Tag Archives: optical magnification

Lens Technology: Aspheric lenses

‘Aspheric’ refers to a type of lens design. It is recommended for those high powered reading and magnifying eyeglasses.  There is also an aspheric design for those who are very near-sighted and wear ‘coke-bottle’ lenses in their eyeglasses. You may also see hand-held and stand magnifying lens that are aspheric in design. Continue reading Lens Technology: Aspheric lenses

Telescopes as Distance, Intermediate, and Near Low Vision Aids

Telescopes and binoculars are multi-lens devices that are used  primarily for viewing the distance, but can be adapted for use at closer distances. While most of us are familiar with the common celestial telescopes and bird-watching binoculars, the systems for use by those with low vision are miniaturized.  Continue reading Telescopes as Distance, Intermediate, and Near Low Vision Aids

Hand-held Magnifiers

Hand-held magnifiers can be found almost anywhere. These magnifiers come in many styles, sizes, and magnification powers. Commonly, they are sold as either round or rectangular clear lenses, with a handle. Other types include small pocket magnifiers and a plastic ‘card’ style.

 

Hand-held magnifiers
Hand-held magnifiers

The actual amount of magnification that you get form a hand-held magnifier is variable and dependent on how you use it. Optical lenses have an optical property called focal length. If the lens is held above the page, at the focal length, you will get the magnification indicated by the manufacturer. If you hold it closer to the page, at a distance less than the focal length, you will get less magnification.  Magnification is also dependent on whether you wear your distance glasses, your bifocals, or no glasses at all. Continue reading Hand-held Magnifiers