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Thread: Did anyone else here discover the hand-pinhole lens when they were a kid? :D

  1. #1
    Join Date
    Dec 2004
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    UK
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    Did anyone else here discover the hand-pinhole lens when they were a kid? :D

    I became short-sighted around 13yo, and at some point I got some glasses, but I didn't want to wear them, and I discovered if I curled up my index finger, looking through the small hole that I could just about make out what was on the chalk board....one teacher friendily mocked the way I tried to hide this procedure, of trying to look like I was just leaning on my hand...what a fuss about nothing...! I started wearing glasses when I went to the upper school, and have worn them since. I think they are more cool these days, which is good for kids now.

    http://www.scienceinseconds.com/blog/Pins-Eyeballs
    Last edited by WaxRubiks; 2017-Jul-17 at 03:29 AM.
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  2. #2
    Join Date
    Jun 2009
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    The same thing is used in photography. If you want the background and foreground to both be focused, you need a small iris. A larger iris setting lets more light in, but gives the classic effect of a sharp foreground and fuzzy background.

    By using a pinhole, you are increasing the depth of field at the expense of light gathering ability.

  3. #3
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    Yup. Did exactly the same at about the same period of life.
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  4. #4
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    Didn't do it as a kid, but do it sometimes now. If my glasses are off, because I'm reading a thing in my hands (e.g. this tablet), and something comes up on the T.V. I want to read, I sometimes use this "technique".
    Measure once, cut twice. Practice makes perfect.
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  5. #5
    Join Date
    Feb 2005
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    10,924
    Leaves work better--lots of little bites on the ground

    There was a TV program The Red Hand Gang--where a pinhole was made in the side of a panel van abducted kids were using--camera obscura style--to make a movie of where they were headed using a bit of cardboard.
    Last edited by publiusr; 2017-Jul-28 at 08:05 PM.

  6. #6
    Join Date
    Jul 2017
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    cool! I never knew it, though the example with photography totally makes sense

  7. #7
    Join Date
    Dec 2004
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    14,765
    Just noticed this old thread while looking for another.

    I started getting nearsighted in sixth grade, and had to use the
    finger-aperture technique to read the blackboard when I was
    about 11-3/4 years old or so. I had an appointment for an eye
    exam after school one spring day, but forgot about it on the way
    home when I discovered lengths of new sewer culvert lying on
    the boulevard just waiting to be crawled through. As a result,
    my beautiful new Cub Scout pocket knife must have fallen out
    of my pocket and got lost, and I missed the appointment. I got
    glasses right after the end of the school year.

    I think I used the indentation on the inside of the last joint of my
    right index finger and the tips of my left thumb and index finger.

    -- Jeff, in Minneapolis
    http://www.FreeMars.org/jeff/

    "I find astronomy very interesting, but I wouldn't if I thought we
    were just going to sit here and look." -- "Van Rijn"

    "The other planets? Well, they just happen to be there, but the
    point of rockets is to explore them!" -- Kai Yeves

  8. #8
    Join Date
    Sep 2004
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    14,973
    I did exactly the same thing before I got glasses.

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