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Optics for longer distances

There are a number of ways to improve the distance vision.

Here we focus on aids that magnifying devices mounted in spectacle frames. See also the section aboutmonoculars/binoculars.

What kind of aid you need depends of how much magnification you need and the purpose. It can range from aid to see signs or to watch TV without trouble. Talk to your eye care professional what kind of aid is most suitable for you.

A common misconception is "the larger magnification the better", e.g. a telescopic system with 10x is automatically better than one with 5x. This might be true for one individual in a certain situation but it's not always the case. Normally, when increasing the magnification you decrease the visual field, thus making it harder to use the device. Often it's better to use as little magnification as possible. There are number of reason you should not "over magnify":

  • The more magnification, the smaller visual field. Smaller visual field might make it difficult to orientate and make it impossible to see the whole TV screen or whole sentences when reading.
  • The more magnification, the more sensitive to movements. This makes it difficult to aim the telescopic system at the target and it's really important to hold the device still.
  • The more magnification, the heavier device. More magnification demands more and/or thicker lenses.
  • In most cases it's more wise to shorten the distance and combine it with a magnifying device or optics that provide a clear image. With half the distance to an object, the retinal image is twice the size. E.g. Instead of having a 4x magnifying system for TV watching at 4 m, it's a better solution to have a 2x magnification and shorter the distance to 2 m. The retinal image is the same but better image quality and easier to use.