Better values for front lens, eyepiece, brightness, twilight factor and compensation become noticeable on the price. Binoculars cost 25-2000 Euro, in reasonable quality at least 150 dollars. For entry the sufficient.
First glance through my new lace binoculars I will never forget. It was a black redstart, who sang in the early morning light on the roof gable, vibrant full-throated and entire body. Every detail of the feathers could be seen well. A pair of binoculars is the most important tool for birding. Anyone interested in birds and their behavior, needs sooner or later one. Only with it you recognize relevant for determining details such as plumage color, Supercilium or beak shape. But what binoculars suitable for it? When choosing to get to some technical details not help. Magnification and lens diameter Getting information about the performance are on every binoculars a combination of numbers such as 10 x 40. The starting number is the image magnification – the example 10x – and describes how much closer an object appears to the viewer. A 100 meters distant white stork appears so great when he was only ten yards away when looking through the glass. To observe are 7- to 10-fold magnifications ideal. Higher values binoculars can not keep quiet enough, the image trembles and wobbles. Some manufacturers now offer combinations with switchable 10 and 15x magnification. After the multiplication sign is the diameter of the front lens – in this example 40 mm – depend two essential qualities of the: the light entering into the glass and the field of view. The larger the front lens, the more light the glass gathers. For Tagbeobachtungen suitable 20 till 32, for low light conditions 40 to 80 and more millimeters. Field of view, brightness and twilight performance are not immediately apparent addition specified important that need to be asked:
The visual field describes the size of the manageable range at 1000 meters distance. is greater the magnification, the smaller the vision or visual field and the more difficult is a target object to be found. Flying birds can be discerned better with a larger field of view.
The light intensity is calculated by dividing the front lens size by magnifying and multiplying the result by itself (in the example 40 by 10 = 4 x 4 = 16). The larger the number, the greater the intensity and the brighter and more detailed the picture is. The light intensity of the binoculars can only be exploited by a maximum dilated pupil at dusk, when the eyepiece has a large outlet opening. For smaller ocular exits less light and a darker image is the result.
The twilight factor describes the performance of the glass at dawn and should be 12 to 25 The higher the number, the brighter and brighter the image.
Special coatings of the lenses to reduce reflections also influence brightness and color fastness.
The visual quality of high-quality binoculars also characterized by high resolution and high contrast, the absence of disturbing stray light, a good depth of field, low color aberration, high edge sharpness of the image and lack of color fringes.