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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17 views

Relating exposure time of a camera to number of photoelectrons

How can we relate the exposure time of a camera to the number of photoelectrons created on the detector? We know the power and the wavelength of light hitting on the camera, quantum efficiency of the ...
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Can a curtain create a focused image on an opposite wall?

This video* (linked at the correct time of 0:26 sec) shows a scene inside a room of a home. Apparently projected on the wall is an imperfect but recognizable image of the outside street scene. The ...
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Type of camera that is used in a double slit experiment [closed]

I need to know the type of camera that is used in a double slit experiment. Both with photons, and that with electrons? Can someone please answer. The type of camera that is used for observation. Is ...
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How do single-pixel cameras work?

To obtain images using a single-pixel camera we need a Digital Micromirror Device (DMD) because single-pixel cameras only possess a single detector (article). From my understanding, a single-pixel ...
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If image formed by a plane mirror is virtual, then how are we able to capture that in a camera?

What I have learnt in school is that, we are able to see images behind a mirror(virtual image) because our brain assumes that the diverging rays that our eyes see, are coming from a point behind the ...
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24 views

Specular Reflection of IR Light

I have started to use thermal imaging cameras more and more and realized that I can see the reflection of my self bouncing off of a glass window through the IR camera. When viewing it on my monitor, I ...
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32 views

Pinhole camera as a device to develope photos of distant stars? [closed]

Could a transparent slab coated with photosensitive film be placed inside a pinhole camera nearly paralel to the path of the light emitted by a source of light(star) to produce a picture wich due to ...
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51 views

Vision: eyes vs cameras

I think this is related to physics, and light waves. Is there some materials that can be seen by human eyes and can't be seen by cameras? (Imagine a special writing) Is that even possible therotically?...
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Why hyperbolic shapes of colour distortion in this image? [duplicate]

I took a photo of my computer screen through my mobile phone camera. Why are these color distortions in hyperbolic shape?
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140 views

Limits of zooming in (for camera/telescope)

What limits the ability of a camera/telescope to zoom in on distant objects? The question is twofold: What zoom really is? Firstly, I would like to gain clear understanding of what we mean by zoom ...
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What shape are digital camera lenses?

I originally thought that digital camera lenses are the same shape as a magnifying glass but I saw that lenses like that are meant for our eye which has a curved detection surface and if a camera used ...
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Estimating the focus plane of camera via thin lens equation [closed]

I have a camera that outputs a JSON file for every image taken. In the JSON file, I can find camera-specific and also the photo-specific acquisition parameters used. The issue is I wish to estimate ...
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Understanding atmospheric transmission's effect on IR camera [closed]

I'm using an IR camera to view a person at 1 meter, and then 5 meters. When I view them at 5 meters the max temperature I see for them drops by about 1 degree Fahrenheit. I assume this is because the ...
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153 views

Difference Between Angular Resolution and Spatial Resolution of optical device (Camera)

As per wikipedia angular resolution is the ability of device to capture minute details of an object and is the same definition in case of spatial resolution. Whats the difference Between Angular ...
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Programming integral to go from Image Scene to Light Field

below is the integral I am ultimately trying to program in python 3. To describe the integral, it takes an image scene's photon emission E(s,t,z) and converts it to 4D light field data that a camera ...
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Are confocal microscopy and f-number based on the same principles?

We use a small pinhole in confocal microscopy to block out-of-focus rays, much like having a high f-number (small aperture) in a normal camera. Are the two related? And does one ever tune the pinhole ...
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Why does a pinhole create an image of the Sun?

When I was a kid I happened to encounter a solar eclipse. I was taught that I should not look at the Sun directly when it is undergoing an eclipse, but I was extremely curious to see it. Somebody ...
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49 views

Flicking a ruler (Camera optics)

A while ago I found this post on reddit which showed a ruler vibrating differently depending on the light: https://www.reddit.com/r/blackmagicfuckery/comments/ccymjq/...
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311 views

What is the white spot in the sky in this phone-camera photograph?

Consider the image below, taken with a phone camera. There is a white spot near to the Sun, which is dependent on the orientation of the phone. I know it is not a planet nor some sort of star but it ...
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56 views

Astigmatism and focusing a camera

A thought experiment: assume I have poor eyesight, but using a viewfinder or an LCD screen I was able to focus a camera on an object or landscape with what seemed to me perfect clarity. I took the ...
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28 views

Finding exposure time of a satellite camera

Note: I am not sure if this is the correct stack for this question I'm working on a cubesat project, specifically on the camera payload. I've been tasked to find the exposure time of a VIIRS ...
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1answer
91 views

What are the objects that are like a crescent and blue sphere? (while taking shots of a solar eclipse)

This is the picture I have took while the solar eclipse. What are the objects that are like a crescent and blue sphere? I know that such (rays) appear whenever we photograph the Sun but what is the ...
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38 views

Why is the room converted into a camera?

Our physics teacher turns off the lights and has a tiny square of light open through the window, everything else being completely dark. There is a parking lot outside of our class and she is holding a ...
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65 views

Basics of camera calibration

I tried to find some useful explanation about camera calibration and stereo camera setup in the web but was completely overwhelmed by the hairiness of the content: but seriously though, does it have ...
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31 views

The change of focal distance as a result of adding a substance [closed]

I have a given focal distance between lens and an image sensor (in air). Now I add a protective glass with a known refractive index and width between the lens and the sensor. How can I calculate the ...
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40 views

Unique optical map of a uniform metal object

Given a metal object (let us say a perfect planner uniform surface) that has been exposed to external environment factors such as sun, wind, rain and others for couple of years. This object has been ...
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68 views

Calculate dark noise in CCD given a pixel's counts for two exposures

Suppose I took two pictures with the same CCD camera in totally dark room. The first picture was exposed for 1 microsecond, and the pixel given was 20 scales of grey. The second picture was exposed ...
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How I can add lenses stacked on front of iphone camera to increase magnifying power?

How we can stack different lenses to increase magnifiying power of a smartphone camera? Is there any way to test if stacked lenses will focus light on image sensor of smartphone exactly right before ...
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CalTech has actually filmed light crossing a space of 1 mm of space. How?

In the video https://www.youtube.com/watch?v=7Ys_yKGNFRQ, CalTech has a camera capable of filming the picoseconds it takes for light to travel 1mm in distance. It can do 10 Trillion frames per second....
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A Cheap Way for Seeing 1000nm to 1600nm Light

I have started a project in infrared where the spectrum covers 1000nm to 1600nm. A silicon based image sensors can see up to about 1000nm, while an iPhone attached FLIR camera can see from 8 – 14 µm, ...
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173 views

Determining lens and sensor distance for narrow focus

I have the following items: a round target object, approx. 6mm in diameter a lens, focal length 20mm, F/2.8 a camera sensor, optical size 1/4" (note: I know this camera has a fixed-at-infinity lens, ...
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49 views

Would Camera Obscura work in low light conditions?

If I were to attempt to create a camera obscura affect in order to capture an image of the stars, or an aurora, would I still be able to get a decent one despite the relatively lower lighting ...
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52 views

Unable to get interference from milk using Time domain OCT (Michelson Morley interferometer) approach

I was able to construct time domain Optical coherence tomography based on Michelson Morley interferometer using a LED. While testing the interferometer, I used glass slide, layers of scotch tape. I ...
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How to add protective enclosure around exposed thermal camera

First off, let me state that I'm not entirely sure this is the right forum for this question. This was the only section I found multiple questions pertaining to thermal imaging, however, so I thought ...
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How to calculate minimum optical power required from datasheet of camera sensor?

How can I determine from the datasheet of a camera sensor the minimum optical power required to see a spot on the image? I have 2 lasers with a diameter of 0.35 mm with respectively a power of 12nW/...
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How can I correct a projector's magnification with a simple lens?

I am struggling with a real-life optics problem. At work, I have a projector that makes an image too big for the screen. I think I can reduce the image to the required size by mounting a simple lens ...
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1answer
32 views

How loud does a sound need to be to make pressure waves detectable by a camera?

I've seen Veritasium's video that describes how sound can be picked up by a camera by observing small movements of objects sensitive to pressure changes (bag of chips, aluminium foil, paper...). That ...
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573 views

How does the diaphragm in a camera work?

I think I am quite good at math and understand basic geometry, but I have problems understanding the function of a diaphragm in cameras. Let's say a camera is in a specific state. It captures the ...
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168 views

How can I focus an optical device at infinity, inside a room with limited space?

I have a custom coupled camera/spectrograph imaging system that I need to focus at infinity for a microscope setup. I can't move the device outside, where I would be able to use some distant object to ...
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54 views

Optics of an all-sky camera

I'm curious about the optics of an all sky camera like this one or this one. My suspicion is that the sensor has an inherently wide field of view - the former has a lens that's 1.55, which doesn't ...
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Calculating required amount of lumen for camera sensor satuation

I am stuck on this problem at work - I hope some of you can help me further. I work with underwater vision and am trying to find way or methodology to get a somewhat estimate of the required light ...
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Are These Guitar Strings Demonstrating Subharmonics?

This video has a fair few instances where there is an exaggerated wiggling of the guitar strings. I rationalise this by saying its a similar effect to rotoscoping, like where wheels appear to spin ...
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Strange optical distortion in a video recorded from an airplane window

I recorded this video from an airplane window while it was decreasing its elevation. What is the explanation for this optical distortion? This distortion appeared only in a certain range of elevation. ...
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Photomulitplyer Tubes and NaI(TI) crystals in Gamma Camera, Energy and spatial resolution

I am trying to understand how the PM tubes and NaI(TI) crystals are used for the energy and spatial resolution. I understand the principle behind how the crystals and PMT work, but very confused to ...
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21 views

Can a controlled lighting environment be a substitute for bandpass light filters?

Could illuminating a subject with different LEDs be used instead of bandpass filters? I am experimenting with capturing surface reflectance using a monochrome camera. The traditional approach to ...
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51 views

Calculating light level radiating back to camera from rough surface

Problem statement: I have an imaging sensor (“camera”) that has a minimal response specified at 1000 lux. This camera is set up to resolve a rough surface at 1 meter distance. Alongside the camera is ...
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42 views

Solving for $x$ and $y$ image coordinate given a 3D point

I have a 3D point, $(X, Y ,Z)$ and I want to know where it's imaged, $(u, v)$. I'm assuming a pinhole camera model with no lens distortion. I have the distance from the pinhole to the object ($z$), as ...
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How do I calculate the geometric dimensions of the following objects, given the image co-ordinates, and camera information?

I've zero knowledge in optics, but I've to estimate the geometric dimensions of objects from the values of the number of pixels and the camera information given here: https://www.raspberrypi.org/...
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Why doesn't projected image fill all my camera view?

so lets say i take a small lcd, and stick a lens in front of it. a magnified image will be projected on a wall. now lets remove this wall and stick a camera a little behind where the image is formed (...
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Why is the focal length of a camera inextricably linked to a different perspective?

The human eye can focus on different distances without ever changing the perspective. Why is the change of focal length in a camera, on the other hand, always linked to a change in perspective? Is the ...