Meade Instruments Corporation
Telescopes · Binoculars · Microscopes


 
How to Select the Right Binocular
 Meade Sports Optics Support

While many binocular brands look about the same, there are often important differences in performance from one manufacturer to another. The information in this section of the Meade website will allow you to choose the right binocular for your intended applications, budget, and personal preferences. Every Meade binocular, incorporates quality optical components, durable optical housings, and precision mechanical components for years of high-performance observing. It is this Meade attention to detail and intimate knowledge of optical design fabrication that is perhaps your best assurance of all.

Binoculars are available in hundreds of specifications and with a multitude of different features, but all share the same three basic components:

  • Objective Lenses: The main (objective) lenses of a binocular serve to collect light, thereby enabling the high-resolution observation of distant objects. In a quality binocular each objective lens typically is manufactured of two separate glass elements, the so-called crown and flint elements. The refractive specifications of these elements permit the objective lens to image objects free of false colors.

  • Prisms: Since the objective lenses form images that are both upsidedown and reversed left-for-right, prisms are required to invert the primary image. Most commonly, binoculars utilize either porro prisms or roof prisms for this purpose. Porro prisms give binoculars their familiar zig-zag profile, while roof prisms permit a straight-line design. Either type of prism, properly manufactured, yields excellent optical results.

  • Eyepieces: The ocular, or eyepiece, design included with a binocular has important performance implications. While the most basic function of an eyepiece is to magnify the image formed by the objective lens, in fact the eyepiece also largely determines the binocular's field of view, edge-of-field image resolution, and other characteristics listed below. Eyepieces are manufactured from two to five glass elements.

With this knowledge of the basic components of a binocular, it is now possible to understand the technical terminology that will enable selection of the right binocular for you:

Binocular Specifications: Binoculars are classified as, for example, 7 x 35mm — read "seven by thirty-five millimeters." In this case the binocular is of 7-power ("7x") and includes objective lenses of 35mm (about 1.38") diameter. Other binoculars might range from a tiny 3 x 14mm to giant battleship binoculars that are 40 x 178mm. The "WA" designation after a binocular specification, such as 7 x 35mm WA, refers to the Wide-Angle design of the binocular's eyepieces; wide-angle eyepieces can increase a binocular's visual field of view by as much as 60%.

Magnification: Magnification, or power, is perhaps the most misunderstood term of binocular optics. While higher powers can be useful, power by itself does not increase the level of observable detail; image resolution is a function of objective lens diameter, not of binocular power. Higher powers result in images that are less bright and in a binocular that is more difficult to hold steady in the user's hands. Powers of 7x to 12x are by far the most popular among regular binocular users. Binoculars with magnifications above about 16x are generally not recommended for use without a tripod.

Field of View: A binocular's field of view is measured in degrees of arc or as field-width (in feet) at 1000 yards distance. Example: The Meade 8x42mm Waterproof roof prism binocular has a field of view 367 ft. wide for an object 1000 yards distant from the observer, yielding a field of view specification of 367 ft. at 1000 yds. Other non-wide-angle binoculars have fields of view of perhaps 270 ft. at 1000 yds. Depending somewhat on the observer's intended applications, wide-angle binoculars are generally well worth the relatively modest additional cost involved.


Field of view (inner circle) for typical binocular; field of view (outer circle) for wide-angle binocular.

Binocular Coatings Lens Coatings: An uncoated optical glass lens or prism reflects about 10% of the light incident on one of its surfaces, allowing only about 90% of the light to pass through. Standard coatings of magnesium fluoride (MgF2) applied to the lens and prism surfaces reduce the level of reflected light to about 4°, and with substantially reduced ghost images of bright objects. More sophisticated multi-coatings of 7 to 15 layers further reduce reflected light and can result in total light transmission through a lens or prism of 99% or more. Some Meade models are multicoated with perhaps the most advanced multicoatings available, permitting 99+% light transmission and extremely high image contrast.
Eye Relief: Binocular users who wear eyeglasses for near- or far-sightedness may remove their glasses while observing; the binocular can fully correct for these eye defects. Observers who suffer from astigmatism, however, may need to wear their glasses to maintain sharp imaging through the binocular. In this latter case choosing a binocular with longer eye relief will enable easier binocular observing with eyeglasses.

Binocular Models
Although the nomenclature associated with binoculars varies somewhat from manufacturer-to-manufacturer, the majority of binocular manufacturers use the classifications described here:

8x21 Folding Roof Prism Binocular
Ultra-Compact and Mini Binoculars generally include objective lenses not larger than about 32mm in diameter, are of a straight-line roof prism design, and are foldable for compactness and ease of transport. Mini binoculars are small, light weight, and highly versatile in their range of applications: as a moderately-priced gift, for example, it is a rare person who will not enjoy, and find many uses for, a mini binocular. Because of their relatively small objective lenses, however, mini binoculars are not intended for high-resolution birding or other nature applications. Example: Meade 8x21mm Folding Roof Prism.
Compact Binoculars utilize porro prisms to invert the image and usually are styled to form-fit comfortably in the observer's hands; objective lenses are typically 27mm in diameter or less. As their name implies, compact binoculars, while larger than mini binoculars, are relatively small and easy to carry. For sporting events, as a gift item, or as a general-purpose travel binocular, compacts are extremely popular, because, again, for all but the most advanced applications, compacts provide a good trade-off between weight, performance, and cost. Example: Meade 10x25 Compact.
10x25 Compact Binocular
Meade 10x50 Full Size Porro Prism Binoculars
Standard Porro Prism Binoculars: Most binoculars referred to as general-purpose are standard porro prism models. The typically larger objective lens apertures, 35mm or more, of these models enable bright, high-contrast images on the entire range of viewing subjects, from sporting events, to long-range animal observation in the wild, to high-resolution study of a bird's feather structure. A moderately-priced, high-quality, standard porro prism model is a binocular for almost any observing application. Standard porro prism binoculars are available in a wide range of specifications and price points. Example: Meade 10x50 Full-Size Porro Prism.
Zoom Binoculars offer the convenience of zooming to higher or lower powers at the touch of a finger. The Meade 8-24x50 "Triple Zoom" model permits powers from 8x wide-field to 24x high-power, and with high-resolution imaging and sharp image focus at all magnifications.
8-24X50 Full-Size Zoom Binoculars
10x42 Waterproof Roof Prism Binocular
Waterproof Roof Prism Binoculars: provide high-quality binocular resolution and performance. Designed for any application where waterproof performance is desired, but not at a premium cost. Waterproof roof prism binoculars are typically of 25mm objective lens aperture or larger and include sleek, straight-line roof prism styling. Typical applications are hunting, boating, and camping. The straight-line roof prism is comfortable to hold and offer much of the optical performance of binoculars costing hundreds of dollars more. Meade Waterproof Roof Prism binoculars are also nitrogen-purged to eliminate internal fogging. Example: Meade 10X42 Waterproof Roof Prism.
Waterproof Phase-Coated Roof Prism Binoculars: provide professional-level binocular resolution and performance. Designed usually for advanced applications, such as for serious birders, expeditions, and hunting,; and incorporate the finest optical glasses, multi-coatings, phase and silver coated prisms, nitrogen purging, and multi-element eyepieces. The result is an uncompromised, bright, extremely sharp, high- resolution images throughout the field of view, and with a level of image fidelity unobtainable in lesser binoculars. Although premium-grade standard roof prism binoculars are not inexpensive, they are usually treasured for a lifetime. Example: Meade Montana 10X42 Waterproof Phase-Coated Roof Prism.
Meade Montana 10x42 Waterproof Roof Prism Binocular
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