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What would make the human eye see more details?

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  1. Nov 8, 2017 #1
    First let me tell you the context: There was this recently discovered tiny sealstone depicting warriors in battle measuring only 1.4 inches across. This piece contains incredible detail that modern human eye cannot discern without a mechanical aid.

    Read more at: https://phys.org/news/2017-11-team-rare-minoan-sealstone-treasure-laden.html#jCp

    The fact that artists 3500 years ago could carve into the stone such details that modern human naked eye cannot resolve suggested to me that 3500 years ago human eye could see more details.

    I would like to ask you what part of the eye need to change to increase or decrease the resolution of the eye? Is the change need to happen in the lens? I'm not really asking if such a change in human vision is possible or not in terms of evolution in this timeframe. I would like to know the physiological change that would make the human eye see more details than it can see now.

    Thanks.
     
  2. jcsd
  3. Nov 8, 2017 #2
    I would not jump to that conclusion.
    A pantograph could be used to make a miniature copy of a line drawing - and that would not only explain the small size of the image, but also solves the problem of how to avoid errors that could not be corrected.
     
  4. Nov 8, 2017 #3
    That may be possible although I don't know if such an instrument as a pantograph was available at that time and if it could be used to draw on a stone. But what I am trying to understand is this: What needs to change in the anatomy of the eye for the eye to see as if through a loupe? Do we need a change in the lens?
     
  5. Nov 8, 2017 #4

    berkeman

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    It would most likely have to be the concentration of the Rods and Cones in the Retina:

    Wikipedia article on why Eagles have much sharper eyesight than Humans:
    https://en.wikipedia.org/wiki/Eagle_eye
     
  6. Nov 8, 2017 #5
    Ok, so it's like screen resolution. More pixel better resolution. But this question comes to mind: Why do we see a bigger image ie more details when we look through a loupe (rod and cone density stays the same but we see a sharper image)?
     
  7. Nov 8, 2017 #6

    russ_watters

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    The question is oddly circular and self answering: we see more detail on a bigger image because it is bigger and therefore covers more "pixels".
     
  8. Nov 8, 2017 #7

    OmCheeto

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    My guess is that the artist suffered from myopia (near sightedness).

    Though, not being an optometrist, nor knowing much of anything about optics, I would have to do experiments to see if my guess is correct.

    A quick google search yielded some anecdotal evidence that matches my own experience: Whenever me and my hyperopic (far sighted) friends can't see something up close, we always hand it to our myopic friend, who takes off his glasses, and makes fun of us, for not being able to see what he sees.

    From my google search:

    Are my eyes microscopes?
    June 5, 2009 8:56 AM
    Does my severe myopia give me close vision super powers?

    I am severely myopic. I don't have my eyeglass prescription in front of me, but trust me, my eyes are bad. My opthalmalogist says I'm one of the worst he's treated. [I asked another one once to quantify it for me in 20/20 terms. He said he could figure it out with a calculator, "but that reference scale is not for people like you."]

    One of the benefits (if you can call it that, and I'd like to) is that I have high visual acuity for close-up detail. I can focus clearly on very small things when they are an inch or so away from my eyeball.

    Would you like me do the experiment? It would involve creating a model of a myopic eyeball, and may take me an hour or two to complete.
    I'm sure it can also be solved mathematically, but my maths is much poorer than my eyesight, and would probably take me a week.
     
  9. Nov 8, 2017 #8

    Andy Resnick

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    Thanks for posting this, it's definitely interesting. However, it's been known for quite some time that craftsmen could perform this kind of work un-aided (typically performed by myopes, as pointed out by others here):

    https://search.proquest.com/openvie...e4d5e76f24/1?pq-origsite=gscholar&cbl=1816471
    https://link.springer.com/chapter/10.1007/978-3-642-56965-4_1
    https://link.springer.com/chapter/10.1007/978-3-540-36808-3_1
     
  10. Nov 8, 2017 #9
    From the article,
    Resolution to 0.5 mm is within the bounds of naked eye acuity. From Wikipedia,
    A magnifier comes in handy, but even my oldish eyes can still make out 1/64th inch gradations on a steel machinist's rule. 1/64th inch is about 0.4 mm.

    The oldest ground lens so far found dates about 500 years later. It produces approximately 3x magnification, and (although this artifact may have been purely decorative) magnifying aids may have existed when the 3500 year old sealstone was carved.
     
  11. Nov 8, 2017 #10

    BillTre

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    I agree with @Asymptotic that 0.5 mm is well within the acuity of humans.
    Given proper lighting, I can easily see large paramecia (~80 x 200 µm, or 0.08 x 0.2 mm).
    In this case, it is a dark background with a thin beam of tangential light from the side.

    Lighting tricks can make a lot of small details visible and would be pretty easily done by an intelligent person.
    Tangential lighting on a non-smooth surface would make shadows to show hills and valleys, just like on the moon.
     
  12. Nov 8, 2017 #11

    rbelli1

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    The article mentions 0.5mm as super small. That seems odd. I can easily discern fine human hair and that is sub 0.1mm. I can almost read the micro-writing on my passport signature line. And my eyesight is much reduced from what it used to be. I could probably read the micro-writing 10 years ago.

    Perhaps the 0.5mm is an error and the artifact has much smaller details?

    BoB
     
  13. Nov 9, 2017 #12

    BillTre

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    Below is a picture of some of the paramecia I mentioned above.
    Took a while to find it.
    The paramecia are in a beaker about 6-8 cm in diameter:
    P1000482.JPG.jpg

    I have caught individual paramecia in a pipet numerous times.
     
  14. Nov 9, 2017 #13

    Andy Resnick

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    Yes, ultramicroscopy has been around since 1905- but don't confuse 'detecting' with 'resolving'.
     
  15. Nov 9, 2017 #14

    rbelli1

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    I enlarged a drawing of the artifact and it appears that the smaller details are very approximately 0.1mm. So actually it is impressively small just mis-represented in the linked article.

    BoB
     
  16. Nov 9, 2017 #15

    OmCheeto

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    I'm wondering if everyone is looking at the same image. The highest resolution image I have run across so far was at atlasobscura:

    854f999e26b0d382c9_Seal_UC.jpg
    SHARON R. STOCKER AND JACK L. DAVIS, 2017. “THE COMBAT AGATE FROM THE GRAVE OF THE GRIFFIN WARRIOR AT PYLOS,”HESPERIA 86:583-605.
    The Department of Classics, University of Cincinnati

    There are a couple of closeups at the Univ of Cincinnati. A bit large for PF (1280 x 768). Look for the pinkish images and open them in a new window, or save them, as they render tiny on the web page: Unearthing a masterpiece
     
  17. Nov 10, 2017 #16
    Thanks for the links. The Times article image turned into unrecognizable mush when zoomed into, and even the UC image of the complete artifact doesn't have quite enough resolution, but the two photomicroscopic images do. By measuring off the computer screen with a steel rule I'm estimating tool mark width on the order of 20 to 40 μm, and this is roughly equal to the smallest intended features (hair detail, etc.). Very impressive.

    @rbelli1 hit the nail square - the article's 0.5 mm is wrong.

    sealstone_detail_plunge(annotated).jpg
     
  18. Nov 14, 2017 at 8:42 AM #17
    Looking at an object through any kind of enlarging lens, (assuming proper focus and light intensity etc) projects a SMALLER ANGULAR field (a smaller part of the total image) onto the area of the retina that previously had received the whole field. Accordingly, if you use say a 10X lens then each pixel (the light falling on one receptor) would now fall on roughly 100 receptors, with consequent improvement in your eye's ability to distinguish details. Conversely, you would only be able to see about 1/100 of the total scene at a time.

    Similarly, various types of modification to your eye's lens could increase/decrease your acuity at various distances. If you had your eye lens replaced in a cataract operation you could in principle ask for a powerful magnifying lens, though no responsible surgeon would consider doing that without some hypothetically compelling justification.

    Interestingly, some kinds of spiders, notably in the family Salticidae ( https://en.wikipedia.org/wiki/Jumping_spider#Vision ) see only a few pixels at a time, and move the tiny retina around to scan the entire scene as required, building up the image progressively. If I had read that in an SF story I would have rejected it as lousy writing!
     
  19. Nov 14, 2017 at 9:13 AM #18

    Nidum

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    It is possible that the invention of the water drop microscope predates all recorded scientific history . So easily discovered by pure chance that it could have been in use for thousands of years .

    The capabilities of a water drop microscope are completely astonishing and would certainly have allowed very finely detailed work to be done .

    I spent many happy hours as a youngster making these microscopes and minutely examining everything I could find . I remember to this day the excitement of seeing for the first time all the tiny creatures swimming in a sample of water from the local canal .

    It is also possible that just rarely pieces of natural crystal became weathered , wave washed and tumbled into poor but useable lens shapes . These would certainly have been prized curios but perhaps someone in ancient times actually realised what they could be used for .
     
  20. Nov 14, 2017 at 11:15 AM #19
    Very interesting points. I regard the crystal idea as a bit far-fetched, but those droplets, both the speculation and your youthful experience... Very interesting indeed! It might be a tragic example of vanishing technology, but hard to tell. Water droplets seldom fossilise well.
     
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