The lenses tag has no wiki summary.
1
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1answer
75 views
Calculate the distance between two points from iPhone Camera
I want to calculate the distance between two objects using an iPhone camera.
Suppose I'm standing with my iPhone 10 feet away from the objects. Now, I want to calculate the distance between those ...
0
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1answer
15 views
Convergence of Light on the Retina
So, I've learned about lens ray diagrams-but the problem I'm having is that when ray diagrams are drawn for a point of an image, they converge to another point, but there are two problems that I see ...
3
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1answer
43 views
Optics, lenses and our eyes
When we view an image, is the focal point of our eye on our retina? Shouldn't that hurt?
Also, if that is how our eye works, then why don't lenses put the focal point their equivalent retina? I was ...
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1answer
28 views
Paraxial rays and marginal rays question
Paraxial rays are found to focus far away the lens whereas marginal rays focus near to the lens, why? I didn't find satisfactory answer in my academic book..
2
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1answer
86 views
Why do focal lengths affect magnification?
For compound lenses, the image formed by first lens acts as the imaginaryobject for the second lens.
In telescopes, the objective lens projects an image on its focal point which works as the object ...
0
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1answer
52 views
How to calculate beam spread of a non-point light source via an aspheric lens
I need to determine the angle, or rate of divergence of light from a single aspheric lens when I place a non-point light source (e.g. LED array) at a given distance from the lens which is less than ...
1
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2answers
93 views
How does the eye perceive a real image?
Okay, so I'm trying to grasp how the human eye will perceive the real image created for example by a convex lens. Take the upper image in this picture for example.
If you were to place a screen at ...
0
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2answers
214 views
Magnifying Glass-How does it work? [duplicate]
How does a magnifying glass work? I know it creates a virtual image of the observed object but how is it possible that humans can see the virtual image?
2
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2answers
64 views
Proof that a spherical lens is stigmatic
In geometric optics, we generally allow that, for example in the case of a convex lens, rays coming from a particular point get refracted towards another particular point on the opposite side of the ...
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0answers
164 views
Why a person with a further near point experience a larger magnification with a magnifier
Two people, Micah and Lyra, with different near points are equally
close to an object. Both inspect the object through the same magnifier
by holding the lens close to the eye. Micah's near ...
1
vote
1answer
71 views
What determines the sign of an image distance?
A lens placed at the origin with its axis pointing along the x axis
produces a real inverted image at $x = - 24 cm$ that is twice as tall as the
object.
What is the image distance?
Why ...
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0answers
33 views
Smaller Airy disk with another lens?
Is it possible to reduce the airy disk size produced by one lens with another lens placed after the previous one? For example, parallel ray incident on first lens L1 (without aberration), then there ...
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0answers
41 views
EigenMode expansion for beam propagation
I want to understand how to apply EigenMode expansion method (http://www.photond.com/files/docs/PW03_eme_paper.pdf) for beam propagation on a system of lenses.
The interface between two mediums of ...
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1answer
163 views
calculating focal length of meniscus lens
As I read about telescope, distance between objective lens and eyepiece must be equal to addition of their focal lengths.
D = F1 + F2
I used one of the eyepiece ...
4
votes
1answer
128 views
On the optics of high-resolution surveillance drones
In this youtube video (which is an except from a documentation I believe) a DARPA development for a high-resolution surveillance camera is presented. This question is regarding the optics that are ...
7
votes
3answers
123 views
Put a sensor at the focal length, behind, or in front?
My intuition tell me that at the focal length a convex lens all the light converges to a point. Following that logic, it would make sense to me that a camera chip would either need to go slightly in ...
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2answers
104 views
Ideal distance of eye from a lens
I observed that when I keep constant distance between object and lens but I move my eye, I get different magnification. When I am closer to lens I can see large image of the object. But if I go away ...
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vote
2answers
88 views
Is it possible to enlarge the output angle of a projector with outside lens?
I have a very small projector, with a small output angle (30 degree). In my current demand I want a bigger output angle(90 degree), so that I can get a bigger image within a given distance. Is it ...
3
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2answers
149 views
Effect of gas or liquid within a compound lens system
Hi my question is if a compound lens system if filled with gas or a liquid how does it affect the system when compared to the lens system being separated by air alone. Does this affect the focal power ...
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0answers
40 views
How does a lens affect the field of view in a mirror?
If one looks into a mirror, he can see a certain field of view.
If he places a convex lens that magnifies (or a concave lens that does the opposite) in front of the mirror, but so that he can still ...
1
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1answer
127 views
Optics Paradox?
Imagine we have two lens, one convex and one concave, spaced in such a way that the convex lens is before the concave lens. Now each lens has its own focus length and both are spaced such that the ...
2
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1answer
1k views
How to find focal length of a single convex lens?
I need help finding the focal length of a single convex lens. The radius of curvature is 200mm. left side is air and the glass has a index of 1.5. I search on google but there was only formulas for ...
3
votes
2answers
301 views
How to make the projected image smaller by adding one ore more lenses in front of the built in projector lense?
I have a projector that creates a large image, even if the distance to the screen is short. The device is very small, approximateley 10x10 cm if you look from above. The height is only 3 cm.
I ...
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3answers
366 views
What are these rays that appear in photograph of sun?
In many images of light emitting objects we see such rays. Why do they appear ?
What is the math behind their number and direction?
-4
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1answer
70 views
Photonics: Slab As a Lens [closed]
The question can be found here: http://gyazo.com/fc4d26cd35e6ce368ad2a8ed504f1dcc
The refractive index it references can be found here: http://gyazo.com/94fd2f3b5ea7da9226c3acd56b0024c1
I'm not ...
-3
votes
1answer
80 views
can someone describe the image which will be formed on the retina of the human who sees this image [closed]
I was trying to analyse the image which i have put here.
can someone describe the image which will be formed on the retina of the human who sees this image.
2
votes
1answer
193 views
How does a flat wedge lens work?
I've been seeing this lens in a lot of places especially microsoft:
http://www.youtube.com/watch?feature=player_detailpage&v=rJ1p5SD3sOM#t=45s
...
0
votes
1answer
118 views
How to define the required aspherical coefficients for a lens?
I would like to purchase my own aspherical lens for testing purpose. Then I need to define the required coefficients. But how?
My known requirements are f=25mm F/# 2.0 and MTF 0.5 @ 120lp/mm with a wl ...
2
votes
1answer
146 views
Curved lines in a picture (Photography)
My problem is when I take a picture (a close one) the straight edge looks a little curved. In a standard camera, like a CyberShot.
I would like to know if there is some relationship between the ...
3
votes
1answer
309 views
Compound lenses and virtual images
Ok so I have this problem where I have a system of two lenses. All I know is that the distance between the object and the first lens is 30cm, the distance between the object and the final image is ...
1
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1answer
102 views
Do eye-glasses decrease the Depth of focus?
I was reading up about Depth of Focus and wondered if glasses affect depth of focus. If yes, is it noticeable to the user?
13
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1answer
2k views
Why can you see virtual images?
In optics it is widely mentioned real images are projectable onto screens whereas virtual ones can only be seen by a person. Isn't that contradictory? I mean in order to see the virtual image it has ...
1
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3answers
517 views
What does the optical zoom in telescopes do?
How does the optical zoom works..
Does it brings the light closer to the object... Or
Does it just enlarges the picture of the object.
In other words... Suppose I have telescope with 1 light-year ...
