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High Grade Optical Components
The key criterion for excellent sharpness, contrast and light intensity is the quality of the prisms and lenses. OLYMPUS are a world-renowned trademark and synonymous with optical precision.
Want to know the definition for all those baffling technical terms and abbreviations? Just choose a category and start browsing, or download it (Adobe Acrobat Reader required). |
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The A to Z for Binoculars
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A
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Angle of view/Field of view
The angle of view is measured in degrees and reflects how wide an area you will be able to see with the binoculars. It is also referred to as the field of view, and can be expressed as the width of the viewing area in metres when viewed from a distance of 1000 metres. A wider field of view makes it easier to observe sports events, wildlife and other moving subjects. With the 8x25 PC I for instance, the field of view is 105 metres at 1000 metres. But with the 7x35 DPS I it is 162 metres at the same distance.
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Aspherical lenses
| Precisely tooled aspherical lens elements prevent distortion and guarantee plasticity, sharp contours and bright pictures. Aspherical lens technology is used in numerous OLYMPUS binoculars. |
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B
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BaK-4 prisms and lenses
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Precisely ground prisms and lenses made of brightness-enhancing barium crown glass (BaK-4) ensure clarity and brightness to the very edge of the field of view. OLYMPUS offers an extensive range of high-quality binoculars with BaK-4. |
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C
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Coating
A thin layer of a substance which is usually evaporated and baked on the lens surfaces to reduce reflection and increase light transmission.
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Contrast
The difference in intensity between the lightest and darkest image viewed through the optical system.
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D
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Diopter adjustment
All OLYMPUS binoculars have a central focusing knob, plus a separate diopter adjustment mechanism on one eyepiece. This individual eyepiece adjustment permits users to compensate for vision differences between their eyes and will produce in-focus images for each eye.
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De-alignment
An indication that the lenses are jarred out of position, decreasing the quality of viewing.
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E
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Exit pupil size
Exit pupil size refers to the diameter of the image that emerges from the eyepiece. The larger the image, the greater your ability to see in low-light situations. Exit pupil size can be determined by dividing the diameter of the objective lens by the magnification. This gives you the size of the exit pupil in millimetres. An exit pupil size of 2 or 3 millimetres is sufficient for viewing subjects in bright light, but if low-light performance is an issue, look for a binocular with an exit pupil size of 5-7 millimetres.
In case of 8x42 binoculars: 42/8 = 5.3 . exit pupil = 5.3 mm
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Eye Relief and adjustable Eyepieces
This describes the distance from the eyepiece to the surface of the eye where the full image can be viewed. If you wear glasses, it is best to choose a pair of binoculars with long eye relief. Adjustable eyepieces can be twisted up and down to further enhance comfortable viewing .
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F
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Fixed focus
An optical instrument lacking the ability to change focus.
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Fixed power
A binocular scope with a single magnification setting.
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H
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HD (High Definition) Glass or ED (Extra-low Dispersion) Glass
Optical glass processed to greatly reduce aberration and provide better color reproduction.
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L
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Lens
One or more pieces of optical glass with surfaces curved to converge or diverge transmitted light rays.
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Lenses
Some Olympus binoculars feature an Extra Low Dispersion (ED) glass lens element. This reduces chromatic aberration, a common problem at high magnification, to produce sharp, clear images. Other Olympus models contain an aspherical glass lens element. This also provides an extremely high degree of optical resolution, reducing distortion.
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Lens coatings
A variety of coatings can be applied to the lenses to reduce reflection and enhance light transmission. The more coatings, and the greater the number of lenses coated the better the image will be.
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M
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Magnification
Magnification refers to the apparent enlargement of the object being viewed. If you are viewing an object 1000 metres away, it will appear as if the object is only 100 metres away.
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O
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Objective lens diameter
The size of the objective (front) lens is given in millimetres and is an important measure of binocular performance. While larger lenses generally offer greater light-gathering power for a brighter view and better image detail, they do add to the size and weight of the binoculars.
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P
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Parallax
An optical illusion that causes a viewed image to apparently change position as the viewer's eye moves to either side of the eyepiece.
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Prisms
The prisms in the high-performance binoculars are coated to preserve brightness and image detail. They are ground from BaK-4, a type of optical glass that refracts very little light for great image clarity. Two different types of prism are employed. Porro-prism binoculars feature an off-set barrel design. The wide space of the objective lenses enhances the perspective by giving more depth of view and creates an impression of more three dimensional images. Because of this, the porro prisms binoculars are usually slightly bigger than roof prisms models. A roof-prism system reduces the amount of space needed by directing light through a smaller area, which also makes the binoculars lighter and more compact.
Roof-Prism Binoculars: EXWP I, WP I, RC I Porro-Prism Binoculars: EXPS I, DPS I, ZOOM PC I, PC I, DPC I
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R
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Relative brightness
Directly related to the exit pupil size, this also indicates how well binoculars will perform in low-light situations. The relative brightness index is equal to the square of the exit pupil size. A high number means better viewing in low light conditions.
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T
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Twilight factor
A unit of optical comparison calculated by multiplying magnification by objective lens diameter, and taking the square root of the product. The greater the twilight factor, the better the binocular can provide quality viewing under reduced light conditions.
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U
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UV Protection
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All OLYMPUS binoculars provide protection against harmful UV rays as they use special coatings or lenses. |
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V
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Variable power
Magnification that can be adjusted.
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W
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Wide angle
Wide angle field of view allows to spot fast moving objects.
10 x 50 DPS I, 8 x 40 DPS I, 7 x 35 DPS I have 30 % wider view.
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10 x 50 DPS I |
8 x 40 DPS I |
7 x 35 DPS I |
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Z
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Zoom
OLYMPUS offers binoculars with a zoom function that ranges from 8–16x to 10–30x magnification.
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