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Magnifiers are typically characterized using a "standard" value of 0.25 m. A magnifying glass operates as the simplest form of optical instrument. It is essentially a hand-held lens that converges light to produce an enlarged, upright image that appears to stand where light doesn't actually converge, known as a 'virtual' image.
Fresnel lenses are used as simple hand-held magnifiers. They are also used to correct several visual disorders, including ocular-motility disorders such as strabismus. [68] Fresnel lenses have been used to increase the visual size of CRT displays in pocket televisions, notably the Sinclair TV80. They are also used in traffic lights.
Jewellers typically use a monocular, handheld loupe to magnify gemstones and other jewelry that they wish to inspect. [4] A 10× magnification is good to use for inspecting jewelry and hallmarks [4] and is the Gemological Institute of America's standard for grading diamond clarity.
By convention, for magnifying glasses and optical microscopes, where the size of the object is a linear dimension and the apparent size is an angle, the magnification is the ratio between the apparent (angular) size as seen in the eyepiece and the angular size of the object when placed at the conventional closest distance of distinct vision: 25 ...
Mother of pearl opera glasses and leather case. Opera glasses with handle, ca.1910. Opera glasses, also known as theater binoculars or Galilean binoculars, are compact, low-power optical magnification devices, usually used at performance events, whose name is derived from traditional use of binoculars at opera performances.
Cool frames, right? Actually, this is the "confetti top," one of dozens of magnetic clip-ons you can add to any Pair Eyewear glasses. (Photo: Pair)
[1] [2] Dome magnifiers are often used by the visually impaired. They are good for reading maps or basic text and their inherent 180° design naturally amplifies illumination from ambient side-light. They are suitable for people with tremors or impaired motor skills, because they are held in contact with the page during use. [1]
The dandy's quizzing glass of the 1790s was an article of high fashion, [1] which differs from the monocle in being held to one's eye with a handle in a fashion similar to a lorgnette, rather than being held in place by the eye socket itself.