Red dot, reflex, holographic, ACOG…When talking about the different types of electronic, (usually) non-magnified sights for our firearms, are we using the correct terms, and does it matter? So often I hear people use the words interchangeably. I’ve even heard people describe their non-Trijicon as an ACOG. Though, I personally don’t believe this is as serious as misusing the terms mag vs. clip—there are actual differences between the different types of sights.
What is a Red Dot Sight?
‘Red dot’ is the general term we use to refer to any type of gun optic that projects an illuminated red or green dot (or various other reticle shapes) on a target. Some may have more than a just a simple dot as an aiming point. Some offer a Chevron, crosshair, circle and a circle with dot.
It is a common misconception that a red dot sight is the parent category for any of these similar sights. A red dot sight is actually a type of reflex sight and a holographic sight is technically neither!
Is your mind blown yet? Let me explain…
The way we group these illuminated sights is by how they operate. Reflex sights are reflective sights and use a traditional lens, while holographic sights use lasers. Reflex sights are further broken down into two types—open and tube. The tube reflex sights is a true red dot sight.
A reflex sight utilizes a reflective glass lens to collimate light from an LED to serve as an aiming point while allowing the user to see the field of view simultaneously. The reflective design of a reflex sight is simplistic, consisting of two to three base components—objective lens, light emitting diode, and an etched diaphragm (if applicable.) The objective lens or objective aperture of a reflector sight is a transparent lens the shooter looks through while aiming. The lens is usually set at an angle to redirect collimated light, the reticle, towards the shooter’s eye. The inside surface of the lens facing the shooter is lined with a reflective coating to project the reticle toward the eye of the shooter. The outside surface of the lens facing away from the shooter is coated with an anti-reflective coating to improve reticle visibility. The light emitting diode is the source of the reticle image. Using only the LED to generate the reticle creates a simple dot. Incorporating an etched diaphragm stops the passage of light except through the aperture. As light from the LED is masked off, the remaining light takes shape of the design of the aperture, generally the shape of a reticle. Reflex sights fall into two categories—open and tube sights.
A true red dot sight is a reflex sight enclosed in a tube. They offer a brighter reticle than open sights and open reflex sights provide a wider field of view and unlimited eye relief. Open sights are better for faster target acquisition and are more comfortable for aiming with both eyes open. Some shooters find that tube sights are generally more accurate than reflex sights at 50 yards and over. Both open and tube sights are adaptable and will work on both rifles and handguns; however, mini reflex sights are great for handguns and fast-moving shooting competition like 3-Gun. Tube-style red dot sights are perfect for rifles, shotguns and other long guns and target shooters.
If you are hesitant about buying a red dot sight due to the lack of magnification, you need not worry. Most reflex sights, both tube and open, are magnifier- and night vision-compatible.
What are the Differences in Reticles or Aiming Points?
Reticles are traditionally designed as a series of lines, like the simple crosshair shape. These lines are called subtensions, measured in Minute of Angle or MOA. MOA determines the how much of the target the subtensions cover. Dot sights are usually 1 to 5 MOA. Larger dots cover more of the target and are better for quick acquisition of a target at closer ranges. For example, a 3 MOA dot will cover 3 inches of the target at 100 yards. At 200 yards, it will cover 6 inches of the target.
MOA is broken down like this:
1” at 100 yards, ½” at 50 and 2” at 200 yards and so on…
Some reflex and red dot sights have multiple reticle options. For example, Firefield’s tube-style red dots have a simple dot or dot with circle, while some of the reflex sights have multiple reticle choices. The Impact has four—5 MOA dot, 3 MOA dot with 50 MOA circle, 3 MOA dot with 50 MOA crosshair and a 3 MOA dot with 30 MOA circle/crosshair.
The single dot focuses only on the target and allows a wide field of view for better situational awareness. The dot with the ring is good for self-defense and close ranges, while the crosshair reticle is best utilized for mid to longer ranges. Different reticle choices let you use your red dot in a variety of different shooting situations—from self-defense to competition.
Some reflex and tube red dot sights have green illumination—we still refer to these sights as “red dots.” Some offer both, allowing you to switch between daytime and night time. Green is more visible in bright sunlight than red is.
From 1996 to 2017, EOTech held the monopoly on holographic weapon sights. Their outward appearance looks like the hundreds of other open reflex sights on the market, yet, internally they operate differently.
From EOTech’s website:
The holographic sight uses laser-driven holographic technology. It constructs a 2 or 3-dimensional image of a reticle, and the laser illuminates the hologram. Then the viewer looking through the sight window can see the reticle image in the distance, at the target plane.
These sights do not require any type of anti-reflective coating and offer a super-bright aiming dot. However, holographic red dots are more complex, drain batteries quicker and have a higher price tag than reflex sights.
Choosing which one is right for you depends on what type of gun you have, your purpose for purchasing a red dot sight and your budget.
Do you have a red dot sight? Tell us what you like and don’t like about it in the comment section. If you do not own a red dot sight, leave your questions below and we will do our best to help you.
See the following buyer’s guide for help with choosing the right scope for you: