Questions tagged [vision]
Physical processes involved when seeing, and comparisons between with other light detection systems. Includes questions about the eye, optical nerve, brain, corrective lenses, etc.
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Why does a narrow line of falling water seem drop drop when quickly looking at it from top to the bottom?
When I was under the shower I experienced when I look quickly at a single line of water falling from one pore (from top to the bottom) it looks "drop drop" instead of continuous. Why is it ...
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Why would an object disappear when switching from monocular to binocular vision?
I have just used a compound binocular microscope which has an ‘eyepiece graticule’ (ruler in arbitrary units) in the right eyepiece lens.
If you close your left eye (or occlude the left lens), the ...
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Why do objects appear more obvious in a dark room when we indirectly look at them?
I am currently in my room and it's dark (of course not an absolute darkness as you know yourself).
When I look directly at the ceiling lamp which has been turned-off for half an hour, I can't see it. ...
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How exactly can the eye detect electromagentic waves? [duplicate]
From my understanding, EM waves are traveling disturbances in the electric and magnetic fields. They travel at the speed of light, since Maxwell's equation imply
$$\nabla^2 \mathbf{B} = \frac{1}{c^2} \...
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Why is the visible light spectrum different to a hue wheel?
The following problem has bugged me for a while, ever since I noticed it. On the Visible Spectrum Wikipedia, the following is the visible spectrum:
Now, in Photoshop, or really any colour picker, the ...
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Why specifically is looking through a telescope at the sun more dangerous than the naked eye?
At first this seems like a stupid question: "Have you never used a magnifying glass on a sunny day?!"
But any lens will only ever make the focused image as intense as the target or weaker. ...
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Is “imperfect black”, (anything other than a black hole or vacuum), actually a color?
Is “imperfect black”, (anything other than a black hole or vacuum), actually a color?
Nothing absorbs all light except for a black whole, or a vacuum which doesn’t reflect light. If we consider black ...
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How do our eyes perceive a parallel beam?
So if our eye is considered a lens, a parallel beam (sort of like collimated light from a flash light) should converge to a single point, the focal point. So does that mean our eye will see a finite ...
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How do we see the picture of an object as a whole thing in spherical mirrors?
When we see an object in a spherical mirror, the different parts of the object has different pictures which are also at different locations compared to each other.
The lights that go from the tip of ...
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Why are circular polarized 3D glasses for cinemas so cheap and working for a range of wavelengths?
Does anyone know how the filters in circular polarized 3D glasses for cinemas work (meaning how the filter on a micro-scale works, which material they use...)? Because in the lab we use of course ...
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Is it possible to design a wheel without the wagon-wheel effect?
Wagon-wheel effect is a well-known optical illusion due to the persistence of vision. It happens when the spoke of a wheel rotates to a certain position after the duration of persistent vision. ...
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Does intense, cyclically-pulsed light appear brighter than its average?
Background
The Wikipedia article on the Talbot-Plateau law mentions:
If a light flickers so rapidly that it appears as continuous, then its perceived brightness will be determined by the relative ...
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What happens when visible light transitions to invisible light?
I was just wondering what happens when you see a visible light, for example violet, and that light slowly increases/decreases until it's not visible to the human eye. Will it fade or just become ...
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Why is each of these spectacle lenses creating two distinct refraction patterns? [closed]
Each of the spectacle lenses in this image cause two separate refraction patterns:
The patterns are different between the lenses because each eye is different, obviously, but why are there two ...
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Reflection of eye floaters in a mirror
Most eye floaters are caused by age-related changes that occur as the jelly-like substance (vitreous) inside your eyes liquifies and contracts. Scattered clumps of collagen fibers form within the ...
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Insides of eyelids and light
People commonly see the insides of their eyelids and see a little amount of light and no amount of light of the insides of their eyelids depending on what environment they're in, What's the difference ...
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Strain on eyes when seeing a mirror [closed]
Suppose; The strain on my eyes when seeing an object at distance x is a.
The strain on my eyes when seeing an object at distance ...
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Why does the focus point of the eye does not burn the retina?
To see an object, its light rays have to meet on the retina in the focal point. But the focal point is a small white dot. Basically nothing would be distinguishable and the retina would burn because ...
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Is it correct to say that light makes things visible but light itself is invisible?
Why some books write light itself is invisible but makes things visible for us. I mean if a laser beam is passing just parallel to our eyes in a dust free environment we can't see it but the reason ...
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Can the human eye see the images of 300 nm light on a screen through a diffraction grating?
In my textbook there is a question as follows:
A diffraction grating with 200 lines per mm is placed between a monochromatic light source and a screen. The distance from the grating to the screen is 2....
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Finding the solid angle of a beach ball
Suppose I have a beach ball whose radius is 0.5m, and the distance between myself and the center of the beach ball is 10m. How do I go about setting up a diagram for finding the solid angle of the ...
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Horizon related question [closed]
I'm a student taking an undergrad course in physics and we were discussing light and how it works in relation to vision. This question stumped us. What altitude would you need to reach on the globe ...
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Higher the Prescription the higher the natural eye magnification [duplicate]
My optometrist told me that the magnification power of the natural lens in the eye will vary depending on the (glasses) prescription. Meaning, the higher ones prescription is, the more the eye will ...
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What specific properties of laser light make it dangerous?
What makes a laser more dangerous than a high powered single color LED for example?
Is it the fact that it's coherent light, all the photons have the same wavelength, that it can be focused to a small ...
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Why rays of light from different points don't form an image?
I'm asking a clarification about this questions:
Why does an image only form where light rays coming from a single point get reflected or refracted and converge to a common point?
I want to know if ...
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Farsightedness glasses beyond focal length
As I understand, farsightedness glasses use convex lenses to create virtual image that is farther than the object (and thus past the near point of the user). However, this only happens if the object ...
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Is color perception linear? [duplicate]
I'm learning about the trichromatic theory of color perception. Say a receptor detects a wavelength $\lambda\in\mathbb{R}$ and responds with $f(\lambda) = (r,g,b) \in \mathbb{R}^3$. This system is ...
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How do we see with glasses or contact lenses if the image formed by them occurs behind the eye?
Apologies for the poor wording of the question, I'm sure I'm gravely misunderstanding something here but not sure exactly what.
Suppose we have some point light source. We can see it because the rays ...
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Do prescription swimming goggles have a gap between the lens and the goggles?
The lens-maker's equation for a given biconvex lens assumes that the refractive index of the medium either side of the lens is the same.
But in the case of prescription swimming goggles, this wouldn't ...
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How does the human eye form an image of a certain size at a certain distance?
In looking at how geometric optics works and how an eye rebuilds an image of a certain size at a certain distance, some questions came to me:
Let's take a look at the first picture for example; the ...
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How do you simulate astigmatism and other zernike aberrations of an image?
If I have a perfectly clear image, how do I simulate what this image would look like if there had been some sort of aberrations during image capture, specified by zernike polynomials?
For example how ...
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Are human eyes interferometers?
It seems like 2 eyes is enough “wetware” to do interferometry inside brain. Can you definitely see some reason why this could not be happening, or some way to test if it does happen?
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Does any colour appear white to our eyes if its emitted power is extremely large?
let's consider an ideal monocromatic source (for instance red) and let's assume you can regulate its emitted power without compromising its spectral "finesse".
Start from 0 emitted W/sr. It ...
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Why are actual prescription lenses for myopia almost plano concave with the curvier face near the eye?
In a recent revision of the chapter on spherical aberrations in lenses, I found that the lens with minimum aberration will be the one in which the curvier side faces the incident ray.
This is shown in ...
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What do the Optometrist eyeglass prescription numbers mean?
I want to know what the numbers mean in my eye glasses prescription. The top 50 google hits give overly simplistic answers.
For example
...
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Which is the real reason for why we don't see light interference patterns?
There are many questions like mine in the web, but think I cannot fully understand it.
Let's look at this question. The first answer states that we cannot see light interference patterns because most ...
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How does RGB really work with subpixels?
first off, I’d really appreciate any help. I have googled relentlessly to try to understand this, but I’m too stupid to fathom it. Please attempt to explain this to me in plain English if you can.
I ...
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How is it possible for a human eye to see the entire reticle in a reflector sight?
Reflector sights such as used on fighter planes project an image of a reticle "focused at infinity", that is, whose rays are parallel, onto a semi transparent window. How is it possible for ...
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3D Display Technology Technique
I was randomly reminded of 3D TVs/Nintendo 3DS and was wondering about how they work without glasses as I was already familiar with 3D with glasses. Everything I found online seemed to be about using ...
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Range of accommodation in myopia
Here's what I understand about accommodation of the eye and correcting myopia with a diverging lens. (Source material)
An ideal eye can accommodate and focus any object that is farther to the eye than ...
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Why does the boundary shows different colors between black and white regions on a projector screen?
Original Question:
My friend took a picture of his screen from an angle (please see the attached picture) and found that the colors of the boundaries from white to black and ones from black to white ...
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Is it possible to get a material which yellow in normal light and doesn't reflect spectral yellow?
Imagine an object which reflects only green and red spectral colors. In normal light, it should appear yellow. But when we light up this object by spectral yellow color, it should appear dark, because ...
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Are radiance and luminance really independent of distance to observer?
Recently, I learned that apparently both radiance and luminance are independent of the distance between the light emitting object and the observer.
The reasoning was that although the radiant/...
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How we can distinguish objects separately, even if light rays from them are getting mixed up in space surrounding them?
I am a high school student and I am very confused in one thing in optics (ray optics) which I think is the most basic thing but didn't find any answer on internet, before I ask let me present one ...
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How far could you see in air?
Suppose a world that is infinitely large and flat, with an atmospheric composition and density similar to earth, how far could you see before the scattering effect of the air causes anything more ...
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Difference between Myopic Eye and Normal Eye with ray diagrams
So I have a problem where i am getting confused what happens when an object is placed in front of a myopic eye. Also I have another problem ie. why the image becomes blurry if it is formed beyond the ...
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UV & IR radiation are mostly absorbed by water. Our eyes are predominantly water. If our eyes were made of another liquid, could we see slight UV/IR?
Firstly, I'm not a physics guy. I just think it's neat, that's all.
I was reading a post on here about why water is transparent (I was more interested in why milk isn't) and saw a graph that showed ...
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How does curvature of our eye affect our perception of the world? [closed]
The front part of the eye which can allow light to enter is a bit curved, so shouldn't this cause us to see a curved distorted version of reality when it is really not there? Is there any way to ...
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Why do eyeglasses use meniscus lenses?
Any eyeglasses prescription could be filled exactly with "symmetrically-shaped" lenses.
E.g., a far-sighted person could use a symmetric biconvex lens (i.e., the normal "magnifying ...
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How to calculate Distance $D$ to object from a camera with known $H$?
I am using algorithm to draw a bounding box around object when they appear in camera as shown in attached image. The main confusion is that i consider the object closer to camera when the Distance $D$ ...
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