Category Archives: BINOCULARS EXPLAINED

BINOCULARS EXPLAINED INDEX

Aperture  Armoring of binoculars           Aspheric Lenses           BaK-4 (barium crown)             Basic design of binoculars: Porro prisms or roof prisms         BK-7 (borosilicate)          Chromatic Aberration         Close focus       Coating of lenses     Collimation      Contrast    Depth of field      Dielectric Coatings       Diopter         Exit pupil           Eye relief         … Continue reading

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Optical glass

Three types of glass are currently used for making lenses and prisms: BK-7, BaK-4 and SK15. SK15 is the highest quality glass available and has only recently been introduced to optics of binoculars (expensive). I found only two brand names … Continue reading

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Lenses and prisms

The optical elements of a pair of binoculars consist of lenses and prisms and could be which could be as much as 16 elements in total. Lenses are the optical elements through which the light travel, from the big ones … Continue reading

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Eye relief

For every pair of binoculars, there is an optimal distance between your eye and the eyepiece, which is called eye relief. The eye relief of a binocular is the distance your eyes are allowed to be away from the eyepieces … Continue reading

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Depth of field

The “depth of field” of a pair of binoculars refers to its ability to keep objects further towards the background and closer towards the foreground in focus without you having to adjust the focus. Stated in another way: Once you’ve … Continue reading

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The twilight factor

Some manufacturers claim that a combination of the magnification and objective lens size makes a greater contribution towards image brightness in dim light than the diameter of the exit pupil. This is known as the “twilight factor”, and is calculated … Continue reading

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Close focus distance

Focusing at a distance is no problem for any pair of binoculars; focusing at close range, however, is a totally different matter. In the specification of all binoculars you will find detail on its close focus distance, expressed in feet/yards … Continue reading

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How to calibrate the binoculars for your personal use

The first thing you have to do is to twist the tubes or barrels of the pair of binoculars around its central axle until the two eyepieces fit exactly on your eyes and you can see a circular field of … Continue reading

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Field of view (FOV)

Another set of technical detail which is imprinted on the binoculars, could be something like this: 372 ft. at 1000 yds, as can clearly be seen in the image. This is the field of view, the width of the view … Continue reading

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Focusing mechanisms

The focusing mechanism of a pair of binoculars, by means of which the focus is adjusted when looking at an object through the binoculars, is found between the two barrels of the or/and at the top. This can either be … Continue reading

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