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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11
votes
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.)
7
votes
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)
7
votes
1answer
179 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 ...
5
votes
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 ...
11
votes
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 ...
31
votes
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 ...
26
votes
2answers
3k views

What is this blue thing in a photograph of a bright light?

It looks like the bulb of the lamp beside it but how why what
2
votes
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 ...
1
vote
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 ...
4
votes
1answer
213 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 ...
2
votes
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?
2
votes
1answer
225 views

Why are filter flare images centrally inverted?

A previous question asked about the origin of the ghost-like image of the fluorescent bulb on this image, which turns out to be something called a filter flare, of which there are more examples here ...
2
votes
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 ...
1
vote
1answer
966 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 ...