Comparison Canon 18x50 IS All Weather vs Nikon Aculon A211 16x50

The magnification factor indicates how many times the image of any object in the eyepiece will be larger than what is visible to the naked eye. Standard values are 7x, 8x, 10x, 12x, 20x. The higher the magnification, the greater the degree of approximation and the further the distance from which one or another object can be seen through binoculars. On the other hand, increasing the magnification usually means decreasing the angle of view, and it can be very difficult to “catch” an object of interest (especially a moving one) through binoculars. In addition, with the same lens size, a model with a higher magnification will have a smaller exit pupil size and, accordingly, a lower aperture ratio (see below for more details). For models with multiplicity adjustment (see below), this item usually indicates the maximum value of this parameter. The magnification is the first number in traditional markings like 8x40 - this example corresponds to eight-fold optics. If there is a multiplicity adjustment (see below), the markings indicate the entire range - for example, 8-12x40.

The presence in the design of the device of an optical image stabilization system — similar to those used in lenses for photographic and video equipment. The effect of such stabilization is based on the use of movable lenses and gyroscopes, which monitor small tremors of the device and make the necessary adjustments to the operation of the optics so that the visible “picture” remains motionless. This function is especially useful at high magnifications, as well as when holding the device in your hands; at the same time, it significantly complicates the design and increases the cost, and also requires a power source (usually in the form of batteries).

The diameter of the area visible through binoculars / monoculars from a distance of 1 km — 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". Along with the angular field of view (see below), this parameter characterizes the space covered by the optics; at the same time, it describes the capabilities of a particular model more clearly than data on viewing angles. Models with magnification adjustment (see above) usually indicate the maximum field of view — at the lowest magnification and the widest angle of view. This information is often supplemented by data on the minimum value.

The angle of view provided by binoculars/monoculars and available to the eye of the observer. This parameter can be described as the angle between the lines connecting the two extreme points of the image visible in the eyepiece with the eye of the observer; in other words, this is the sector actually observed through binoculars (as opposed to the actual angular field of view described below). The greater the value of this parameter, the greater part of the observed space can be seen without turning the instrument. On the other hand, a wide field of view reduces the magnification factor (see above) — or significantly increases the cost of the device compared to more focused ones.

The section of the panorama that can be viewed through the eyepieces of binoculars. The higher the actual angular field of view, the wider the visibility of the optics. Note that the angular field of view has an inverse relationship with magnification. That is, the higher the magnification, the narrower the visibility (the smaller the real angular field of view). The actual angular field of view is calculated as follows: you need to divide the angular field of view (in degrees °) by the magnification factor. In comparison, the human eye has an angular field of view of 60 arcseconds (“). In terms of degrees, you get 150 °. Good binoculars provide a real field of view somewhere within 10 arcseconds. But it does not always make sense to chase after large indicators of the real angular field of view. The fact is that when viewing a large section of the panorama, the edges of the image receive noticeable distortion.

The smallest distance to the observed object, at which it will be clearly visible through binoculars / monoculars. All such optical instruments were initially created for observing remote objects, therefore, not all of them are able to work at short distances. When choosing a model for this parameter, one should proceed from the expected observation conditions: ideally, the minimum focus distance should not be greater than the smallest possible distance to the observed object.

A complex indicator that describes the quality of binoculars / monoculars at dusk — when the illumination 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 through binoculars is determined primarily by the magnification of the optics, and in night light, by the diameter of the lens (see below); 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 8x40 binoculars, the twilight factor will be the root of 8x40=320, that is, approximately 17.8. In models with power adjustment (see above), the minimum twilight factor is usually indicated at the lowest magnification, but data is often given for the maximum. 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 lenses and prisms, the use of antireflection coatings, 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 below) squared; the higher this number, the more light the binoculars/monoculars let through. At the same time, this indicator does not take into account the quality of lenses, prisms and coatings used in the design. Therefore, comparing the two models in terms of relative brightness is only possible approximately, since even if the values are equal, the actual image quality may differ markedly.

The presence in binoculars / monoculars of the function of diopter correction. This feature will be very useful if you wear glasses due to nearsightedness or farsightedness. By setting the required number of "plus" or "minus" diopters on the adjustment scale, you can look into the eyepiece with the naked eye and see a clear picture — the optics of the device will provide the necessary correction. It is much more convenient than watching through glasses. However one should not forget that the correction range (see below) is usually small, and in case of serious visual impairments, the capabilities of the binoculars may not be enough; but such situations are still quite rare. In binoculars (see "Type"), this adjustment is usually carried out for each eyepiece separately, because The diopters required for each eye may also be different. Features of the correction control depend on the type of focus (see below). With separate focus, each eyepiece is adjusted with its own regulator, with the central one of the halves (usually the left) is regulated using a common focus handwheel, and the second with a separate knob on the eyepiece (although here there are separate regulators on both eyepieces).