Comparison Sigeta Spirit 8x25 WP vs BRESSER Nautic 8x25 WP

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 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.

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).

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 method of aiming the optics of binoculars (see "Type") for sharpness.

— Central. In accordance with the name, focus in this case is carried out using a regulator (usually a rotary handwheel) located in the central part of the binoculars, between the halves. When such a flywheel is turned, both optical systems are adjusted simultaneously — this is convenient, because. allows you to quickly reconfigure the binoculars for different distances. On the other hand, such models are more complex in design than separate ones, have more weight and less reliability.

— Separate. In models with this type of focus, each eyepiece is adjusted separately. This is not as convenient as the central control, but it allows you to reduce the weight, dimensions and price of binoculars, and also facilitates the creation of "protected" devices.

— Automatic. The name in this case is not entirely true: we are not talking about automatic adjustment of optics, but about a fixed focus. Such binoculars do not require focus during use — they allow you to clearly see all objects in the range from the minimum focus distance to infinity, and the observer's eye itself performs the necessary adjustment (similar to what happens when viewing objects at different distances with the naked eye). Models of this type are very convenient for observing on the move, especially when th...e distance to the observed object is constantly changing, as well as in situations where the exact location of the appearance of this object is unknown — they allow you to "target" as quickly as possible and without unnecessary movements. As a result, autofocus is considered optimal for watching sports, wildlife, and the like. The main disadvantage of autofocus can be called the fact that it noticeably tyres the eyes — especially when alternating between the naked eye and the use of binoculars.

The presence of a special gas in the body of binoculars / monoculars — usually nitrogen or argon. Due to its chemical inertness, such a gas does not oxidize internal parts (unlike the oxygen contained in the air). In addition, this function assumes the tightness of the case, which allows most of these binoculars to endure even diving under water (for more details, see "Dust and water protection"), and also protects the optics from the harmful effects of fog. All this has a positive effect on the reliability and service life of the device. In turn, the gas filler itself contains practically no water vapor — thanks to this, the lenses do not fog up from the inside, as happens with conventional models during temperature changes.