When watching something electronic, such as a phone or camera on a video, why does the screen flicker rapidly?
In: Technology
Screens don’t have a constant image on them, or a fluid moving image. What they do is present you a series of still images so fast that your brain blends them together. The entire screen is constantly in the process of “scanning” or “refreshing” the image.
Video cameras do the same thing. They take many frames per second and link them together into a video. When they are played together you don’t notice the jumps from one frame to the next.
If you point a camera at a screen the rate the screen is refreshing and the rate the camera is recording frames won’t be the same. So instead of a fluid image you see one that looks flickery, or like lines are moving across it.
The same principle gets you [very weird looking videos](https://www.youtube.com/watch?v=yr3ngmRuGUc) if you try to film a thing moving very fast.
Because the screen sometimes updates at a different rate than the camera records. Which means that some frames are in between two frames on a phone screen, for example.
Because those images are in fact flickering rapidly.
The flickering happens so fast our eye blends the images together, creating the illusion of motion. But cameras aren’t fooled, they catch the screen in mid flicker and send that image along to us.
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