bottle of threadlock on each bolt so if you want to add riser or flip the mount 180, you’ll strip and ruin the bolt. Pretty piss poor

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Field of viewcalculator

To help you get a better idea of how the magnifiers we tested stacked up against one another, we took some pictures. Feel free to zoom in or open in a new tab, as the source image is decently large.

A camera's angle of view depends not only on the lens, but also on the sensor. Digital sensors are usually smaller than 35 mm film, and this causes the lens to have a narrower angle of view than with 35 mm film, by a constant factor for each sensor (called the crop factor). In everyday digital cameras, the crop factor can range from around 1 (professional digital SLRs), to 1.6 (consumer SLR), to 2 (Micro Four Thirds ILC) to 6 (most compact cameras). So a standard 50 mm lens for 35 mm photography acts like a 50 mm standard "film" lens on a professional digital SLR, but would act closer to an 80 mm lens (1.6×50mm) on many mid-market DSLRs, and the 40-degree angle of view of a standard 50 mm lens on a film camera is equivalent to an 80 mm lens on many digital SLRs.

Sometimes you need to think backwards. Things further away appear smaller. What they have said is not only does the object appear smaller but the red dot does as well.

Field of view calculationonline

How could you leave out the $170 Samson 3X magnifier which is a better magnifier than even the $450 Aimpoint 3X? Also, Holosun has a $200 3X magnifier out although reviews of it are nonexistent.

Because this is a trigonometric function, the angle of view does not vary quite linearly with the reciprocal of the focal length. However, except for wide-angle lenses, it is reasonable to approximate α ≈ d f {\displaystyle \alpha \approx {\frac {d}{f}}} radians or 180 d π f {\displaystyle {\frac {180d}{\pi f}}} degrees.

On top of it all, the PA 3x proves to be a good magnifier. It brings a great field of view and feels pretty light at 7.9 ounces. The only downside is no IPX rating. That said, it’s been durable in my use.

Vortex Micro 3x all day. Compact design, no push button to flip (buttons should disqualify magnifiers from "best" lists) great optic and fantastic warranty. Not on the list because?

Consider a 35 mm camera with a lens having a focal length of F = 50 mm. The dimensions of the 35 mm image format are 24 mm (vertically) × 36 mm (horizontal), giving a diagonal of about 43.3 mm.

This testing was the result of about two months of hard use and a lot of rounds downrange. We’ve used each of these magnifiers much longer and more than that, but the concentrated effort for this review was within that scope.

However, this is a very lightweight magnifier for its size, coming in at just 7.2 ounces (less than half the Juliet6). With a solid mount included and a reasonable price tag of $299, the GLx 6x makes for an appealing option.

Many of the aftermarket options that fit the Aimpoint will also fit the Primary Arms options. So you get a lot of options depending on what you want to spend.

d {\displaystyle d} represents the size of the film (or sensor) in the direction measured (see below: sensor effects). For example, for 35 mm film which is 36 mm wide and 24 mm high, d = 36 m m {\displaystyle d=36\,\mathrm {mm} } would be used to obtain the horizontal angle of view and d = 24 m m {\displaystyle d=24\,\mathrm {mm} } for the vertical angle.

True it is pretty darn good, but their mount flips the wrong way for a right handed both eye open shooter. You can flip it around but then it gets a little awkward.

UV/visible light from an integrating sphere (and/or other source such as a black body) is focused onto a square test target at the focal plane of a collimator (the mirrors in the diagram), such that a virtual image of the test target will be seen infinitely far away by the camera under test. The camera under test senses a real image of the virtual image of the target, and the sensed image is displayed on a monitor.[9]

I want to get the Vortex but flipping to the left just seems backward -- both for vision impairment and resting position - sticking into your abdomen. You can switch it but then the release is front right instead of left back. I'm newer so I might be missing something.

Field of viewcamera

Learning how to shoot at a young age in the Boy Scouts, David now spends most of his time working on or with firearms. Be it shooting, upgrading, building, tinkering, or writing about them - sharing his passion and knowledge of firearms with others is an everyday occurrence.

What is an IP rating? IP (or "Ingress Protection") ratings are defined in international standard EN 60529 (British BS EN 60529:1992, European IEC 60509:1989). They are used to define levels of sealing effectiveness of electrical enclosures against intrusion from foreign bodies (tools, dirt etc) and moisture.

For a given camera–subject distance, longer lenses magnify the subject more. For a given subject magnification (and thus different camera–subject distances), longer lenses appear to compress distance; wider lenses appear to expand the distance between objects.

From the definition of magnification, m = S 2 / S 1 {\displaystyle m=S_{2}/S_{1}} , we can substitute S 1 {\displaystyle S_{1}} and with some algebra find: S 2 = F ⋅ ( 1 + m ) {\displaystyle S_{2}=F\cdot (1+m)}

It is important to distinguish the angle of view from the angle of coverage, which describes the angle range that a lens can image. Typically the image circle produced by a lens is large enough to cover the film or sensor completely, possibly including some vignetting toward the edge. If the angle of coverage of the lens does not fill the sensor, the image circle will be visible, typically with strong vignetting toward the edge, and the effective angle of view will be limited to the angle of coverage.

For a 3x magnifier, the Sig Juliet 3 Micro is probably the best and best bang for the buck and the best way to go for most budget people. I love mine, but I got mine for free as a present. I've tried some of the others: The PA magnifiers I absolutely hate, they are still using that basic Chinese design that I-Tac imports from China and its a piece of junk for long term reliability and durability plus the eye box is not good and not forgiving. The Holosun isn't bad at all, its nice, I liked the mount and the clarity. The Vortex, meh .... nothing to crow about, its ok and overall average but still a solid choice if you are inclined towards Vortex. But out of all of them I prefer the Sig Juliet 3 Micro. I wish it had a mount like the Holosun though but the push button doesn't really bother me and the color and clarity for me was on par with the Holosun (although the Holosun did seem to have a very slight more depth of color look for me). The Juliet 3 eye box was a little more comfortable for me than the Holosun eyebox.

Note that the angle of view varies slightly when the focus is not at infinity (See breathing (lens)), given by S 2 = S 1 f S 1 − f {\displaystyle S_{2}={\frac {S_{1}f}{S_{1}-f}}} rearranging the lens equation.

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Defining f = S 2 {\displaystyle f=S_{2}} as the "effective focal length", we get the formula presented above: α = 2 arctan ⁡ d 2 f {\displaystyle \alpha =2\arctan {\frac {d}{2f}}} where f = F ⋅ ( 1 + m ) {\displaystyle f=F\cdot (1+m)} .

Another great data and information filled review. Your perspective is appreciated. Any chance we will see an update review to include some of the competitors, up and down the price scale?

Holosun basically did everything right with their magnifier. After using all of these a lot, I have to say that this is my go-to.

When it comes down to it, though, there aren’t a ton of differences between the Primary Arms, Holosun, Vortex, and Sig magnifiers.

But…it’s IPX8-rated and offers a QD mount. The unit feels great and is easy to flip over; a really nice magnifier in general.

It features a QD mount and an IP67 rating — the only option we reviewed that was BOTH dust and water-rated. It also boasts a 37-foot field of view at 100 yards and weighs 9.5 ounces.

Consider a rectilinear lens in a camera used to photograph an object at a distance S 1 {\displaystyle S_{1}} , and forming an image that just barely fits in the dimension, d {\displaystyle d} , of the frame (the film or image sensor). Treat the lens as if it were a pinhole at distance S 2 {\displaystyle S_{2}} from the image plane (technically, the center of perspective of a rectilinear lens is at the center of its entrance pupil):[6]

While we tested Primary Arms’ original 6x magnifier, it has since been discontinued and replaced by their GLx 6x magnifier. While we haven’t got our hands on this one for testing yet, we have enjoyed other PA optics from the same lineup.

I do not follow your talk about magnifying the red dot. First you say, "red dots DO NOT increase in size with a magnifier". Then you say, "Magnifiers magnify the dot and the target". This sounds contradictory. Perhaps you meant they don't increase is size relative to the target with magnification. Then you say, "If your 2 MOA dot is covering their nipple at 100 yards, it will cover their nipple and no more at 400-yards. " That doesn't sound right either. If you stand far enough away the dot will cover your whole body. Then you say, "The claim is that a 2 MOA dot will cover 2 inches at 100 yards, 4 inches at 200 yards, etc. But this is totally and completely false." I don't understand that. A 2 MOA is 2" at 100 yards and 4" at 200 yards. That's just what MOA is. Perhaps you meant if it covers a nipple at 1x it will cover no more than a nipple at 4x magnification??

(In photography m {\displaystyle m} is usually defined to be positive, despite the inverted image.) For example, with a magnification ratio of 1:2, we find f = 1.5 ⋅ F {\displaystyle f=1.5\cdot F} and thus the angle of view is reduced by 33% compared to focusing on a distant object with the same lens.

The collimator's distant virtual image of the target subtends a certain angle, referred to as the angular extent of the target, that depends on the collimator focal length and the target size. Assuming the sensed image includes the whole target, the angle seen by the camera, its FOV, is this angular extent of the target times the ratio of full image size to target image size.[10]

Love my Romeo MSR and Juliet 3x magnifyer. Works very well on my Springfield Saint! Sighted the pair using my Pew Pew Tactical red dot target.

Also worth mentioning, red dots DO NOT increase in size with a magnifier. This is a piece of lore that just won’t die. The claim is that a 2 MOA dot will cover 2 inches at 100 yards, 4 inches at 200 yards, etc.

Wyatt Sloan was raised on hunting and target shooting from a young age. What started as a few guns turned into a bunch — almost 200 firearms. Sprinkle a journalism degree on top of a couple of decades of shooting experience, and he found himself at the doorstep of Pew Pew Tactical, where he enjoys sharing his hobby with fellow and aspiring gun owners. Collectively, he has 20 years of outdoor rifle, pistol, shotgun, and bow hunting experience and previously competed in USPSA. Wyatt also had 10 years of home-based FFL firearms sales and transfers. He now serves as Junior Editor and Fact Checker for Pew Pew Tactical.

With that out of the way, let’s talk about red dots versus holographic sights. Really, there’s not much difference between them. Technically, holographic sights are a little finer since their emitter is smaller…kind of.

Field of viewmicroscope formula

A second effect which comes into play in macro photography is lens asymmetry (an asymmetric lens is a lens where the aperture appears to have different dimensions when viewed from the front and from the back). The lens asymmetry causes an offset between the nodal plane and pupil positions. The effect can be quantified using the ratio (P) between apparent exit pupil diameter and entrance pupil diameter. The full formula for angle of view now becomes:[7] α = 2 arctan ⁡ d 2 F ⋅ ( 1 + m / P ) {\displaystyle \alpha =2\arctan {\frac {d}{2F\cdot (1+m/P)}}}

There is a lot to unpack in this review, but I hope we’ve given you the tools you’ll need to pick the magnifier right for you.

For me, the Sig Juliet 3 ( non micro ) with the flip to side quick release mount hits the sweet spot. I agree hat 3x is probably perfect for a flip to side magnifier, and I got mine at $269.00 delivered, so it is not too far over the limit price wise. I use it behind my Sig Romeo 5XDR red dots, though it also works behind the Primary Arms SLx ACSS CQB 25mm Microdot very well. I love the fact that many of the newer sights and magnifiers include the adjustment plates for 1/3 and absolute co-witness, which really helps to get the magnifier and sight aligned perfectly.

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Zoom lenses are a special case wherein the focal length, and hence angle of view, of the lens can be altered mechanically without removing the lens from the camera.

For macro photography, we cannot neglect the difference between S 2 {\displaystyle S_{2}} and F {\displaystyle F} . From the thin lens formula, 1 F = 1 S 1 + 1 S 2 . {\displaystyle {\frac {1}{F}}={\frac {1}{S_{1}}}+{\frac {1}{S_{2}}}.}

For a lens projecting a rectilinear image (focused at infinity, see derivation), the angle of view (α) can be calculated from the chosen dimension (d), and effective focal length (f) as follows:[4] α = 2 arctan ⁡ d 2 f {\displaystyle \alpha =2\arctan {\frac {d}{2f}}}

The Juliet6 6x magnifier is way outside the price range of the other options listed, but it was included in all of the tests because Sig sent it along with the Juliet3.

Don’t get me wrong, the Vortex is still a great unit, but it didn’t stand out. Glass clarity was on par, price is average, weight is a little heavy, eye relief is average, field of view is good but only by a foot, and there was no IP rating.

Though the field of view isn’t amazing, it isn’t bad either at 35 feet at 100 yards. I’m a huge fan of Sig IP testing their magnifiers, and the micro clocks an IPX7 rating.

If you don’t already have a sight to pair your magnifier with, you should view them as a pair. While, on their own, they are good, it’s really together that matters.

Holosun has really fantastic glass and lines up perfectly (not surprising) with the Holosun 510c. The flip is pretty stiff at first. Still breaking that in.

I think the part I like best about the Vortex is that the Vortex warranty always has my back. Outside of that, it felt a little dated.

Re: red vs green dot. It is very common for guys to be color blind in the red. I know I am slightly colorblind in the red.

Vortex made a huge design flaw in choosing the Eotech mount pattern instead of just making it a 30mm tube. The only quick detach mounts available for the Eotech pattern are from Larue Tactical and Eotech themselves. Both are very expensive and from what I read the Larue doesn't line up well. With the Primary Arms option you have a wider selection of quick detach mounts, including ADM's excellent swing off mount. Also, the newest Primary Arms magnifier increases the field of view, eye relief, and has a much smaller footprint. For me, the ability to remove the magnifier quickly and run just the red dot optic is extremely important for this setup. Otherwise, might as well go with a 1-6 optic if you are willing to deal with the added weight and footprint 100% of the time.

The target's angular extent is: α = 2 arctan ⁡ L 2 f c {\displaystyle \alpha =2\arctan {\frac {L}{2f_{c}}}} where L {\displaystyle L} is the dimension of the target and f c {\displaystyle f_{c}} is the focal length of collimator.

The effective focal length is nearly equal to the stated focal length of the lens (F), except in macro photography where the lens-to-object distance is comparable to the focal length. In this case, the magnification factor (m) must be taken into account: f = F ⋅ ( 1 + m ) {\displaystyle f=F\cdot (1+m)}

At only $100, Primary Arms comes in cheap. But it doesn’t come with a mount, so I used the Primary Arms Flip to Side priced at $50. The total package is still cheap, but this mount is…okay.

Overall, each magnifier is clearer and easier to see in real life than in the pictures. But the pictures give you a good idea of side-by-side expectations.

FOV to focal length calculator

For lenses projecting rectilinear (non-spatially-distorted) images of distant objects, the effective focal length and the image format dimensions completely define the angle of view. Calculations for lenses producing non-rectilinear images are much more complex and in the end not very useful in most practical applications. (In the case of a lens with distortion, e.g., a fisheye lens, a longer lens with distortion can have a wider angle of view than a shorter lens with low distortion)[3] Angle of view may be measured horizontally (from the left to right edge of the frame), vertically (from the top to bottom of the frame), or diagonally (from one corner of the frame to its opposite corner).

We pride ourselves on hands-on testing and real-world experience with all products we recommend. Further, we believe in objectivity and approaching all articles without bias – our few advertisers never influence our reviews or recommendations. We believe in giving our readers a comprehensive understanding of how and why a product is great – or isn’t. And if it’s good enough for us to use ourselves and recommend to loved ones.

In the optical instrumentation industry the term field of view (FOV) is most often used, though the measurements are still expressed as angles.[8] Optical tests are commonly used for measuring the FOV of UV, visible, and infrared (wavelengths about 0.1–20 μm in the electromagnetic spectrum) sensors and cameras.

Looking for tried and true combinations? Check out our Best Red Dot & Magnifier Combos…or our standalone Best Red Dots articles.

I am a little confused by the Vortex magnifier that is on this list. The Micro3x Magnifier has been out for a couple of years now as the upgrade/potential replacement to the VMX-3T. From the review that I have read it has much clearer glass and a wider field of view. It is more expensive but still within the window of this group of magnifiers. Why wasn't it chosen instead of the older design?

I’ve had my HMX-3 behind a 510C for about a year and love it. It’s on a PSA KS47 and I’ve tried both ways as you describe. Either way works for me and I really have no preference although both eyes open is better for SA obviously.

If you dont wish to spend the money on a vortex or even the pa + mount check out the AT3 3x magnifer Their red dots are pretty darn good as well