Comparison Barska AR6 Tactical 1-6x24 vs Barska Contour 3-9x42

— Optical. Classic optical sights; in essence, telescopes of a special design with sighting reticles applied in the field of view. It is precisely these “pipes” that are traditionally used for sniper shooting - both high-precision and “fast”, for example, in hunting (however, “pipes” are placed in a separate category). They can have both a small and a very high degree of magnification (in many models this parameter is also adjustable), provide the ability to make adjustments vertically and horizontally, and the marking of many sighting reticles allows you to make such adjustments on the fly without reconfiguring the sight itself. But optics are not suitable for the fastest possible shooting offhand: aiming takes a lot of time, and the field of view is limited. In addition, using such a sight requires a certain skill - so, ideally, the shooter’s eye should be located on the optical axis (for more details, see “Parallax adjustments”) and at a strictly defined distance from the sight. Note that the sights themselves do not require batteries, but power may be required for some additional functions, such as illuminating the reticle. In the dark, the optics themselves are practically useless; only a few models are compatible with NVGs.

- “Penchor”. Closed-type optical sights, originally developed for driven hunting. Their characteristic feature is the ability to make quick shots offhand while maintainin...g a large field of view for the shooter. Externally, the “drivers” are often compact, and the size of their lens is most often no larger than the “landing size of the rings.” Such sights are equipped with the ability to adjust the magnification (on average 1x – 4x, but the maximum magnification can be higher, but the minimum magnification is not more than 2x). The main task of the “driver” is to guide a rapidly moving target during daylight hours, both at a short distance and at a medium distance, firing with target recognition (aimed shooting is ensured at a distance of 5 - 150 m). They are often equipped with a backlight module, which at 1x magnification turns the sight into a collimator sight and allows you to quickly target an object near the shooter and not lose the aiming mark in the thicket of the forest when searching for a target.

— Collimator. Sights based on optical systems in which the aiming mark is not fixedly applied to the lens, but is projected onto it using a special light source. Despite the external similarity of some of these models with traditional optics, collimators have actually the opposite specialization: they are designed for short distances and the ability to quickly fire offhand. Thus, such devices usually do not provide magnification or narrow the field of view (there are exceptions, but they are extremely rare), and the aiming mark always more or less coincides with the actual aiming point, regardless of the position of the working eye relative to the sight. From the shooter's perspective, it looks like when the head moves, the mark also moves, remaining on the target. True, despite the common misconception, the collimator design itself does not guarantee the absence of parallax (see “Parallax adjustments”); however, when this effect is present, it is usually weakly expressed and has almost no effect on shooting accuracy, and there are also completely parallax-free models. The main disadvantage of collimator collimators is that they require battery or battery power.

- Prismatic. At its core, it is a compact hybrid of an optical and collimator sight. From classical “optics”, such sights borrowed a lens system that provides slight magnification, and an engraved aiming reticle etched on the prism glass itself. However, unlike traditional optical sights, they have a more compact prismatic wrapping system. Externally, prismatic-type models are similar to closed collimator sights. They also use reflective illumination of the reticle and provide an integrated mount, mainly for the Weaver rail. Most prismatic sights have the ability to change the reticle and select the illumination color (usually red or green). Sights of this type provide quick target acquisition, and they are designed for accurate shooting at short and medium distances. — Magnifier. Optical devices installed in front of sights to increase the zoom ratio, thanks to which the shooter can see distant objects more clearly and aim at targets faster. Magnifers are mainly used in conjunction with collimator sights (see the corresponding paragraph). Their magnification ratio varies from 3x to 7x. Often such optical devices come with a special mount that allows you to instantly “throw” the magnifier to the side for aiming directly through the collimator.

The magnification provided by the scope. This parameter indicates how many times the image of any object in the field of view will be larger than that visible to the naked eye. For models with the ability to change the ratio (see below), the entire available range of adjustment is indicated.

Modern sights can be produced in a wide variety of magnifications, the only exceptions are collimators (see "Type") — they usually give a magnification of 1x, that is, in fact, do not change the visible image in any way; higher values are extremely rare and usually do not exceed 5x. In other types of sights, the maximum magnification from 2x to 5x means that this model is designed for very short distances of application. In turn, the most "far-sighted" devices can provide an increase of 17 – 20x and even more.

Note that a high magnification not only allows you to better view distant and small objects, but also narrows the field of view. With this in mind, the main criteria for choosing a sight by magnification are the expected distances of use, as well as the size and type of targets. Detailed recommendations on this matter for different situations can be found in special sources. And here we note that the degree of magnification significantly affects the cost of the sight — both in itself and due to the fact that larger (and, acco...rdingly, more expensive) lenses are desirable for "long-range" optics. At the same time, a low magnification is not necessarily a sign of a cheap device — in itself, it only means that the sight is designed for short distances and a wide field of view.

As for models with variable magnification, the wider the adjustment range — the more advanced and versatile the device is, the lower the likelihood that there is no suitable setting for a particular situation. On the other hand, expanding the range complicates the design, making it more expensive and less reliable.

The diameter of the objective is the front lens of the sight. This parameter is also called "aperture".

This parameter is important primarily for optical sights and their specialized varieties — "night lights" and thermal imagers (see "Type"). The larger the lens, the more light enters it, the higher the image quality and the more efficient the device will work in low light, but the more expensive such optics will cost. It is worth noting here that the requirements for the aperture also depend on the degree of magnification: in other words, especially large lenses are not required for low magnifications. Therefore, relatively small entrance lenses, with a diameter of 25 – 35 mm and even less, are found in all price categories of classical optics — from low-cost to top. And you can compare by aperture only models with the same maximum magnification, and even then it’s very approximate — it’s worth remembering that image quality also depends heavily on the overall quality of the sight components.

In turn, for night sights, especially those based on image intensifier tubes (see "The principle of operation of night vision devices"), a large aperture is fundamentally important. So a diameter of 36 to 45 mm is considered very small for such devices and is found only in some digital models, while most nightlights are equipped with lenses of 46 mm or more.

As for collimators, the size of the space that enters the scope depends mainly on the aperture. Moreover, the actual visible size can be changed by setting the sight closer or farther to the eye — the principle of operation of collimators makes this possible. Note also that for models with lenses of a rectangular or similar shape, the size of the lens is usually indicated diagonally.

The diameter of the exit pupil created by the optical system of the sight.

The exit pupil is called the projection of the front lens of the lens, built by the optics in the region of the eyepiece; this image can be observed in the form of a characteristic light circle, if you look into the eyepiece not close, but from a distance of 30 – 40 cm. The diameter of this circle can be calculated by dividing the lens diameter by the multiplicity (see above). For example, an 8x40 model would have a pupil diameter of 40/8=5mm. This indicator determines the overall aperture of the device and, accordingly, the image quality in low light: the larger the pupil diameter, the brighter the “picture” will be (of course, with the same lens quality, because it also affects the brightness).

In addition, it is believed that the diameter of the exit pupil should be no less than that of the pupil of the human eye — and the size of the latter can vary. So, in daylight, the pupil in the eye has a size of 2-3 mm, and in the dark — 7-8 mm in adolescents and adults, and about 5 mm in the elderly. This point should be taken into account when choosing a model for specific conditions: after all, high-aperture optics are expensive, and it hardly makes sense to overpay for a large pupil if you need a scope exclusively for daytime use.

The offset is the distance between the eyepiece lens and the exit pupil of an optical instrument (see "Exit Pupil Diameter"). Optimum image quality is achieved when the exit pupil is projected directly into the observer's eye; so from a practical point of view, offset is the distance from the eye to the eyepiece lens that provides the best visibility and does not darken the edges (vignetting). A large offset is especially important if the sight is planned to be used simultaneously with glasses — after all, in such cases it is not possible to bring the eyepiece close to the eye, and it must be at some distance from the glasses so as not to hit the glass due to recoil.

The diameter of the area visible through the sight from a distance of 100 m — in other words, the largest distance between two points at which they can be seen simultaneously from this distance. It is also called "linear field of view". This indicator is more convenient for many users than the angular field of view (the angle between the lines connecting the lens and the extreme points of the visible image) — it very clearly describes the capabilities of the device.

In sights with magnification adjustment (see above), both the entire range of width — from maximum to minimum — or only one value of this parameter can be indicated. In the latter case, the largest width of the field of view is usually taken, at the minimum magnification.

A complex indicator that describes the quality of any optical system (including sights) at dusk — when the lighting is weaker than during the day, but not yet as dim as in the deep evening or at night. It is primarily about the ability to see small details through the device.

The need to use this parameter is due to the fact that twilight is a special condition. In daylight, the visibility of small details is determined primarily by the magnification of the optics, and in night light, by the diameter of the lens (see above); at dusk, both of these indicators affect the quality. This feature takes into account the twilight factor. Its specific value is calculated as the square root of the product of the multiplicity and the diameter of the lens. For example, for an 8x40 scope, the twilight factor would be the root of 8x40=320, which is approximately 17.8. Models with adjustable magnification (see above) usually indicate the minimum twilight factor corresponding to the minimum magnification.

The lowest value of this parameter for normal visibility at dusk is considered to be 17. At the same time, it is worth noting that the twilight factor does not take into account the actual light transmission of the system — and it strongly depends on the quality of the lenses, the use of antireflection coatings (see below), etc. Therefore, the actual image quality at dusk for two models with the same twilight factor may differ markedly.

One of the parameters describing the quality of visibility through an optical device in low light conditions. Relative brightness is denoted as the diameter of the exit pupil (see above), squared; the higher this number, the more light the sight lets through. At the same time, this indicator does not take into account the quality of the lenses and their coatings used in the design. Therefore, comparing two sights in terms of relative brightness is only possible approximately, because even if the values are equal, the actual image quality may differ markedly. Also note that it makes sense to pay attention to this parameter only if the sight is planned to be used at dusk.

As for specific values, in the "dimest" models, the relative brightness does not exceed 100, in the most "bright" it can be 300 or more. Detailed recommendations regarding the choice of this parameter for certain conditions can be found in special sources. Here it is worth mentioning that the relative brightness is not directly related to the price category of the sight: models similar in this indicator can vary significantly in price.

The division value of the turrets used in the sight to enter corrections.

The increment value for the correction turret is the angle that the point of impact shifts when rotated by 1 click (“click”). In this case, this angle is indicated in MOA — minutes of arc. For more information about this unit, see "Measuring units of the sight"; and the lower the division value, the more accurately you can set up the sight initially and make corrections in the future. For example, if this indicator is 0.5 MOA — each click will shift the point of impact by about 1.46 cm for every 100 m of distance (that is, 2.91 cm at a distance of 200 m, 4.4 cm at 300 m and so on); and 0.25 MOA will already give only 7.3 mm per click for every 100 m.

The smaller the step and the more accurate the adjustment system, the more expensive it is. Therefore, when choosing, it is worth taking into account the features of the planned application — first of all, the size of the targets and the distance to them; detailed recommendations on this matter are in various manuals on shooting. If we talk about specific values, then the mentioned 0.5 (1/2) MOA are typical mainly for inexpensive and medium scopes, 0.25 (1/4) MOA is a pretty good indicator, and the advanced optics itself allows adjustment in increments of 0.125 (1/8) MOA.