Day optical devices have several important characteristics that should guide the choice of instrument for application in certain conditions.

1. The magnification (zoom). The feature shows how the use of the device "increases" or "closer" overlooked items. For example, if you use the model, "magnifying" the image 10 times, the object located a kilometer away from us will be visible as naked eye we see the object, remote from us at 100 meters. Typically, the ratio quantitatively indicates the name of the model in the first place. Although this feature is primarily interested in user when choosing a device is necessary to pay attention to others.

2. The diameter of the entrance lens of the lens determines how much light it collects and guides the lens into the optical system of the device. (The flow is collected and directed light is greater, the larger the diameter of the entrance lens). Typically, the diameter of the entrance lens is quantitatively specified in the model name, which is in second place after specifying the multiplicity. For example, in the model name indicates the 10x50 lens diameter 50 (mm). (10 is a quantitative indication of the previous characteristics, multiplicity).

3. The diameter of the entrance pupil. Entrance pupil is called the circle of light you see in the eyepiece is focused on the light device when viewed from a distance of 20-30 cm Size (diameter) of this light spot are a measure of how much light is able to pass the eyepiece, and therefore how bright it will be visible in the device image. The diameter of the inlet of the icon is variable. Especially when the bright light of the entrance pupil is narrowed, and the lack of lighting - is expanding. In a medium, the diameter of the entrance pupil equals the diameter of the lens divided by the index of multiplicity. In the example with a 10x50 model, the diameter of the entrance pupil is equal to 5 mm: 50mm/10 = 5. Since the illuminance fluctuations of the sizes of the entrance pupil, it is necessary when choosing a model to take into account the conditions in which you will use the device. As a rule, preference is given to instruments with a larger diameter of the entrance pupil.

4. The aperture ratio (an index of brightness, the relative brightness). This comparative feature is a measure of the effectiveness of the device in low light conditions of the room or area. Aperture equal to the diameter of the entrance pupil squared. Ie, if the diameter of the entrance pupil of 5 mm, the aperture is 25 mm square, the larger the aperture, the model is more efficient in poor light conditions.

5. Field of view is called the width of the panorama seen through the optical device. Characteristic is expressed either in angular units (field of view equal to the size of the angle obrazuemogo two imaginary rays emanating from the eyeball of the observer to the two extreme points of the panorama) or linear (as the width of the panorama, visible from 1 km). The field of vision is smaller, the higher the multiplicity.

6. Resolution - a property of the device to distinguish small details of an image. The higher the resolution, the more info (details) You will be able to consider using this model the subject. The characteristic is measured in angular units (seconds) or in lines per mm (as the number of distinguishable lines per mm width of the image).

7. Enlightenment optics. Characteristics of antireflection coatings. When choosing a model it is important to pay attention to the quality of his so-called antireflective coating. These coatings are designed to reduce the effect of reflection and absorption of light by the optical parts of the device, as these physical processes have a negative impact on image quality. Antireflection coatings are described by color and number of layers poluchaemogo enlightenment, the spectrum of the transmitted light and the color tones of the image. For example, the enlightenment given by the lenses red well miss blue, Indigo and violet light rays and the resulting image has in this case is not particularly desirable green or blue tint. Most natural colors can be seen in the device, an antireflection coating which gives multi-layer coating on a greenish hue.

"RONBO.RU" Moscow
2007