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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13
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5answers
2k views

Technical explanation of “Hitachi lensless camera”

Hitachi is bragging about a thin lensless camera. I can't find any technical information on how it works---just press releases etc.† Can anyone work backwards from the published descriptions to ...
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1answer
2k views

Type of light that is not visible to human eye but only visible to cameras?

We are trying to project a grid on a surface and are trying to find the best type of light that would be invisible to the naked eye but could be captured by a camera. The light should be uniquely ...
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1answer
313 views

SLR camera gyroscopic stabilization - limited by rotation of the earth?

In this photography stackexchange answer it is stated that the limits of performance of gyroscopic stabilization of an Olympus handheld camera is related to the rotation of the earth. I'm further ...
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2answers
149 views

Does a camera measure intensity? (picture of diffraction pattern on a wall)

I was performing a diffraction experiment with a slit of width 0.08mm (reported by the manufacturer). The conditions of my experiment allowed the Fraunhofer approximations. Thus, doing the Fourier ...
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0answers
70 views

Periscope camera with a mobile phone, how to make walls not visible on the camera/alternative solution? [closed]

I am trying to make like a "periscope" that i can use with a mobile camera. I have made a very quick prototype with two mirrors and it "works" but you can see the interior of the walls so it is not a ...
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2answers
123 views

Why does image noise happen?

Why are digital images shot with a high iso (which means the camera sensor is much more sensitive to light) so much grainer than pictures taken with a lower iso? Here is an example of the type of ...
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2answers
31k views

Green dot on photos when taking photo facing the sun

When taking a photo towards the sun, I found there is a green dot on the photo. I'm pretty sure this is caused by the sun, the camera has no problem. Question: what is the cause of this green dot? why ...
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3answers
2k views

How can IR cameras see things colder than the camera?

I’ve read that only cold-blooded animals develop IR vision to spot warm prey because a mammal would blind himself with his own heat and not be able to see anything. But I’ve seen a FLIR camera, ...
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0answers
63 views

Increase the collection effciency of lens array

In an experiment I am trying to image a phosphor surface on a camera using a 3x zoom lens. The distance of phosphor surface to lens input surface is ~100 mm. The effective focal length of the zoom ...
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0answers
85 views

Femtosecond-Camera Update

Hopefully I've posted in the correct page. Honestly, I wasn't really sure where to post... Around 2012 or so, Ramesh Raskar gave a TED talk about a femtosecond-camera produced at MIT. It has a good ...
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0answers
771 views

Simulating a noisy image: Poisson Noise Clarification

I'm currently working to simulate an image that mirrors the output of a CMOS camera we have in the lab. My images include Poisson (photon) noise as well as a gaussian (readout) noise. My issue is ...
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0answers
167 views

What is the relative importance of lens element quality in a multiple lens system? [closed]

I tried grinding a custom lens out of acrylic glass (diameter 20mm, focal length 30mm). Not very surprisingly, the result is a quite poor quality lens. I think it mostly suffers from geometry and ...
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1answer
364 views

Explain Sun Glare

Above is a picture that I took just before the sun set. Notice the prominent red blob to the left of the sun. Can anyone explain the phenomenon that creates superimposed shapes and blobs in images of ...
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1answer
520 views

Why is dark current on CCD devices pixel dependent

I'm reading about sources of noise in cameras while taking images - One of them is the dark current. That is, some electrons in the CCD device of a camera are set free due to thermal noise. Those free ...
5
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1answer
2k views

Why is TV remote's infrared wave shown by a camera as purple light, why not red or something else?

I've always seen that all the old model remotes that is used in DVD players or TVs, it emits electromagnetic waves, having wavelength somewhere in the Infrared region. But when my phone's average ...
6
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1answer
675 views

How is a CCD able to collect images in drastically different lighting conditions?

I have read the basics of how a digital camera works. As much as I have understood, the digital cameras have a device called a CCD on which photons coming from the lens are incident. The CCD then ...
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1answer
111 views

Bayer filter mosaic [closed]

Hello, How a yellow or any other color that is not rgb light, get throw the Bayer filter since only allows the RGB value to pass ?
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1answer
96 views

How do you detect the colors of a traffic light? (exam question) [closed]

I just took an exam where the question was: give three ways you can detect the colors of a traffic light given only a gray scale camera. You're allowed to use any optical devices. We learned about ...
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1answer
433 views

Which gives the most realistic pictures, Mirror, camera or their combination? [closed]

By googling, I have found several different opinions about how to take one's own facial images more realistically: Some said photos taken by cameras (smartphone's cameras, if specific) are more ...
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1answer
2k views

why shadows become dark when light intensity increases? [closed]

I observed following phenomena today: in my room with some lightings, there is a stuff toy placed in front of a wall. The ambient lighting doesn't cause any shadow on the wall currently. Scene 1: ...
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2answers
3k views

Does 'focal length' mean something different with lenses and pinhole cameras?

Sometimes different but related things have the same name by some tradition or accident, causing a lot of headache to newcomers to a field. I would like to come to clear terms with this: does the ...
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0answers
69 views

What are the physics principles behind “amphibious” camera lens windows?

Underwater camera housings have a window through which the lens looks. When the camera surfaces, a couple of things can happen, and I've seen both captured in the camera footage. In one case, water ...
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1answer
269 views

Would a camera that only takes light at 90 degrees work?

From what I understand cameras and biological eyes work in a similar fashion, they all take light in a cone and distances are perceived as the angle which the object takes up rather than it's physical ...
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1answer
46 views

What sizes are detectable from 1m using a fairly good cmos camera?

I haven't ordered a CMOS camera module yet, but I am planning to use it to detect a small object from ~1-1.5 meters. Just too be specific, say I am using the following CMOS camera (although if you ...
21
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1answer
3k views

Land proportions in NASA blue marble photographs

What is the explanation for the apparent size difference of North America in these two photos from NASA? Image source Image source
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1answer
173 views

How to obtain initial conditions to image Kerr black hole?

I'm reading Gravitational Lensing by Spinning Black Holes in Astrophysics, and in the Movie Interstellar to make a raytracer code to image Kerr black holes. The paper introduces a Fiducial Observer ...
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3answers
7k views

Why are there no stars visible in this photograph?

Pluto and Charon, photo taken by New Horizons on July 8, 2015 from a distance of 6 gigameters. It's hard for me to believe there were no stars behind the twin dwarf planets in the field of vision. I ...
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0answers
42 views

Searching for a textbook on Imaging

I'm hoping someone can recommend a book that will cover the physics involved in optical range image capture. I have a degree in physics, so I am looking for something on the technical end. To expand, ...
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1answer
711 views

How to calculate the diameter of a thin lense?

A photo produced with a single thin lense is provided. Only based on the photo I should calculate the diameter of the lense. The photo shows a ruler in the foreground and a point source of light in ...
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3answers
731 views

Why does shining a laser into an iPhone camera create these shapes?

When I shine a laser light into an iPhone 6 camera I get these weird shapes: The shapes are in no way in the background behind the laser. What causes these to appear? I know about typical lense ...
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2answers
1k views

Is it possible to calculate the dimensions of ANY object in a picture having at some known distance an object on know dimensions?

Is it possible to calculate the dimensions of ANY object in a picture having at some known distance an object on know dimensions? I'm thinking about the scenario where someone is holding a smartphone ...
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2answers
151 views

Video of light passing through water

How is this possible? https://www.youtube.com/watch?v=EtsXgODHMWk Video shows beam of light travelling through water. I was under impression that Einstein's equations showed that light speed is ...
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1answer
1k views

Size of object from its image [duplicate]

If the quality of the camera (i.e. the megapixels) (assume to be $x$) of the camera is known and an object is kept a known distance from the camera (assume to be $d$), can the actual width and length ...
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1answer
2k views

What is the visible spectrum to common mobile phone cameras? [closed]

With my iPhone I can see the IR emitter on a tv remote, which could be around 940nm, but I thought cameras generally tried to filter for the human visible spectrum (i.e. sub 700nm). I'm trying an ...
3
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1answer
556 views

Can I catch a single photon with webcam's CMOS or CCD sensors?

I thought it would be nice to capturing single photons using a webcam's sensor due to simplicity. I've read that ccd and cmos sensors have a certain percent of quantum efficiency. What about webcam'...
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1answer
1k views

How to extract depth of a pixel from an image?

I'll have a few pictures that show the same scene, but only a few things move around a little bit. Now I don't have an information about any size in real life but I'd like to extract a scaling factor ...
2
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1answer
40 views

Common CCDs and photons

Is it possible to capture single (refracted?) photons with a CCD in a typical digital camera? Are these more likely due to coatings, etc? I have minimal knowledge of physics, but am curious.
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7answers
8k views

Is there a maximum frames per second (FPS)?

Take a video camera and crank up the frames per second rate. Disregarding current technological advancements, could a camera's FPS go so fast that any two captured images be identical? Would ...
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3answers
5k views

Can I calculate the size of a real object by just looking at the picture taken by a Camera?

Can I calculate the size of a real object by just looking at the picture taken by a Camera? (I think people do that) i dont understand how? (from physics point of view)
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3answers
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What are ADU (analog-to-digital units)?

Can someone explain simply what are ADU's? I was reading this post here: http://www.qsimaging.com/blog/understanding-gain-on-a-ccd-camera/ However, I still don't quite understand this statement: "...
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1answer
267 views

Calculating distance between two objects viewed from an angle [closed]

I'm trying to determine the location of this vehicles rear bumper and the front edge of the white road marker. I can't tell if the vehicle is before, at the edge, or just ahead of the marker. The ...
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1answer
6k views

Are there any radiation emitted from the cameras? [closed]

Do modern video cameras emit any kind of radiation? If so, what range of frequencies they have? I was wondering if we can detect any radiation so any help regarding detection will also be appreciated.
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5answers
1k views

Is there a limit to the frame rate achievable with a high-speed camera?

A high-speed camera is a device used for recording fast- moving objects as a photographic image(s) onto a storage medium. A normal motion picture is filmed and played back at 24 frames per second, ...
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1answer
193 views

Increase contrast on the image taken by CCD camera

I project a pattern on a reflecting object and I capture the reflected pattern (reflected via the object) using a CCD camera. However, the reflected pattern has a very low contrast (due to volume ...
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1answer
887 views

Creating large aspheric lens profile for CNC cutting out of Acrylic plastic for huge Camera Obscura

I plan to use a CNC mill to cut a plano-convex aspheric lens from a large (300mm dia) thick(30mm) block of Acrylic (PMMA/Plexiglass). I need a focal length on the order of 800-2000mm The purpose of ...
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1answer
632 views

Help calculating field of view for ball lens I just bought

I have a 5 mm (diameter) solid ball lens that I intend to place in front of a 36mm X 24mm camera sensor (I have already made preparations for the image to be focused and for the sensor to not be ...
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2answers
407 views

How camera flash can send information

Nikon have CLS a system that allow to trigger one flash with other flash. I don't know how exactly it work from user point of view, I think that one flash (in command mode) can send information like ...
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1answer
181 views

Why does the video recorded by a falling, rotating camera seem to stabilize?

Here is a video of a GoPro falling from a plane: http://www.youtube.com/watch?v=QrxPuk0JefA Any idea what is happening when the image "stabilizes" around 0:35? I think it is because the camera's ...
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1answer
1k views

Why do people look different in a photo and in a mirror? [closed]

Edit: Why do people look different in a photo and in a mirror? What is more accurate of the two? P.S. I've edited this question and I suppose it is no longer opinion based.
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1answer
379 views

Thermographic camera vs infrared camera

AFAIK, all objects above 0K emit infrared radiation. It is an electromagnetic radiation, like visible light. I guess thermographic and infrared cameras work on the same principles, but their images ...