What is the difference between opera glasses & binoculars?

What is the difference between ‘opera glasses’ and ‘binoculars’?  It depends on how close you look.  Opera glasses are binoculars—but very specialized binoculars.  This brief synopsis describes what sets opera glasses (aka: opera binoculars, theatre binoculars, theatre glasses) apart from the more-common binoculars.

Purpose of opera glasses: Opera glasses are designed specifically to be used in indoor settings and viewing theatrical performances, such as opera, ballet, musical theatre, and musical performances. Fine arts patrons use the glasses to see the fine details and facial expressions often missed by the audience.  Opera glasses have also been used as a status symbol throughout the ages.	Purpose of regular binoculars: ‘Regular’ binoculars can be used for just about anything.  Typical uses are outdoor related, such as camping, bird watching, hunting, viewing sporting events and observing nature.
Magnification of opera glasses: The dominant magnification is 3x.  Some have a magnification of 4x.  5x is not common. Why such low magnification?  3x magnification is preferred because it allows the viewer to see a wider view of the stage—close enough to see the details, but not so close as to miss the big picture. As magnification increases, field of view decreases.  For example, at 1000 yards, 3x opera glasses give a field of view is 385 ft.  4x opera glasses show 228 ft and 8x show only 126 ft.	Magnification of regular binoculars: Typical binoculars have magnification ranging from 8x to 12+.  Magnification varies depending on their intended use.  Zoom binoculars allow you to zoom from weaker to stronger magnification. Higher magnifications show much more detail, yet with a smaller field of view and a less-bright image.  One drawback to higher magnification is the shakiness in the viewed image.
Opera glasses design: Opera glasses are designed to be small—small enough to fit easily into a pocket or purse. Opera glasses have roof prisms—meaning the prisms are lined up in a single barrel for each eye.  This is what gives them the chic, streamlined look and compact size. Opera glasses have a single focus wheel to focus both eyes simultaneously. Opera glasses are designed to give a brighter image then regular binoculars.  This is because the objective lens diameter (the lens pointed away) is significantly greater than the eyepiece lens, usually relatively small.  This brighter image is desirable in a darkened theatre. Opera glasses have multiple optional attachments & styles.	Regular binocular design: Non-opera binoculars are much larger because of the larger lenses and prisms.  Weight and size are not usually as much as a concern. Binoculars can be either Roof design (prisms aligned in a straight housing) or Porro design (prisms are offset), which are larger.  Binoculars can be compact and 8x are often nearly as small as opera glasses.  Most are usually much larger and heavier than opera binoculars. Regular binoculars often have a focus diopter ring for the right eye and a central focus wheel on the center hinge to adjust focus for both eyes.  The purpose of the two focus mechanisms is to adjust for astigmatism and differences between each eye. Because they are not designed for use in theatres, regular binoculars are usually not the best choice in a dark theatre.
Opera glasses styles / attachments: Opera glasses can be purchased in the following styles: ·       Traditional – This is the original, basic model and the least expensive. ·         Lorgnette handle – The lorgnette handle allows you to hold the opera glasses to your eyes while comfortably resting your elbow at your side or on the arm rest.  It telescopes to varying lengths and conveniently folds over top of the glasses when the show is over. ·         Chain – The chain allows you to hang the glasses around your neck when you are not using them.  This is very useful and safe, letting you move around without worrying about losing the glasses or dropping them on the floor. ·         LED light – The light is a small, narrowly-focused red light located on the center hinge.  Its purpose is to let you read the playbill or program during the performance.	Regular binocular attachments: Regular binoculars are likely to come with a strap to hang around your neck.  For extensive field viewing, nice over-the-shoulder straps give security and convenience of keeping the binoculars in a handy, accessible position.
Opera glasses prices: Opera glasses are very affordable, considering their high quality.  Normal retail prices range from $50-200.	Binoculars prices: Binocular prices vary widely, ranging from under $50 for compact glasses to over $3,000 for the highest-quality.   Expect to pay around $150-200 for your common camping binoculars.

A great pair of binoculars, whether specialized for theatre or outdoor use, can really enhance your experience and make it more vivid and memorable.