Questions tagged [camera]

A device used to record static or moving images, either digitally or on a physical medium. The images captured may be in any region of the electromagnetic spectrum such as x-ray, infrared, visible, or ultraviolet and beyond.

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870 views

How to test cutoff frequency of IR filter on camera?

Modern cell phones seems to come with IR filters on their cameras. I want to do an experiment to figure out what wavelengths these filters allow to pass and which they block. How would I go about ...
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2answers
897 views

Is there a limit to frames per second to be captured?

Today we see ~100,000 fps cameras for hyper slo-mo. Is there a physical limit for frames per second for a camera? Speed of light maybe? How?
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4answers
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Blocking an IR camera [closed]

What kind of material would be best to block an IR camera? Would Silicon work? (e.g the Silicon typically used in iPhone cases) Rather than covering the object/subject, I'm interested in fully ...
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2answers
230 views

What is “field size” when referring to perspective?

I'm trying to get my head around perspective. If you look at the animation in Wikipedia : You can see that the cube looks very distorted, then the edges go more parallel. From my understanding, the ...
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1answer
4k 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 ...
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1answer
214 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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2answers
2k views

Flashlights and Capacitors

Why capacitors are used in flashlights of cameras instead of attaching the light directly to the battery? How this leads more light?
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7answers
5k views

The rule breaker, emissivity + reflectivity = 1

If emissivity and reflectivity are inversely proportionate, why does glass have a high emissivity of around 0.95-0.97 as well as being very reflective for IR Radiation? normally it works but not with ...
11
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3answers
3k 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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0answers
68 views

Modeling the probability of a photodiode measuring photons targets at a neighbor

In current digital cameras, sensors are arrays of photodiodes which "transform" photons energy to electrons. I am aware that the probability of a photon to generate an electron is modeled by a Poisson ...
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4answers
2k views

Why do cameras have double lenses?

I was wonder why cameras the good ones have two lenses instead of one? what benfit does it carry with this fact? I have told that old cellular phones have camera with one lens and hence it blurring ...
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0answers
230 views

projective camera: back-projecting a point on the image plane into 3-space

suppose I got a projective camera model. for this model I would like to back-project a ray through a point in the image plane. I know that the equation for this is the following: $$ y(\lambda) = P^+ \...
11
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2answers
6k views

Infrared remote flashes blue light in camera

I know that if you held an infrared remote in front of a digital camera, it'll flash a blue/purplish light when you press the buttons. Why? (Image by Zombie Rider.)
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3answers
17k views

Cameras in Voyager probes

I've always wondered about the cameras in the space probes, especially in the Voyagers. 1) What kind of cameras do they have? Digital? (Electronic - what kind of sensor and megapixel count?) Analog? (...