Comparison Arsenal 7x50 NBN05-0750 vs Arsenal 7x50 NB61-0750

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 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 binoculars / monoculars are planned to be used simultaneously with glasses — because in such cases it is not possible to bring the eyepiece close to the eye.

The presence of a rangefinder in the design of binoculars / monoculars. Rangefinder, as the name implies, allows you to measure the distance to a specific object; but the specific methods of such measurement may vary. The simplest and most common variant is the reticle visible in the eyepieces; such rangefinders are inexpensive and work without batteries. On the other hand, the very procedure for using them is not very convenient, because requires knowledge of the dimensions of the object being used for measurement, as well as the ability to apply certain formulas. Active laser rangefinders are more convenient: with such a device, it is enough to point the binoculars mark at the target and press the button — the automation will do the rest. Their main disadvantage is the high price; in addition, the laser requires a power source to operate.

The presence of a compass in the design of binoculars (see "Type"; in monoculars, this function is practically not found for a number of technical reasons). A compass can be useful for navigating the terrain, especially when you are away from civilization — for example, during a hiking or hunting trip. In most cases, it is made in the form of a separate scale with an arrow installed in the upper part of the case; usually such models are professional, and the built-in compasses are not inferior in accuracy to ordinary tourist ones. And in the most advanced devices, the compass scale is superimposed directly on the image visible in the eyepieces — this is very convenient when determining azimuths for individual objects.

The presence in the design of the binoculars / monocular socket for attaching an adapter for a tripod(the adapter itself is not included in the kit, unless otherwise indicated). This feature is especially important for high magnification models (see above): they are usually heavy, making it difficult to hold stable in your hands, and at high magnification, even slight shaking can make observation impossible. In addition, mounting on a tripod is convenient for constant observation of a certain place, and such observation does not always require high magnification. Therefore, even fairly small devices can have the possibility of attaching an adapter. The adapters themselves can be designed for different sizes of tripod mounts — this must be taken into account when choosing such a model.