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Questions tagged [physics]

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4
votes
2answers
123 views

Polarization and Rainbows

Why when I use a polarized lens if I turn it one way the rainbow disappears and the other way it brings it out better to the point you can see the second double rainbow when the naked eye can't? Is ...
1
vote
1answer
54 views

Calibrating monitor with lab spectrometer

I'm trying to calibrate my monitors. But I'm wondering if I can avoid buying another piece of equipment by using a lab spectrometer (in the past I've always just calibrated by eye). I'm a PhD student ...
1
vote
1answer
233 views

Cross Polarization: Are linear and circular polarizers compatible?

Can cross-polarization be achieved with two linearly polarized (flash) lamps; one either side of a circularly polarized lens? Lens attachments tend to be circularly polarized, while the PVA sheets ...
0
votes
1answer
102 views

How to get Canon 1200D quantum efficency plot?

I've searched quantum efficency of Canon 1200D and I found some images like here: http://www.deep-sky.co.uk/imaging/dslr/dslr.htm . How these people get quantum efficency plots for mentioned Canon 40D?...
14
votes
3answers
2k views

Why do polarising filters only work in one direction?

So I bought a polarising filter yesterday that has a dial you can turn to increase/decrease the polarisation effect and mount directly onto the lens. I also have an old polarising filter that was one ...
2
votes
3answers
353 views

Polarizers: Linear vs Circular. How does it affect a photo? [duplicate]

Trying to decide which type of polarization filter I should get. Some information I've read suggests that there is no difference and that a circular polarizer is just an ordinary linear polarizer, ...
6
votes
6answers
717 views

Why is the area in focus in front of the focus distance narrower than behind it?

I guess the title and the picture explain my question well.
13
votes
8answers
860 views

Since the speed of light is so high, why does shutter speed even matter?

When a camera's shutter is opened, if light reaches the sensor instantaneously (speed of light = 300.000 km/s), why does shutter speed modify picture sharpness/detail? Why do pictures get darker with ...
3
votes
4answers
253 views

How much of digital sensor noise is thermal?

Is all digital sensor noise thermal? And what is the relationship between temperature and noise? For example, as we cooled a CMOS towards absolute zero, would we discover that high-ISO images would ...
1
vote
1answer
330 views

How do wavefronts/wavelets propogate in three dimensions, and why is this important for photography?

The photography book I have talks about waveforms, but it doesn't do a good job of explaining them. So, here's my understanding from the book and google searches (it could be unbelievably wrong.) In ...
44
votes
6answers
10k views

Are there cameras that can photograph Wi-Fi/WLAN or mobile phone radiation?

Considering that there are cameras for infrared, X-ray and ultraviolet, I wonder if there are also cameras that can picture the WLAN or mobile phone parts of the electromagnetic spectrum. Considering ...
0
votes
1answer
71 views

Low-light photography: How much light reflects off a surface

I'm looking at light levels for photography and I'm trying to figure out how much light hits my sensor. There are plenty of tables online which give light levels, but that's only directly relevant if ...
6
votes
1answer
820 views

Converting cameras for infrared use: When does the filter have to be replaced, and when is simply removing it ok?

When converting a digital camera for infrared use, the general approach is to remove any filters that limit its sensitivity to the visible range of light wavelengths. Some conversions replace the ...
13
votes
2answers
1k views

In what way does the lens mount limit the maximum possible aperture of a lens?

In many answers to questions about different aspects of really large aperture lenses it's pointed out that the lens mount sets a hard limit on the maximum possible aperture of the lenses to that ...
2
votes
1answer
322 views

What are the main limiting factors for dynamic range in modern cameras?

Another question got me thinking about what is limiting dynamic range in digital cameras. From my understanding the precision of the analogue-to-digital converter, i.e. how many discrete levels it can ...
2
votes
3answers
1k views

How do I know how much light will be needed for a given film speed, shutter speed, and aperture?

For a given film type, shutter speed and aperture, how do I calculate the light needed to get a good exposure? For example, if I use a f/8 aperture, an exposure time of 100 ms and a ISO 800-film (...
10
votes
3answers
3k views

What are the theoretical minimum and maximum apertures?

Is there such a thing as a maximum aperture that a lens can be open to? What about a minimum aperture that it can be closed to? Do these concepts even make any sense? Is there a lens with the ...
2
votes
5answers
466 views

Does an aperture value exist, where a lens creates a brighter image than the real view?

So (without limitations of the viewfinder for example) looking through the viewfinder creates a brighter image than normal view would be. The lens would then work like a funnel(collects light from ...
0
votes
0answers
45 views

Solid explanation behind the physics of the relation between aperture size and depth of field [duplicate]

Possible Duplicate: Technically, why is the out of focus area blurred more when using a bigger aperture? Many of us know that there is a relationship between the aperture size (f-stop) and the ...
10
votes
5answers
4k views

Why is the focus distance for a mirror image further than the surface of the mirror itself?

When I take photographs of a subject reflected by a surface (water, mirror, glass) I notice that the focussing distance is not the distance from my camera to the surface, but mostly it is close to ...
0
votes
0answers
101 views

Technically what happens that aperture affects Depth of field [duplicate]

Possible Duplicates: What exactly determines depth of field? Technically, why is the out of focus area blurred more when using a bigger aperture? It is obvious that the aperture affects DOF. ...
3
votes
2answers
1k views

Assuming a perfect sensor, what is the physical limit of ISO/pixel area?

Assuming that camera manufacturers can eventually make the perfect sensor that introduces no electrical noise to the signal, at what point (measured in ISO/area of a pixel) will shot noise be so ...