Organ in animals responsible for collecting visual information from the environment.

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2
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2answers
66 views

The ability to squint and focus - what is it called and is it used in optics? [duplicate]

Most people that wear glasses or contacts can squint to reduce the blurriness of their vision. How can this be explained, and has it ever been used in optics to enhance the focus or clarity of an ...
5
votes
3answers
2k views

What is the minimum optical power detectable by human eye?

If one is in complete darkness, what is the minimum optical power that the eye can "see" (let's say in 500-600 nm range). I found that for 510 nm, 90 photons can be detected (http://en.wikipedia.org/...
1
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0answers
39 views

Is light spectra different for all living bodies? [closed]

As we know that honey bees can see lots of different colours, is it possible that the light spectra is different for them? My main question is that is light spectra different for all living organisms?...
0
votes
1answer
338 views

Is near point defined for a myopic eye and far point defined for a hypermetropic eye?

I learnt about far Point of a myopic eye and near point of a hypermetropic eye. But I am confused about the above question. And if near point is defined for a myopic eye and far point defined for a ...
-1
votes
1answer
29 views

How can I get the sensitivity of some eye cone at a specific wavelength?

The following graph shows the sensitivity for eye cones and rods, but I want to know e.g. what is the red cone sensitivity for a wavelength of 500 nm? How can I find an answer for questions like this?...
0
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1answer
30 views

Does crossing your eyes to see stereoscopic images provide the same effect as unfocusing your eyes (looking into the distance)?

Not sure if this is the best place to post this. Please correct any formatting/grammatical errors I've made!
3
votes
2answers
47 views

How can you easily measure your visual range? [closed]

There are numerous ways of estimating your hearing range by generating sine waves at a certain amplitude and trying to tell when you are no able to hear a difference between on and off anymore. An ...
12
votes
1answer
491 views

Why can I turn light red or blue by holding my finger up to it?

This is a difficult phenomenon to explain. Imagine you have an opaque object partially covering a very bright light source, for example, an object held up against the sky. The left hand diagram is ...
6
votes
1answer
61 views

What happens at the point of welding iron?

What is the physics behind welding iron? It is obviously the electricity that causes the two metal parts to fuse but what is the role of the welding rod and why is it said to damage your eyes when you ...
0
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0answers
25 views

Binocular vs. monocular field of view in head-up displays

I've been reading about head-up displays in Wiki: Head-up display and understand that it works such that an image from an LCD screen (automotive) or from a cathode ray tube (aviation) is projected to ...
1
vote
1answer
33 views

What is meant by the point-source response of eye or telescope?

I have heard that a source is called unresolved if it is much smaller in angular size than the point-source response of the eye or telescope observing it. What is the meaning of point-source response ...
21
votes
5answers
8k views

Eyes open under water

Yesterday I looked underwater with my eyes open (and no goggles) and I realized I can't see anything clearly. Everything looks very, very blurry. My guess is that the eye needs direct contact with air ...
47
votes
2answers
8k views

Why do I see better under water using swimming goggles? [duplicate]

I am myopic (I don't really know if this is relevant or not) and I usually swim without contact lenses. My vision is clearly better underwater when I am using swimming goggles. I have tried to ...
3
votes
0answers
3k views

How does autorefractor work?

Autorefractors are being used by eye opticians for eye diagnosis. I searched internet for articles and wiki page as well but I wasn't satisfied. I am interested to know how do they actually work. How ...
14
votes
6answers
4k views

Optics of the eye - do we see Fourier transforms?

I've recently been learning about Fourier optics, specifically, that a thin lens can produce the Fourier transform of an object on a screen located in the focal plane. With this in mind, does the ...
0
votes
2answers
74 views

Perspective Redux (why objects seem smaller as the distance increases) [duplicate]

Last time I brought this up, the best answer featured an image that looked something like this: The argument here is that as the distance increases between the eye and the object, the angle gets ...
-1
votes
1answer
81 views

Can a high-watt laser's scattering light be damaging to the eyes? [closed]

Heyo, I recently purchased a S3 Arctic Class IV laser pointer. I bought the 3500mW. (In case that page expires, it's 445nm wavelength, 1.5mRad variant, NOHD is 279m, beam distance at 0.25 Lux 72km.) ...
0
votes
4answers
556 views

Can we see sound with our eyes? [closed]

Is there a type of sound within our visual spectrum that we can see with our eyes?
2
votes
2answers
55 views

Why don't eye lenses alter depth perception?

What it is going to do is bend the rays so that light from infinity "appears" as though it is coinciding with a person's far point. In doing so, it allows the person to see a clear image, without ...
1
vote
1answer
53 views

What happens when waves of light enter your eye? [closed]

I am doing a worksheet for my science class and I can't figure this one out
0
votes
1answer
59 views

How we are able to see red and green colored objects simultaneously if combination of red and green produces yellow?

If red and green cones in our eyes are tiggered simultaneously then our brain makes us see yellow color. But if two objects which have red and green colors respectively are placed infront of us then ...
0
votes
1answer
82 views

What happens to photons, electrons, etc [duplicate]

What happens to photons when they hit our eye? where do they end up? if they generate heat, why our eye don't get overheated? Similarly what happens to electrons when the light hits certain metals, ...
23
votes
7answers
5k views

How do we see? Where do the photons disappear?

I know that the light is reflected from a object to my eyes, but I don't understand exactly how. The photons appear from the light source and disappear in my eye! Can someone explain the phenomenon of ...
12
votes
4answers
3k views

3D glasses giving the opposite effect to that expected

I have just finished watching the new Star Wars movie (The Force Awakens), and during the end credits, text is shown upon a background of stars. Wearing the 3D glasses, I noticed that the text appears ...
1
vote
2answers
90 views

Speed and multiple images

Why an object (or something else) create multiple images of itself when it is moving fast? An earphone spinning in circle for example.
6
votes
2answers
1k views

How many frames can human eye see? [closed]

What's the limitation of our eyes? Can we differentiate 60fps from 120fps? Are new 144hz monitors just a marketing trick? Couldn't find any proper journals or studies about the matter.
3
votes
1answer
97 views

White LEDs and colour perception

I’m very interested in LED lighting and the different spread of wavelengths that are produced compared to other types (like tungsten). Given that a White LED bulb actually produces 3 different peaks ...
1
vote
3answers
2k views

How much lux does the sun emit?

I want to know how much lux the sun emits on a bright day - I don't mean when one stares directly at the sun, but rather when one walks casually outside when the sun is shinning brightly. Now the ...
0
votes
0answers
116 views

How do these 3D paintings work ? (See the images)

I know that our brain perceives two images from two eyes and combine them to see 3 dimensions and the 3D stuff uses this. But how this works and how can there be two images ? Thanks in advance :)
1
vote
0answers
102 views

Why do our eyes only pick up electromagnetic radiation which has been classified as visible light?

My understanding: Electromagnetic radiation is carried via photons - which enter our eyes and activate receptors depending on the amount of energy the photons have when hitting them. At what point do ...
13
votes
3answers
2k views

Is it possible that a person with myopia will see a blurry picture as normal? [duplicate]

I am trying to process an image in good quality to appear blurred to a normal person and good to a person suffering from myopia as seen in this source. Is it possible that a picture that is blurry ...
0
votes
1answer
45 views

Correcting Myopia with a Diverging Lens

My textbook says that a diverging lens works by rendering the object a virtual image at the myopic eye’s far point. However, wouldn’t the eye then perceive an object farther than its far point at the ...
3
votes
2answers
743 views

What is the 'resolution' of the reality in pixel terms?

What resolution should a TV screen have so that its image were so faithful as reality as if the TV were a window? Also what would happen if Physics could reproduce a 'pixel' of the size $ l_{p}^{2} $ ...
0
votes
0answers
19 views

What mega pixel are human eyes? [duplicate]

I always wonder with cameras improving still what I see from eye can almost never come close to that of camera particularly in low light. So what is the mega pixel resolution of human eyes?
0
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2answers
91 views
8
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5answers
5k views

Why can't we see infrared light?

While explaining to my nephew about the physics of light, I told him we cannot see infrared color, and he kicked back with a very simple question: why can't we see it? I could not tell him. Is the ...
8
votes
3answers
11k views

Is wearing 3D glasses from the cinema as sunglasses hurtful to the eyes?

I heard a few times that using them as sunglasses is hurting the eye since UV light is not filtered, but the pupil is wider than it would be w/o wearing them because the visible light is dimmed. I ...
2
votes
3answers
719 views

Why doesn't the Sun appear green to our eyes?

The spectrum of the Sun as seen at sea level can be seen at https://commons.wikimedia.org/wiki/File:Solar_Spectrum.png so we can see that wavelengths around green to yellow are the ones that are the ...
1
vote
4answers
4k views

If we had three eyes, would our visual perspective be fourth dimensional?

If one covers up one eye, then he loses depth perception (two dimensional perspective). When we uncover that eye, we can now see depth (three dimensional perspective). My question is if we had four ...
0
votes
2answers
88 views

What would/does it look like if your eyes see an object from 2 different times in the same moment?

I don't know pretty much about physics and I'm sorry if there is something I should know that simply makes it clear this couldn't happen. But I asked this myself now already several times and decided ...
2
votes
2answers
180 views

Do our eyes act as observers at the quantum level? [duplicate]

This is a very high level question. I was just thinking about the idea than in quantum physics, the act of observing has a "strange" effect on some properties (e.g. double slit). If I'm staring at a ...
1
vote
0answers
91 views

What is the minimal size of the spec of dust I can see with naked eye?

When sun directly shines thru the window - I can see small specs of dusts in the air. All specs have different sizes. Assuming direct sun luminosity is 100kLux, spec is a perfect sphere, reflection ...
2
votes
0answers
43 views

Can a person with bad vision see a blurry picture clearly? [duplicate]

I was just thinking to myself how weird it must be to have bad vision. Then I thought, I wonder if you could print a picture that would appear clear to someone with bad vision. That seemed unlikely to ...
30
votes
9answers
4k views

Is it possible to blur an image in such way that a person with sight problems could see it sharp?

If someone has short or long sight, is it possible to tune image on a computer monitor in such way, that a person could see it sharp as if they were wearing glasses? If not, will 3d monitor make it ...
-2
votes
2answers
2k views

Why we can't see light emitted from TV remote while a camera can?

If we try to see light emitted from tv remote we can see this. while if we try same in camera we are able to see this. Why?
36
votes
4answers
5k views

Why does a moving fan seem transparent?

We all know when fan starts moving faster, we cannot see its blades. Why is this? First I assumed persistence of vision may be the reason. But that can happen with blade also right? Image of blade ...
1
vote
1answer
1k views

Why do we see brown light?

While researching about lasers (it's my hobby), it suddenly hit me: there are lasers for every color of the visible spectrum, but there are no brown lasers. Brown isn't even on the rainbow. How is it ...
62
votes
11answers
23k views

Is it possible that there is a color our human eye can't see?

Is it possible that there's a color that our eye couldn't see? Like all of us are color blind to it. If there is, is it possible to detect/identify it?
0
votes
0answers
193 views

Is the human eye diffraction limited, or is there another limiting factor?

I know that most problems involving the human eye in my undergrad physics text book tell the student to treat the human eye as a diffraction limited system (ie to assume the only factor limiting human ...
11
votes
4answers
5k views

Do eyeballs exhibit chromatic aberration?

Fairly straightforward question. If not, why not? I suspect that if they do, it is not perceived due to the regions of highest dispersion being in one's region of lowest visual acuity.