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Twilight factor and twilight performance

Posted on 2016/07/072020/05/27 by Stephan Hohn

Calculation of twilight number and statement on twilight performance for binoculars The visual acuity of the human eye decreases in twilight to around a third of daytime visual acuity. The eye's sensitivity only increases for the blue spectral range. In order to be able to recognise details over long distances in twilight, binoculars with high magnification and corresponding [...]

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Exit pupil binoculars - calculate and explain

Posted on 2016/07/072020/05/27 by Stephan Hohn

Exit pupil of binoculars - meaning and calculation In addition to the twilight number, the exit pupil at the eyepiece of the binoculars is also very important for seeing in twilight (twilight vision). In theory, the larger the diameter of the exit pupil, the greater the image brightness in the eye. Calculating the exit pupil To determine the binocular exit pupil, calculate the ratio of the binocular magnification to the objective lens diameter: For 8x56 binoculars, calculate the [...]

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Field of view and viewing angle for optics such as binoculars and riflescopes

Posted on 2016/07/072020/05/28 by Stephan Hohn

Calculate field of view and viewing angle

Binoculars and riflescopes Field of view and angle of view The field of view of binoculars or riflescopes is specified either in degrees (angle of view) or in metres. The size of the field of view indicates the width of the terrain that can be observed through the binoculars at a distance of 1000 metres. In contrast, the field of view of riflescopes is usually specified for distances of 100 metres. Binoculars without a wide-angle function have a [...]

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Edge sharpness for binoculars

Posted on 2016/07/062020/05/28 by Stephan Hohn

For technical reasons, the image sharpness of binoculars decreases from the centre of the image to the edge (due to the shape of the lens). As a rule, it can be assumed that the higher the quality standard of the binoculars, the better the edge sharpness and the smaller the drop in sharpness. If the field of view is generously specified for inexpensive [...]

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Optical coating and coating of lenses and prisms

Posted on 2016/07/062017/05/15 by Stephan Hohn

Maximum optical performance thanks to optical coating of lenses and prisms When light hits a glass-air surface (e.g. with a roof prism), the reflection causes a loss of light. This results in a loss of image brightness, contrast and colour brilliance. This reflection can be reduced by coating the surface of lenses and prisms in binoculars or riflescopes with a thin layer of metal salts. Thanks to [...]

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Rubber armouring for binoculars

Posted on 2016/07/062020/05/27 by Stephan Hohn

Binoculars rubber armouring for better grip and additional protection Additional protection of the binoculars in harsh conditions is achieved by applying a hard-wearing rubber armouring to the binoculars housing. In addition to better protection against impact and shock, this also ensures that the binoculars can be held securely in wet or cold weather. Extract Binoculars with rubber armouring in the Optics Shop For you! [...]

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Nitrogen filling for binoculars

Posted on 2016/07/062020/05/28 by Stephan Hohn

Nitrogen filling for sealing optical devices such as binoculars and optical sights Temperature fluctuations can cause moisture to enter the housing of binoculars and cause the inner glass surfaces to fog up. Filling with dry nitrogen (nitrogen filling) reduces the moisture content during assembly and thus prevents the inside of the lenses from fogging up later. High-quality binoculars are completely sealed airtight after [...]

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Prism comparison of Porro and roof prisms

Posted on 2016/07/062020/05/28 by Stephan Hohn

Difference and comparison between porro prisms and roof prisms The design of binoculars is always determined by the type of prism used. Difference between prism systems left: Roof prism, right: Porro Porro prism Binoculars with the Porro prism design can be recognised by their relatively low height and wide design. Advantage: The greater distance between the two lenses promotes spatial vision. A graphical representation and [...]

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Aspherical lenses

Posted on 2016/07/062020/05/27 by Stephan Hohn

Increased optical performance through aspherical lenses The use of aspherical (non-spherical) lenses increases optical performance, especially at the edges. By changing the curvature towards the edge of the lens, light rays reaching the edge of the lens are also precisely deflected, resulting in a significantly sharper, high-contrast and detailed image across the entire field of view. Main advantage of aspherical lenses Through [...]

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Use of binoculars for spectacle wearers

Posted on 2016/07/062020/05/28 by Stephan Hohn

What spectacle wearers need to consider when buying binoculars! Half of the European population wear glasses either temporarily or permanently. Looking through binoculars with glasses reduces the field of vision by 50-60%. An eyepiece with dioptre compensation offers a remedy for short-sightedness or long-sightedness. If you wear glasses, you should therefore make sure when buying binoculars that these [...]

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Dioptre correction for spectacle wearers with binoculars

Posted on 2016/07/052020/05/27 by Stephan Hohn

Dioptre correction for spectacle wearers with different visual acuity The dioptre correction on the eyepiece is used to compensate for differences in visual acuity between the eyes. Dioptre adjustment for binoculars Many people have differences in the visual acuity of both eyes. For this reason, binoculars with two identical eyepieces with adjustment options are used to achieve a uniformly sharp image of the object (the differences between the two eyes [...]).

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Function of the eye - adaptation to light and darkness

Posted on 2016/07/052020/05/27 by Stephan Hohn

The function of dark adaptation and light adaptation of light or on the retina in the eye The retina of our eyes has two different types of sensory cells or receptors, on the one hand the cones (for day vision) and on the other hand the rods (for night vision). All photoreceptors are stimulated by the amount and spectrum of radiation. The cones are more sensitive to light [...]

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