How does a diopter work?

by Andy on June 6, 2007

Diopter dilemma? Read on for more information on selecting the proper magnifier for you.

A diopter is a unit of measurement describing the optical power of a lens or curved mirror. When shopping for magnifiers, consider this: The diopter is equal to the reciprocal of the focal length measured in meters. For example a 5 diopter lens brings light rays to focus at 1/5 meter. Each diopter increases the size of the viewed object by 25% when the object is at its full focal length from the lens. Remember that as the lenses become stronger and magnification increases, viewing areas and focal length decrease.

An “x” usually follows the magnification number. This “x” is used to express power or the size of the object in relationship to its actual size.

How to select the magnifier for you:

  • Decide how much magnification you need. In doing so, remember that if you increase the magnification, the focal length and the viewing area will be smaller.
  • Determine which diopter you need.
  • Make sure you check the focal length and the diameter of the lens in accordance with your task

Magnifier All-Spec Industries provides all kinds of magnifiers to fit your needs.

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