Binoculars and Opera Glasses

Binocular Diagram

Eschenbach binoculars are available in a variety of models and many have won design and styling awards.

When choosing binoculars or opera glasses, it’s best to begin by identifying the exact purpose for its use (e.g., watching sports events, for use on nature walks, for hunting, for vacations, while sailing, or at the theatre, concerts, opera, plays, etc). For example, for sailing, you would want binoculars that are waterproof.

Important Binocular Features and Concepts

Prism Types


  • Porro prisms are wider than comparable roof prism binoculars, but not as long. Porro prism binoculars offer a slightly more 3D image at short distances. Roof prism binoculars are very compact and very slim in form. A higher level of precision engineering is required for roof prism binoculars than for the Porro prism type binocular.
  • Bk-7 prisms are boron crown glass prism, which is the standard for a quality image.
  • BaK-4 prisms are carefully machined high-performance prisms of barium crown glass and provide even better resolution of details and a brighter image with high color fidelity.
  • BinocularsSK15 prisms are manufactured from extremely high quality SK15 glass. These prisms allow the minimization of undesired internal reflections and provide pin sharp images with optimum contrast.


The magnification value gives the apparent magnification that the lens of the binocular or opera glass produces. For example: 8x magnification means that an object which is actually at a distance of 800 meters [2,624.6 feet] appears to the viewer to be at a distance of 100 meters [or 328 feet].



When considering lens criterion for binoculars or opera glasses, it’s important to know that the lens diameter is given in millimeters or mm. The bigger the lens is the more light it gathers and the brighter the image.

Field of View


This value specifies the width of the terrain that you can see through the binoculars at a distance of 1,000 meters [or 3,280.8 feet]. The greater the field of view, the easier it is to view landscapes or moving objects. This feature would prove beneficial at sports events or when viewing animals. Binoculars with a Ww (wide angle) designation have a particularly large field of view.

Exit Pupil/Brightness Index/Twilight Factor

These are index values which result from the ratio of magnification and lens diameter. An exit pupil between 2 and 3 mm is sufficient for use in daylight. Binoculars with an exit pupil of 6-7 mm should be chosen for difficult light conditions.

Minimum Focus

This number gives the shortest distance at which objects can be seen sharply and without distortion.Schraeg This value is important to know if you are buying binoculars for use in museums or similar outings where you will be viewing objects at short distances.

Internal Focusing

Focusing means adjusting the sharpness of an image. Only the lenses inside the binoculars are moved during internal focusing. A ‘closed’ system is preferred in order to avoid drawing in dust, air or humidity.

All-Weather / Waterproof

This term refers to a system of water repellent features on the casing and the moveable components in the binocular which makes it resistant to pressured water.Act

Nitrogen Filled

Eschenbach binoculars are nitrogen (N2) filled for heavy duty all-weather applications. This prevents internal optical components from misting up in situations of severe temperature changes.

Anti-Reflection Coating

  • Eschenbach binoculars have fully coated optics, which means that all air/lens interfaces have an extremely thin anti-reflection coating to optimize the ‘light movement’ through the binoculars when it reaches the eye. Coatings with magnesium fluoride are standard. This type of coating is also known as blue coating.
  • On some binoculars, this can be combined with multi-coating on one side of the lens and the eyepiece to provide ‘combi-coating’ for even better light transmission. For the highest vision requirements, multi-coating is always used on all lens faces.
  • Eschenbach also employs a ‘nature-bright’ coating on some of its binocular models [Farlux and Regatta models] to ensure true-to-life, completely color accurate images.

View our binocular and opera glasses collection and purchase the binocular or opera glasses that best suits your needs!