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What is flickering?

Discussion in 'TVs' started by angra, Jan 11, 2005.

  1. angra

    angra
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    I'm always reading about flickering in 50Hz TV's, but don't know what that really means (English is not my 1st language).

    Can someone explain what flickering is? Any pictures of it?

    Thank you.
     
  2. Nick_UK

    Nick_UK
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    Consider a light turning on and off continuously once a second. Your eyes would see it going on and off. Now speed up the on-off cycles. When we get to the point where it is turning on and off about 60 times a second, the lamp would appear to be on continuously (although a little more dim). Less than that, and your eyes would still see that the light was going on & off, which we call "flicker".

    TV pictures are repeated 50 times a second on the PAL system (actually, it's 50 half-pictures), but unfortunately some people still perceive flicker at 50Hz. NTSC mainly uses 60Hz (60 pictures a second), and people see a lot less flicker at this rate. The best way of observing flicker is to go to a big store with lots of CRT TV's on display, because the eye perceives flicker more at the edges of the visual field. So if you look at one of the screens, all the other screens will appear to flicker more. Because LCD and plasma screens generate pictures in a totally different way, flicker is a lot less of a problem. Some CRT TV's use 100Hz scanning, which basically shows each 50Hz picture twice, so eliminating flicker.
     
  3. dvdsubtitles

    dvdsubtitles
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    I am not sure if this works for others but I have found that the easiest way to percieve flicker is to move my head (and eyes) from side to side while looking at the screen. My environment moves smoothly around me, but the TV picture jerks and flickers wildly.

    I find it very easy to tell if the picture is 50Hz or 100Hz by doing this. I can't directly perceive flicker while watching a 50Hz tv but I do find watching a 100Hz TV significantly more comfortable.

    Mat
     
  4. shymonk

    shymonk
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    when i walk past my living room i catch a peek of the tv through the crack in the door frame with 50 hz its one line.....with 100hz its two...no help i know but real
     

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