Many of those who follow the situation in the market of automatic small arms probably drew attention to a wide discussion that unfolded around the issue of the consumer qualities of new models. If in the opinion of the developers, small dimensions and high ballistic characteristics make the new models almost a dream subject and the top of perfection, then the professional arrows are mostly more restrained in assessments. Without questioning the technical merits of the weapons samples presented to their court, they note that their effectiveness is extremely low when firing at medium and long distances.
The optical scheme of most of the sights with a red dot consists of a small light source and an optical system that directs the radiation of the light source only toward the exit pupil of the sight. As a rule, it transmits the image without magnification, transforming the radiation of the light source so that when viewed through the sight the shooter simultaneously sees a clear image of the far-away plane and the aiming mark in the form of a small light spot.
In this case, the mixing of the eye arrow within the exit pupil of the sight does not affect the visible position of the aiming mark on the remote target. Thus, the shooter has the opportunity not to fix his eyes on the axis of the gun barrel and effectively use the binocularity of the eyesight. And to accurately aim, the arrow is enough just to aim at the target spotlight spot.
Important is the colour and the visible size of the aiming mark. Preference is its bright red colour due to the fact that in nature, virtually no objects of red colour. Therefore, such a mark contrasts prominently on the general background of objects, in addition, the red colour is psychologically perceived as a moment of danger and attention is first fixed on it.
As for the apparent size of the brand, its optimum value depends on the type of weapon. If for long-rifled rifled weapons intended for shooting at a distance of more than 150 meters, the size of the mark is desirable to have close to the maximum resolution of the eye (about 1 arcmin, i.e. about 3 cm at a distance of 100 m), then for hunting and short-barreled automatic weapons is more preferable brand with a visible size of about 10 angular. min., which corresponds to the resolution of the eye in low-light conditions and about half the size of the M-16 automatic rifle.
In simple and cheap models of sights with a red dot, the optical system is usually made in the form of a transparent spherical meniscus, on the concave surface of which a red reflecting mirror coating is applied. As a light source, a conventional red LED is used. The mutual position of the meniscus and the light source is chosen so that the aiming axis coincides with the axis of the light beam reflected from the meniscus, and the light source is in the focal plane of the meniscus and does not fall into the field of view of the sight. The shooter observes the target through a transparent meniscus.