The possibility of manual
adjustment of the sight from parallax, by the user himself. For this purpose, the design provides a corresponding regulator.
Parallax in this case is a phenomenon when, when the eye deviates from the optical axis of the sight (from the center of the eyepiece), the aiming mark visible to the shooter also shifts, while the sight itself remains motionless. As a result, if the eye is not exactly in the center, the visible position of the mark does not coincide with the actual aiming point. This phenomenon is especially pronounced in optical sights (see "Type"), and many collimators are also subject to it, although not to the same extent (but "night vision" and thermal imagers are free of this drawback, since the mark is displayed on the built-in display).
To eliminate this phenomenon, a specific adjustment is used - parallax adjustment. It is usually done right at the factory. However, the sight can be adjusted from parallax only for a certain distance, and with significant deviations from this distance (more than 30% downwards or 60% upwards), this effect begins to manifest itself again. It can be compensated for by an ideal insert ("eye strictly in the center"), but even for experienced shooters this can be difficult, especially when shooting standing, offhand and in other uncomfortable positions. In light of this, some models also provide manual parallax adjustment - a regulator that allows you
...to set the adjustment distance at the user's discretion. In addition to the situations described above, this function will be especially useful for novice users, as well as for high-precision shooting at long distances.
Optical sights with parallax adjustment> can be equipped with a wide ring on the AO (Adjustable Objective) lens or a drum on the SF (Side Focusing) control unit, on which additional accessories for fine-tuning the focus in the form of wheels are installed.The total length of the sight.
This parameter is important primarily for optical sights (see "Type"). Such devices can be quite large — from
20 – 30 cm in the most compact models up to
40 cm or more ; and the distance from the eyepiece to the eye when aiming must be strictly defined. So before buying, it's ok to clarify whether it will be possible to correctly place the selected model on the weapon. But collimators, even the largest ones, are very compact, usually there are no problems with their installation, so in such models the length does not play a special role.
/-1.5 to +1.5/
