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How Far Can Legolas See?

How Far Can Legolas See?

There’s a famous scene in the Lord of the
Rings where the elf Legolas claims to be able to count the exact number of horsemen 5 leagues
away, and on top of that can tell that their leader is very tall. But even with the most
perfect eyes possible, would anyone be able to see that far? When we see, we’re looking at light that’s
traveled outwards from a light source, bounced off an object, passed through the lens in
the eye, and been focused into an image on the retina. Except… light isn’t a particle
traveling in perfectly straight lines – it is a wave. And therein lies the problem, both
for us, and for Legolas. Because any wave – whether water, sound or
light – that travels through a small opening will become spread out by a process known
as diffraction, which for light, essentially blurs the image. You can see this with a telephoto camera lens
where the camera aperture has been made very very small – small details in the photograph
start to become spread out, blurred, and even indistinguishable! Or, if you hold the edge
of a piece of paper in front of your eye and try to read past it, small words will become
blurry! The blur that a small point of light spreads
out to become is called an Airy disk, and the size of the Airy disk for distant tiny
objects depends only on the wavelength of light in question and the size of the opening
you’re looking through. So for visible sunlight and a human-sized pupil, diffraction limits
us to at best be able to distinguish objects that are bigger than seven one-thousandths
of a degree, for example, an object one centimeter in size a hundred meters away,. Another way
of putting this is that everything 100m away and smaller than 1cm gets blurred so that
it appears to be about 1cm in size, no matter how small it really is – subtle details smaller
than 1cm blur away. So when Legolas, who has very human-sized
pupils, looked at the riders of Rohan 24 km away, diffraction tells us that everything
smaller than 3 METERS would have been blurred to about three meters in size – perhaps he
could still count the number of horsemen, but he definitely couldn’t distinguish their
heights to within a few centimeters… Unless Legolas could see in ultraviolet. Shorter
wavelength light diffracts less, so if he could see in the extreme UV, then he’d be
able to distinguish objects 10 cm in size, almost enough to discern the height of a man. Except that pretty much any kind of air absorbs
extreme UV light – so even if he could see UV, Legolas would have been left in the dark.
Or maybe it’s just… magic.

51 comments on “How Far Can Legolas See?

  1. Wait. Putting lenses in front of the aperture obviously gets around this. I mean we can use lenses to see planets with the otherwise naked eye. So if Elf's eye corneas also acts as lens' then that changes everything.

  2. He is an elf, not human, so we cannot compare elvish physiology to that of a human. How does Superman have telescopic vision? Well, he's not human even though he has human sized pupils. Superman has his alien biology to thank for his powers and elves have a sort of built-in "magic" for their abilities.

    Oh, defraction isn't letting me see where they're taking the hobbits to. Sorry aragorn.
    the end

  4. also according to the silmarillion the world is flat as far as elves are concerned (its round for the rest) which means the horizon isnt a factor

  5. Hmm…My eyes have a slightly larger aperture than most people since I have no iris (I have aniridiat) so I wonder if I could see further…

  6. I just read lotr fellowship again and I have something that’ll blow your minds, Gandalf does not say “You shall not pass,” he says “you can not pass” which at least for me almost doesn’t sound right

  7. Let’s all remember (or learn?) that Middle Earth is not on our Earth nor in our universe. They have a different creation, different beliefs and ~magic~.
    So our human science can’t be applied to mythical creatures that probably have their own rules of how their universe works.

  8. Legolas is an elf so in every movie and book the elves are basically saying: "pfft, who needs physics. Let's all go and just prove that elves can just deny the law of gravity, sight, and what not!!!!"

  9. How would it compare to an animal with greater eye sight then Humans, like an Eagle? I know they have way better vision then us, so would it be possible with their biology?

  10. This limit of vision is perfectly correct.
    When you have a time-series of images of your target, it is possible to extract quite a bit more information out of the data.
    Especially when your target is a slowly moving object, superimposed over a static background.

  11. It's a well-known fact that when elves focus on very far objects their pupils dilate. In fact, in that particular case, Legolas eyes turned entirely black. And yes they can see a little bit in the UV but not so much so it didn't help a lot (it's mostly the pupil size).

  12. By my quick calculations, in order to see differences in size of 10cm so as to comment that one rider was much taller than the others, Legolas would need to have pupils 1.46 meters (4'9.5") in diameter! He'd basically have to be one of those giant eyeballs from Super Mario 64. Or, if he had a proportional body size, he would be 527 meters tall (assuming he was 1.80 m tall in the story).

  13. This was stupid… You didn’t even say how far he can see. This is LOTR! It’s magic and elves! Just tell us how far he can see… lol

  14. To uczucie gdy wchodzisz na YouTube by obejrzeć jeden teledysk a godzinę później oglądasz filmik jak rozmawiać z chomikami 😐

  15. In a world where a staff can be shattered by words, a kingdom can be destroyed by a melted ring, and ring wraiths can be drowned by a large wave of water horses summoned by a spoken spell, I think unnaturally keen visual acuity isn’t very far fetched…

  16. He's an ELF! See how elves can walk on top of snow when men, hobbits and dwarfs sink in? That's because human physics doesn't apply to elves.

  17. Legolas has 2 eyes, spaced about 10cm apart. Assuming humanlike anatomy, those two eyes are connected to a common visual cortex, which is able to correlate image data coming from the two eyes. Humans actually do this to some extent – you can see sharper with both eyes open, than with either one alone.

    If Legolas's visual cortex has crazy high processing power, he could use aperture synthesis techniques to see with an effective aperture of 10cm. Assuming Legolas has S-cones with a frequency response similar to us humans, he can resolve down to 11.7cm at a distance of 24km, improving to 8.8cm if he can see down to 300nm (shortest wavelength air is still transparent to).

    One thing to note, though: all of this can be used to increase angular resolution, but not depth resolution. Actually discerning how tall the riders requires knowing their distance, or alternatively, having something of known height near the riders, to compare to.

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