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.
187 questions
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14 views
Thermographic Analysis Best Practices
I have recently been assigned to conduct thermographic analysis on composite materials, and as I am new to this field, I would appreciate guidance on experimental best practices. My current setup ...
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8 votes
3 answers
939 views
Why don't objects 'invert' when viewed through a very small aperture? [duplicate]
We have seen in textbooks that, in a pinhole camera, light rays intersect at the aperture and then 'invert' inside the camera. But when I tried to replicate this by viewing objects through tiny holes ...
16 votes
6 answers
4k views
Why doesn't a pinhole camera work with a large hole?
All the explanations in the internet about pinhole cameras show two rays from outside passing through a small hole and produce an inverted image inside. Why doesn't it work with a big hole? Or ...
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5 votes
2 answers
403 views
How exactly does a camera measure the electromagnetic field?
I know that a camera does not directly measure the immediate value of the electromagnetic field's vector, but rather the average value of a derived quantity (a statistic of the EM field). Perhaps this ...
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1 vote
2 answers
165 views
I am making a room sized camera obscura but I want to capture a specific view not directly in front of the windows. Is there a way to do this? [closed]
To explain a bit further. I am trying to capture the train coming which you can only see if you turn a bit to the left looking at an oblique angle. I am wondering if there is a way to calculate where ...
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1 vote
1 answer
135 views
How could I manually find the field of view of a camera lens at specific focal lengths?
I'm trying to manually find the fov of my FE 24-70mm F4 ZA OSS Sony full frame lens. I know I can find it on the internet, but I want to do a physics/mathematical investigation myself. I have an idea ...
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27 votes
3 answers
4k views
Why are the northern lights so much less visible to the naked eye than to smartphone cameras?
The northern lights have been visible where I live recently, but I've found them to be practically impossible to see with the naked eye. Phone cameras, however, show them quite brilliantly. How is ...
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1 answer
175 views
Matching $f$-number to FOV
I often read that the $f$-number of an optical system (here a camera and a lens) should be matched to the FOV, but doesn't know exactly what it means. The FOV is determined by the focal length $f$ and ...
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1 answer
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Clarifying Magnification Values in Photography
Question: What is the range of magnification produced by a camera lens? Given the options: (a) more than $-1$ (b) more than $+1$ (c) less than $-1$ (d) less than $+1$ Context: I’m trying to ...
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1 vote
3 answers
729 views
Why do images invert to create a perfect image (ie a pinhole camera)
This image has always confused me, and it seems to be the go to example when explaining why images are inverted when looking through a pinhole camera. I understand that light travels in a straight ...
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-1 votes
2 answers
184 views
Why is a bigger camera sensor better at low light than a smaller one?
People say a bigger camera sensor is better for light performance as the photo sensors are bigger and hence let in more light. But couldn't you just let the same light in and focus it down onto the ...
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142 views
Reflect visible light transmit infrared light
I have a color camera and PIR sensor inside a commercial security camera which records when motion is detected. I want to hide the security camera behind a 1/2 inch polycarbonate window which reflects ...
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2 votes
1 answer
156 views
My phone sees the NIR from a TV remote. Why does it not see the NIR in rainbows?
My Pixel phone's camera shows the IR light from the LED of a TV remote as a magenta/lavender color. That wavelength is likely around 940 nm. Now, when I take a picture of a rainbow in the sky, it does ...
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0 votes
0 answers
96 views
Can I use Gaussian Optics and Aberration Theory to find the direction of a ray from the sensor to the world?
I am working on a master thesis which is a continuation of a previous one, which can be found here, with a nice summary: https://twitter.com/dearlensform/status/1465776613094797319 The thesis is ...
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0 votes
1 answer
100 views
Effect of ambient fluid on a pinhole camera's intrinsic parameters
Suppose I am performing calibration of a pinhole camera under the Brown–Conrady distortion model and find the focal length $(f_x, f_y)$, principal point $(c_x, c_y)$, radial distortion coefficients $...
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