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Doth my eyes deceive me??

  • 23-09-2019 10:42pm
    #1
    LazyClouds
    Registered Users Posts: 524 ✭✭✭


    I was considering putting this in the eyeglasses etc forum but I think it's a physics question...

    I'm short sighted so everything further than a foot away from my face is blurry. I got out of the shower today and noticed my reflection on a magnifying mirror on the other side of the room (at least 4 feet away from me). I wasn't wearing any glasses but I could see my face in the mirror perfectly clearly (albeit upside-down)

    Can someone explain this to me? I understand what magnifying means but I just don't understand how my eyes were capable of seeing that far away. It just seems really strange to me. What's actually happening here?
    Tagged:


Comments

  • #2
    Bit cynical
    Registered Users Posts: 2,338 ✭✭✭Bit cynical


    I think what is happening is similar to a reflecting telescope. Points on a comparatively distant object (your face) relative to the mirror are being inverted and focussed on to nearer points in front of you.

    The difference is that in a telescope you would also have an eyepiece that, like a magnifying glass, would allow viewers to focus on this near image. You, being short sighted however, do not need this extra lens as your eye is already adapted to viewing nearby images so you see this close up inverted image in focus.


  • #3
    Biodegradable
    Banned (with Prison Access) Posts: 350 ✭✭Biodegradable


    I'm kinda a Joe Jackson fan too.


  • #4
    Iderown
    Registered Users Posts: 233 ✭✭Iderown


    LazyClouds - do a quick experiment some time.

    Without your glases, or contact lenses, stand in front of your concave mirror as you did before. Find the image of your face which is in focus. Then move back a small distance from the mirror. I bet that the image goes out of focus!


    I'm myself short-sighted. I often call short-sight having my very own built-in microscope.


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