A monocular is an optical instrument that is designed for viewing an object with a single eye. The counterpart to this are the binoculars . The term is derived from the adjective monocular (from the Greek monos for "a" and Latin oculus for "eye"; see monocle ), which refers to monocular vision (seeing with only one eye).
Overview of monocular optical instruments
The monoculars include both optical instruments that are used for remote observation and those that are used for close observation. The terrestrial and astronomical telescopes and reflector telescopes , theodolites , one-eyed binoculars ("monoculars" in the narrower sense) and spotting scopes are used for remote observation . Traditional light microscopes with monocular viewing are used for close-up observation . In addition, the principle of monocular observation and measurement is used in numerous special instruments, e.g. B. in refractometers .
Manufacture and use
Soon after the Porro prisms were patented (1854), monocular binoculars (“monoculars” in the narrower sense) were developed, but were not widely used because they were in competition with binocular binoculars from around 1900. After that they were offered as “half” 6 × 30 and 8 × 30 binoculars because their production only cost around 30 to 50% of the same binocular binoculars. After a phase of rather lower production and demand, they have been reinforced again since the 1990s and built in numerous variants so that they can be used as space-, weight- and money-saving binoculars as well as in special devices. A disadvantage, however, is the less relaxed view, which can lead to rapid fatigue (compare possible countermeasures in the section "Monocular vision"). Due to their construction, they are also mostly sensitive to lateral light and have a rather narrow field of view. They are therefore most suitable for situations where you only have to look briefly at a stationary target (e.g. to locate or recognize a distant object, when playing golf, when surveying or for laser distance measurement).
Optical parameters and structure of the optical system
For the optical properties and parameters, such as magnification, brightness, distance setting, types of glass and coating, as well as for the structure of the various optical systems, the same applies as for binocular binoculars (binoculars), so that reference is made to the information provided there (cf. . binoculars # Operating principle, characteristics and quality characteristics ).
Today's construction methods and coatings for optics differ greatly, which also results in considerable differences in use and price. Some manufacturers build them in the Porro system (e.g. Minox in the Macroscope MS 8 × 25), but most of them use the straight roof edge system. The most common glass sizes are 3 × 12 to 10 × 25 or 6 × 30. The field of view of the current models varies between around 96 m (e.g. Tasco 10 × 25 Camo) and 200 m (e.g. Zeiss 3 × 12) at a distance of 1000 m. The close focus is often around 0.6 to 4 m, but occasionally also 0.35 m (Minox Macroscope) or even 0.2 m (Zeiss 3 × 12). Sometimes the depth of field is only slightly developed, which requires very precise focusing (Minox Macroscope), sometimes the devices are also set as fixed focus systems that neither require nor enable focusing ( Eschenbach 4 × 13, sharp from 2 m). In the latter case, the accommodation ability of the eye of the observing person largely determines how sharply they can see through the device. Some of the devices are optically designed in such a way that they can be used as a magnifying glass when looking through them upside down (with a very small section and a shallow depth of field ).
Some devices are now also offered with a zoom (e.g. Luger MZ 5–15 × 17).
The weight of all these small optical instruments is between approx. 45 g (Zeiss 4 × 12 T) and approx. 212 g (Luger Monocular MD 6 × 30).
Monoculars with a higher magnification are also available, which represent a transition into the field of spotting scopes. While some of them can still be held hands-free as a trial (e.g. Leupold Golden Ring 10–20 × 40 mm Compact with straight-ahead view, 447), this is fundamentally no longer possible with others (e.g. Vixen Handy Eye 15 × 50 with angled view, 250 g weight). You need at least a one-legged, better a three-legged tripod or some other solid surface (if necessary, a car roof).
Laser rangefinders, which are used for various observations and measurements on the mainland (e.g. hunting, golf, architectural measurements) or on the water, are also often based in the optical part on the principle of the monocular and often magnify by 6-8 -subject. Many night vision devices are also based on the principle of monoculars, but are mostly designed for only a slight magnification of 2 to 3 times.
Monocular perception and vision
The more general meaning of monocular vision and perception is relevant on the one hand in ophthalmology , on the other hand in numerous technical and scientific works. Monocular vision is the predominant visual observation technique, especially on instruments such as reading microscopes and terrestrial and astronomical telescopes . However, prolonged one-eyed observation can cause eye fatigue and general exhaustion. To prevent this, some relaxation rules can be observed, for example:
- Keeping the "uninvolved" eye open (for example when measuring with a theodolite (angle measuring instrument with a telescopic sight) or when using a light microscope )
- Wearing an eye patch (often recommended for amateur astronomers and sport shooters )
- frequent, conscious blinking , light massaging of the face, palming .