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According to physics, our current understanding has space and time as continuous entities. Photographs generally work by letting light modify a surface by striking it and it forms the picture. The question is, do photographs capture very small intervals of time, or do they capture instantaneous moments? If they do capture small intervals, how does that reconcile with the concept of a picture of non-moving images?

Anyone that knows way more in photography or microscope technology, please feel free to correct/educate me if I have made a mistake in this question.

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  • $\begingroup$ Hi, new fella! You should know more than this to begin with, since presumably you have heard of "shutter time" in cameras (for example). You might want to read a bit about how both film-based and solid-state cameras work too. $\endgroup$ Aug 12, 2021 at 14:53

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They certainly do not capture instants of time. A camera needs to capture light for a certain period of time in order to create an image. On most cameras, the duration of the period can be adjusted to suit the lighting and the type of image to be captured, by setting what is known as the 'shutter speed'. The shutter speed might vary from, say, 1/8,000th of a second to one or more seconds, typically over a range of pre-set values where each is around half of the next.

Specialist scientific instruments can capture images of much shorter durations of less than a millionth of a second. However, there is a practical limit on the duration- if it is much less than the mean time between the emission (or reflection) of photons by the subject, then no light will be captured and thus no image formed.

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  • $\begingroup$ So the fact that they capture intervals and not instants is the explanation for stuff like motion blur, right? $\endgroup$
    – Chidi
    Aug 12, 2021 at 6:28
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    $\begingroup$ Indeed. To avoid blur, one increases the shutter speed- to accentuate blur one reduces it. $\endgroup$ Aug 12, 2021 at 6:36
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    $\begingroup$ In addition, the speed of light is limited, thus objects far away from the camera are "older" than objects close by (think on telescopes in astronomy looking into the passt). $\endgroup$ Aug 12, 2021 at 6:57
  • $\begingroup$ ... and high speed filming or photography requires bright illumination to compensate for the shorter exposure time of each frame. $\endgroup$
    – gandalf61
    Aug 12, 2021 at 9:46
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  1. The light doesn't travel instantaneously.
  2. In case of Electrochemical photography, the chemical reaction does not occur instantaneously. And in case of digital photographs, the conversion of photosignals to electrical current does not take place instantaneously. It also takes finite time for processing of individual photopixel to produce whole photo.

In taking both these points in mind, it's obvious that phographs don't capture instant of time, instead a duration of time. To verify this, you can take a picture of a moving fan or a bullet. Obviously you won't be able to take its clear photo.

Now, how to reconcile that the photo is still image. Well, take a paper and doodle a pic of your crush (if you have any :-) ) . Clearly you will take finite time to do so. But this doodle is also still(non moving) image.

On another note, if cameras or any instrument were able to shoot an instant of time, then the Heisenberg's uncertainty principle would have been proved false.

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