THE COMPLETE BINOCULAR HANDBOOK While Nikon engineers of semiconductor-manufactur- FINDING THE ing equipment employ our optics to create the world’s CONTENTS PERFECT BINOCULAR most precise instrumentation. For Nikon, delivering a peerless vision is second nature, strengthened over 4 BINOCULAR OPTICS 101 ZOOM BINOCULARS the decades through constant application. At Nikon WHAT “WATERPROOF” REALLY MEANS FOR YOUR NEEDS 5 THE RELATIONSHIP BETWEEN POWER, Sport Optics, our mission is not just to meet your THE DESIGN EYE RELIEF, AND FIELD OF VIEW The old adage “the better you understand some- PORRO PRISM BINOCULARS demands, but to exceed your expectations. ROOF PRISM BINOCULARS thing—the more you’ll appreciate it” is especially true 12-14 WHERE QUALITY AND with optics. Nikon’s goal in producing this guide is to 6-11 THE NUMBERS COUNT QUANTITY COUNT not only help you understand optics, but also the EYE RELIEF/EYECUP USAGE LENS COATINGS EXIT PUPIL ABERRATIONS difference a quality optic can make in your appre- REAL FIELD OF VIEW ED GLASS AND SECONDARY SPECTRUMS ciation and intensity of every rare, special and daily APPARENT FIELD OF VIEW viewing experience. FIELD OF VIEW AT 1000 METERS 15-17 HOW TO CHOOSE FIELD FLATTENING (SUPER-WIDE) SELECTING A BINOCULAR BASED Nikon’s WX BINOCULAR UPON INTENDED APPLICATION LIGHT DELIVERY RESOLUTION 18-19 BINOCULAR OPTICS INTERPUPILLARY DISTANCE GLOSSARY DIOPTER ADJUSTMENT FOCUSING MECHANISMS INTERNAL ANTIREFLECTION OPTICS FIRST The guiding principle behind every Nikon since 1917 product has always been to engineer it from the inside out. By creating an optical system specific to the function of each product, Nikon can better match the product attri- butes specifically to the needs of the user. Exacting precision across a full spectrum of The result is what we call our “Optics First optical technologies. Design Principle,” and it applies to every optic Nikon makes. Widely acknowledged as the global leader in precision optics, Nikon’s roots go back to the development of As one of the few makers of optical glass our first binoculars in 1917. Since then, Nikon has in the world, Nikon has a unique advantage continued to build on the know-how of generations of having the knowledge and experience to of optical and precision technology experts with an specify and select the exact type of glass, enduring passion for quality and innovation. Day in and lens geometry and multicoatings needed to day out, our products are tested in the world’s most optimize the performance of any given optic. demanding environments. Using Nikon cameras and This level of performance can be seen and NIKKOR lenses, photographers around the globe cap- appreciated when putting any Nikon optic to ture moments that no one could otherwise envision. the test in real world conditions. 2 3 BINOCULAR Objective lens diameter THE DESIGN: Advantages: The objective lens diameter (the second number • Porro prisms inherently provide a better depth OPTICS 101 after magnification), combined with the quality of What Difference does it make? of field/better stereoscopic 3D images because What do the Basic lens and prism coatings, determines the amount of of the wider objective lens spacing. Numbers mean? light gathered to form an image. If you are regularly • Porro prism binoculars are generally less observing in poor light conditions, such as early dawn expensive, all other factors considered, as they or dusk, or in forested areas, you may need a larger Performance factors are less technical to manufacture to high objective lens. But large-diameter objective lenses performance levels. Nikon offers an extensive lineup of binoculars, make binoculars heavier, so 50mm is the general limit including several of the world’s most popular series for handheld use. • Porro prisms offer a bright view from total for a diverse range of applications. Each model reflection. features various technical specifications that can Disadvantages: help you in making the right selection. • Because of the dogleg barrels, Porro prism Magnification is usually considered most important, binoculars are generally bulkier, and therefore less but field of view, brightness, ease of handling (weight, convenient to pack and carry. feel, ergonomics), suitability for eyeglass wearers and overall construction should also be taken into account. Roof Prism Binoculars Magnification The Roof Prism design has a straight barrel, but not a straight light path, from the Objective lens (front) to the Magnification, represented by a numerical value, is Ocular lens (back). the relationship between a subject’s actual propor- tions and its magnified size. This is the first number The prisms inside each barrel resemble a tiny, peaked printed on all Nikon binoculars. With 7x magnification, roof – hence the name. for example, a subject 700 yards distant appears Roof prism binoculars, chosen by those who prefer as it would when viewed from 100 yards with the a slim-line design, are costly to produce because naked eye. As a rule, magnifications of 6x to 10x their very small prisms require special grinding and are recommended for handheld outdoor use. With Field of view polishing to maintain image integrity. magnification of 12x or greater, any shaking by hand The real angle of view, is the third number printed on Roof prisms also demand a relatively expensive movement is more likely to create an unstable image all Nikon binoculars. It represents the segment of a and uncomfortable viewing. coating process, much like lens coatings, to 360° circle that the binocular is designed to view. The maximize their performance. higher this number, the more of the subject you see from side to side. Phase-correction coating: This number is also used to determine if the Phase shift of light is caused by phase differences binocular can be rated as a wide-angle or wide arising from total light reflection on a roof (Dach) field-of-view instrument. surface. Called phase-correction coating, it corrects most of the optical deficiencies inherent in roof PRISMS prisms. Phase-correction coating is applied to the surface to minimize loss of resolution, ensuring Binoculars come in two prism designs: “Roof prism” high-contrast images. and “Porro prism.” The purpose of prisms, located in Advantages: each binocular barrel, is to correct the inverted and reversed images you would see in their absence. • The biggest advantage of the Roof prism design is smaller size and portability. Because Roof prism Porro Prism Binoculars binoculars have straight barrels, they can be more Porro prism binoculars are named after their prism’s compact and thin. inventor, an Italian named Ignazio Porro, and feature Disadvantages: “dogleg” or “zigzag” barrels, with the objective lenses (front) offset from the ocular (rear) lenses. • They are more costly than Porro prisms. 4 5 THE NUMBERS Real Field of View Field of View at 1000 meters Real field of view is the angle of the visible field, Field of view at 1,000 meters is the width of the COUNT: seen without moving the binoculars, measured from visible area at a distance of 1,000 meters, which can What do the Advanced the central point of the objective lens. The larger the be seen without moving the binoculars. value is, the wider the viewfield available. For example, For example, with 8x42 7.0° binoculars: Numbers and Specifications binoculars with a wider field of view are advantageous tell me? for locating fast-moving wild birds within the viewfield. Field of view at 1,000m = 2 x 1000m tan (7.0÷2) This also applies for finding small nebulas or a cluster = 122m Eye Relief/Eyecup Usage of stars in astronomical observations. Eye relief is the distance from the outer surface of the eyepiece lens to the position where the exit pupil is formed (eyepoint). Looking through binoculars from the eyepoint, you can obtain the whole field of view without vignetting. It is recommended for eyeglass wearers to use binoc- Field Flattening ulars with a longer eye relief (high eyepoint). Nikon’s field-flattener lens system technology minimiz- es curvature of field — aberrations that occur when The relationship between the dilation and contraction focusing on the center of the field of view causing the of your eyes (pupil size) and the size of the Exit Pupil periphery to go out of focus and vice versa — and determines light delivery potentials. delivers sharper, clearer images all the way to the lens periphery. • Smaller exit pupils affect brightness enormously, because the pupil of the human eye controls the amount of light entering our eye, by shrinking when Apparent Field of View light is brighter, or growing when light dims. Apparent field of view is the angle of the magnified The human eye pupil diameter ranges from about field when you look through binoculars. 2mm in bright light, to a maximum of about 7mm The larger the apparent field of view is, the wider the in total darkness. field of view you can see even at high magnifications. • For our optics-aided eyeball to take advantage With the conventional method used previously, the of available light, the exit pupil in a binocular should apparent field of view was calculated by multiplying be at least the size of our own eye’s pupil in any Exit Pupil the real field of view by the binocular magnification. given situation. If smaller, your eye will be “light (With this formula, apparent field of view wider than The exit pupil is the bright circle that can be seen starved” (not enough light reaches your eye). This 65˚ is called wide field of view.) in the center of each eyepiece when you hold the normally happens at dawn and dusk. Field Flattener Lens System binoculars about 12 inches away from your eyes with After revision, Nikon’s figures are now based on the Of course, during daylight hours, or in a well-illuminat- the objective lenses pointed toward a bright light.