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Why can't someone who is myopic see reflections clearly?

  1. Mar 12, 2010 #1
    I have always wondered about this - I have moderate short-sightedness (5 diopters). If I take off my glasses and stand close enough to a mirror that I can focus sharply on the actual surface of the mirror (or the wall behind it), the reflections in the mirror of more distant objects are still just as blurry as if I were looking at those objects directly.

    Does anyone know why this is?
  2. jcsd
  3. Mar 12, 2010 #2


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    Gold Member

    If you are myopic and take off your glasses, distant objects will be blurry. Looking into a mirror does not correct your myopia, so distant (reflected) objects will still be blurry. This is why Optometrists use front-surface-silvered mirrors to extend the light paths in their examination lanes.
  4. Mar 12, 2010 #3


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    Staff: Mentor

    The images are not located in the plane of the mirror. They're located behind the mirror, at the same distance from the mirror plane as the corresponding objects (which are of course in front of the mirror).
  5. Mar 12, 2010 #4
    Ah of course! Thank you. While my studies get increasingly complicated I unfortunately seem to be forgetting the basic foundations of physics...
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