Why do computer screen appear to blink when they are see on a TV eyeshade?
Answers: Computer screen flicker in TV video when the renew frequency and timing of the computer screen is not synchronized beside the TV camera that is film it.
For example, if the TV frame rate is 60Hz (NTSC version 1), and if the computer monitor runs at 90Hz, consequently if you look at the TV video and computer monitor timing, frame by frame, then:
(TV...Monitor) : Effect
( 0.............0) : within sync, picture ok
(60..............) : TV on, but monitor off - out of sync
(..............90) : TV past its sell-by date, but monitor on - out of sync
(120............) : TV on, but monitor off - out of sync
(180.....180) : surrounded by sync, picture ok
etc.
It is the alternating in and out of sync frames that produces the flicker effect.
It is possible to synchronize the timing of the TV camera and the computer monitor, and within higher level video - such as that of a TV news set near computer monitors visible surrounded by the background - the two are synchronized, and so within is no flicker.
* As another post correctly points out, the current NTSC standard has a frame rate of 30Hz (though the strip frequency is still 60Hz), and computer monitors typically run at 72Hz. If you really want to be technical, the example above should use a 30Hz/72Hz ratio, but the 60Hz/90Hz ratio shows the frames moving contained by and out of sync more easily.
Because the pixels of the camera and the pixels on the blind dont match, thus you get a bad little clash of pixels!
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