Optical sights are a necessary element in the toolkit of any firearms and bow user. And red dot sight is one of the most affordable and simple optical sights ever designed. If you want to learn how does red dot optic works, this article is for you.
What is a red dot sight
The red dot sight is an optical targeting device that projects an image of a red dot over the image of the target and thus assists aiming. Technically, such optic reflex sights are very simple therefore are available for almost any type of weapons including rifles, pistol guns, and even bows. Yes, that’s right: there you can buy a red dot bow sight too! Cool, yeah?
Principle of operation
Red dot sights work by overlapping together two images: one optical image comes from the target, and the other image is a projected miniature red dot. The shooter then aims by drawing the red dot on top of the target in the reticle. And that does the trick: the bullet or the arrow hits the target.
Now, what about the technical part? How does the red dot sight actually work? Look: a small battery-powered LED projects the image of the red dot to the semi-transparent mirror. This mirror reflects the projected red light towards the eye. Since the mirror is only semi-transparent, that is it can only reflect light coming from one side, but not from the other, the light coming to the sight from the target is not reflected and comes into the eye of the shooter unaffected. Hence, the weapon user sees two images combined into one: the target with a small red dot over it. Easy.
Depending on the actual red dot sight model, the details of the technical implementation of the above principle may vary. For example, red dot optics can have a spherical mirror that focuses and redirects light coming from the LED. Also, a special device called collimator can be used to narrow the beam of light produced by the LED. That is why red dot sights are sometimes called collimator sights.
The size of the red dot reticle depends on the particular model of the optical sight and on its settings. The red dot size is measured in MOA which stands for Minutes of Angle. The less the MOA value is, the smaller the red dot appears. Miniature red dots allow for better shooting accuracy since they do not overlap the target so much. At the same time, a too small red dot can be hard to see in the daylight, so you’ll need to find balance depending on your actual working conditions.
Advantages and disadvantages of red dot reflex sights
Surely, the red dot has its pros and cons, namely:
- Small and lightweight. You can mount a red dot to almost any weapon, including a bow.
- Quick targeting. Red dot are very easy to start using. Yes, you’ll need some time to make yourself aim with both eyes opened, but for most users this only takes a few minutes to accustom.
- Best at short and mid range. Red dot sights assist aiming at short and medium ranges. Longer ranges are possible too, but red dot must be used with a magnifier then.
- Can be quickly mounted and dismounted. This allows you to use one sight for all weapon set you have.
- No parallax distortion. You don’t have to center the red dot reticle in the sight. By design, red dot sights are parallax-free.
- Affordable. Red dot optics is among the lowest priced aim assistance devices.
- The red dot overlaps the target. Depending one the relative MOA size of the reticle and the target, the red dot can completely overlap the target effectively making it harder to aim, not easier. Make sure to select the right MOA size of the red dot or choose models with adjustable MOA.
- Red dot is a subject to weather conditions. Weather elements such as moisture, rain or dirt can hinder your aiming. Choosing models with a closed design partially solves this problem.
- Not suitable for longer ranges. While red dot sights are ideal for short and mid range, their performance at longer distances drops down drastically. Luckily, red dots can be used along with a magnifier, which is a relief if you are more of a ranger than a gunslinger.