Unmagnified Optics: Red Dot Vs Holographic Vs Prismatic Sights

Post Update 10/28/2022, First Published: Apr 15, 2020.

M1 Carbine Primary Arms Red Dot
Even older firearms like the M1 Carbine can find new life with the simple addition of a reflex sight like this Primary Arms Red Dot.

U.S.A. -(AmmoLand.com)- Reflective optics for artillery have been around since before World War One. With the massive rounds of the Great War, it makes sense – who would want to put their eye next to a scope ocular on a rifle with enough recoil to give shooters a black eye?

At first, these ambient light and half-mirror, “powered” reflex sights were confined to artillery and aircraft. They were simply too bulky and too daylight-dependent for small arms use. After World War Two, reflective optics were offered for sporting guns but were not considered suitable for individual military weapons.

Early Red Dot Armson OEG
Early red dots like this Nydar Model 47 didn’t catch on initially.

The first “red dot” in relatively wide military use was actually an Armson OEG (occluded eye gunsight), a fiber optic presenting a bright dot to the dominant eye but occluding the target from it. The occlusion guaranteed a high-contrast aiming point, while the non-dominant eye would see the target, and the brain would superimpose the two for a sight picture. Although useful for short-range aiming and quick in use, OEG sights did not gain overwhelming popularity.

Armson OEG Early Reflex Sight
The Armson OEG early Reflex Sight is seen here with an M16 carry handle mount.

Around the end of the 20th century, the battery-operated Aimpoint red dot sight went mainstream with the US military as the M68 Close Combat Optic. Unlike a reflector sight that used a flat half-mirror and a lens-collimated optical source outside the line of sight, the M68 uses a curved semi-reflective mirror to direct the reticle toward the shooter’s eye. The use of a single-wavelength LED permits a long battery life and also allows the passing of all other wavelengths of light through the half-mirror.

Wolf A1 SBR Aimpoint M68 556
A civilian version of the Taiwanese T91 sits with an AimPoint M68 CCO on top.

Advantages: efficient use of battery power, rapid target acquisition, lightweight, unlimited eye relief. The arbitrary eye placement distance is greatly helpful with using red dots on handguns. These sights are tolerant of off-center eye placement too, but they are not parallax-free. The amount of point of impact shift can be negligible and can be as much as 10 MOA, depending on the sight and the distance. Usually, the shift angle is greater up close, translating into a less actual point of impact offset: good enough for defensive work. Open emitter sights are lighter and offer wider fields of view, while tube sights better protect the emitter lens from dust and water droplets which would distort or attenuate the LED forming the reticle. Originally, red dots were limited to very simple reticles, but more sophisticated rangefinding reticles have recently become available at some cost in battery life.

GLock G34 Primary Arms Red dot
The Glock G34 is a breeze to shoot with a quality red dot like those from Primary Arms.

Today, the battery life in the tens of thousands of hours is typical for red dots, so that’s not a serious issue. The main disadvantage: the curved half-mirror causes reticle distortion for shooters with astigmatism. Most people have some astigmatism in their eyesight: the eye doesn’t focus on horizontal and vertical lines quite the same way. Between the pupil being contracted in bright light and corrective lenses, we don’t normally see the effect much. In low light, with the pupils open all the way, or in the peripheral vision where the corrective glasses aren’t as effective, astigmatism becomes more prominent, and the nice sharp red dot suddenly turns into a vertical line or a fuzzy blob, making precise aiming impossible. For people with near-perfect eyesight, that’s not a problem, while most older users would be affected.

Holosights are incredibly fast and work with human nature by coming into focus when a shooter looks past the reticle at their target.

Holographic sights to the rescue! Numerous EOTech sights and newer generation Vortex UH1 use holographic film in the line of sight to present a reticle. Pluses: greater reticle clarity than the red dot, untinted window, and much greater resistance to distortion due to astigmatism. The downside: holograms require laser illumination, reducing battery life and increasing the bulk of the sight. With EOTechs, a significant shift of zero in hot or cold weather has been confirmed in older models, but that issue has been corrected in new models. Lower-end red dots also suffer from it, while high-end red dots are less affected. UH1 gets around it by moving the entire rigid optic and laser assembly to adjust zero and managing to reduce thermal shift to negligible values. Holographic sights also offer unlimited eye relief and a higher degree of resistance to parallax than red dots. They can be compatible with night vision. Battery life is inferior to red dots but superior to illuminated scopes: 500 to 1000 hours is typical.

Swampfox Blade1x Prismatic Reflex
Prismatic optics like the Swampfox Blade are incredibly clear.

Prismatic scopes date back the furthest, being used with machine gunners and snipers around World War One. The unmagnified prismatic scopes are a far more recent phenomenon. These optics use Porro prisms similar to binoculars to bend the light path and create a focused sight picture within a relatively small volume. They are smaller than equivalent refractive straight-line scopes but can be surprisingly heavy. The major pluses of prismatic scopes are the clarity of the etched reticle and the ability to function without a battery, along with the option of using a complex BDC reticle. Reticle distortion from low-light astigmatism is not a problem, making these preferable for older users. Not all makers go with complex reticle designs: Vortex Spitfire uses a center dot with two concentric rings around it. Their emphasis is on rapid close-in performance.

SIG MPX Primary Arms Cyclops
SIG’s MPX, a Gentech suppressor and a Primary Arms Cyclops prismatic optic are a hell of a combo.

While using almost the same optics, Primary Arms Cyclops employs a more sophisticated BDC reticle to enable range-finding and drop compensation to several hundred yards. Without magnification, the makers must find a balance between features and simplicity to avoid cluttering the field of view. Swampfox Blade, a new design with impressively sharp glass, tried to nail that perfect compromise with the emphasis still on CQB. While prism scopes have long eye relief, they are far more restricted than red dot and holographic sights. Battery life is also shorter since the LED illuminator has to light up black etched elements. White reticles were once tried by FN for their P90 sight and found lacking in contrast, so the trade-off between the contrast without illumination and adequate brightness for two-eye aiming remains. Typical battery life is similar to holographic sights thanks to using more efficient LEDs rather than lasers.

At this time, all three types of unmagnified sights have clear strengths and thus preferred niche uses. The good news is that there are more good options on the market than bad. So shooters can confidently go with a trusted company regardless of which optic they choose.

Primary Arms SLx Advanced Rotary Knob Microdot Red Dot Sight

Primary Arms SLx Advanced Rotary Knob Microdot Red Dot Sight
Primary Arms SLx Advanced Rotary Knob Microdot Red Dot Sight

EOTech XPS2-2 Holographic Weapon Sight

EOTech XPS2-2 Holographic Weapon Sight
EOTech XPS2-2 Holographic Weapon Sight

Primary Arms SLx Compact 1×20 Prism Scope – ACSS-Cyclops

Primary Arms SLx Compact 1x20 Prism Scope - ACSS-Cyclops
Primary Arms SLx Compact 1×20 Prism Scope – ACSS-Cyclops

About Oleg Volk

Oleg Volk is a creative director working mainly in firearms advertising. A great fan of America and the right to bear arms, he uses his photography to support the right of every individual to self-determination and independence. To that end, he is also a big fan of firearms.

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Haven’t the Chinese done enough to us lately. stop buying their stuff.


Try buying a floor jack made in the USA. Or tools made in the USA. And when you do find something made in the USA we are treated to ridiculously high prices and in many cases LOWER quality. It sucks.


Red dot seemed to be a great direction for me, but then after using one (sig sauer Romeo5) with a Vortex 2x magnifier, I realized that my astigmatism was over powering my visual acuity. I still use it, but have taken the magnifier off, put iron sights back on and use in tandem with the Red Dot. Great for some, not for all. An expensive lesson. Will probably replace with a 1- 8 scope on the AR.

Arizona Don

Buy nothing made in China!


The people of China are not the problem. Their governing “authorities” are. Just like HERE where psychopaths are in control. As for buying from China? Tell me where to get a prism site like the Primary arms one that is made in the USA and I’ll scoop it up.


Size of the dot matters, as does intensity. Aimpoint Pro, 2moa dot. No problem ringing the 8″ gong at 300yrds, and have astigmatism in both eyes. Tried the rest. Other than a decent scope, it’s Aimpoint or nothing.




How about a chart that shows what was talked about? I read the article twice and still don’t know which I should get.


Red Dots Every time I start to think about how good red dots are with both eyes open . . . . . . . . I then start to think about how pissed off I would be if I had to keep my 1-6 LPVO at 1 power. Don’t get me wrong, it sits there all the time set at 1 power waiting for trouble . . . but when out in the world things get looked at at 3 power most of the time and then dialed to 6 as the want and need arises. Keeping it at… Read more »


You totally ignored that the SwampFox Blade has shake on illumination. The illumination goes off after a short time and comes back on when you pick up the gun. Saves and extends battery life!


A civilian version of the Taiwanese T91 sits with an AimPoint M68 CCO on top”

The UPPER may be the T91, but that LOWER has a different color and if you look close at the logo it has 1776 on it. I can’t imagine a Taiwanese lower having 1776 on it unless someone had it laser engraved.


What is the brand of the M1 in the first photo?


But those “stabilizing arm braces are SO g**!!!