Originally invented by Augustine Fresnel. The original Fresnel lenses were used
to magnify the lighthouse beacon light. A Fresnel lens is thinner and lighted then a ordinary convex magnifier lens.Wikipedia
After the age of about forty you will experience a problem viewing small print and tasks involving close
detail work. This eye condition is called presbyopia and a page size magnifier can help.
Field Of View: The size of the area being magnified when viewing through a magnifier lens. The higher the power
of the magnifier the smaller the field of view.
Diopter: Diopter is a measurement that is used to calculate the power of a magnifier
lens. The higher diopter will provide higher magnification. Diopter is expressed as "D"
Power: Power is how large an object or print increases as you look through a lens. Magnifier power
is expressed as "X"
Focal Length: Measurement from the center of the lens to to the object and be in focus
Focal Range: The distance
from the magnifier lens to the object
Fresnel Magnifier : A flat magnifier consisting of concentric circles.
Visual impairment (or vision impairment) is a decreased ability to see to a degree that causes problems
not fixable by usual means. Our low vision magnifiers can be of help.
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The National Federation of the Blind
National Library Service for the Blind and Physically Handicapped
National Eye Institute
American Action Fund for Blind Children & Adults
National Eye Health Education Program