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50 hz or 100 hz

Discussion in 'TVs' started by sparkrite, Mar 20, 2001.

  1. sparkrite

    sparkrite Guest

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    ok people ive decided to buy a 32" widescreen,it doesn't need to have pro logic/surround as i have a sony stb 940 and speaker set up already in place. it has to have ntsc playback but thats about all "must-haves".Any recommendations would be gratefully received,also views on whether i should go for a 50 hz set or 100 hz (i watch a lot of sport (digital sat) and dvds).price range up to about 1300.Many thanks
  2. LV426

    LV426 Administrator

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    This is a general comment on 50vs100hz. I don't mean to imply any preference for Manufacturer or Model etc....

    Here goes....

    The PAL TV standard shows pictures at 25 frames a second. Each frame consists of two fields. So, the field rate is 50 fields per second.

    This means that the light on the front of your TV screen is flashing on and off 50 times a second. This is 50hz flicker.

    A percentage of people (yes, I'm one) find this flashing tiring on the eyes. It gets worse, the larger the screen area and the brighter the image.

    A 100hz TV basically takes each frame, holds it in a digital memory, and displays it twice before moving on to the next. So the flashing happens twice as fast, i.e., 100 fields per second (100hz). This is, for people like me, MUCH MUCH more relaxing on the eye.

    BUT: This digital processing usually results on some degradation of the detail in the picture. Some sets do it better than others.

    So, in order to make a choice you have to first decide whether you can "see" 50hz flicker. If you can't, then, if nothing else, 100hz is a waste of cash.

    If you can, then, like me, you immediately discount all 50hz TVs from your shortlist and go find the best 100hz processing you can afford.

    If you ARE one of the ones who "see" it, then you will get little sympathy from others here who can't. They just don't understand how tiring to watch a large 50hz picture is. Even to the point where a little smearing here and there is actually better. It would be for me.
  3. mart.stokes

    mart.stokes Guest

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    In short I would say buy a 100hz set where you can turn the processing off when needed so it reverts back to 50hz (there is nothing worse than a football with a "trail" behind it). Given what Nigel says above (which I have always also believed to be true) I can never understand why you get these effects. Showing a frame twice should not give movement problems, there has to be more to it than I believe. 100hz processing is getting better all of the time though as new models are released.
  4. Jeff

    Jeff Active Member

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    If you mainly watch R1 DVDs 50/100 Hz doesn't come into it because R1 uses 60 Hz.
  5. LV426

    LV426 Administrator

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    FWIW, I believe that the smearing that 100hz TVs often show is not a direct result of 100hz processing, rather it's a result of noise reduction processing. In an attempt the reduce the amount of noise in the "colour" part of the picture (which is often the most intrusive) processing averages out the colour component of a few consecutive frames. This reduces random noise, but also gives rise to smearing. I suspect that most manufacturers apply noise reduction in tandem with 100hz processing.
  6. Mr.D

    Mr.D Active Member

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    50 (or 60) fields per second video. When you deinterlace two consecutive fields with each other you get a mismatched frame not a "real" frame as you do on progressive sources (ie films).

    100 Hz TVs are not great at telling the difference between the two field arrangements so you get additional (unnecessary)interpolation on matched field material as well as the disparate field video material.

    Its not a simple as showing the same frame twice.
  7. Ludae

    Ludae Guest

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    Other than Sony's DRC equipped models, no 100Hz TVs I know of can switch to plain 50Hz mode. Many will allow you to switch to a simple field repeat 100Hz mode that will be evident by the line flicker introduced and may well improve picture quality from your point of view, this mode uses much less picture processing.

    Some noise reduction systems can cause smearing and multiple imaging on motion and are best turned off.

    Repeating images (which also happens on 50Hz TVs for film source) causes judder and blur on motion scenes. It is a psyco-visual effect and its severity is a function of the viewers sensitivity, size of image in the field of view, amount of motion between fields/frames and the number of times the image is repeated. The latter element, i.e. the number of times the image is repeated doesn't increase judder appreciably but does increase blur, therefore a 100Hz TV is going to have more motion problems that a 50Hz TV.

    These repeat image artifacts are a result of the way the eye naturally tracks motion so the only way to eliminate them is to display video at the source native frame rate or increase the motion phases in the video to match the display refresh rate.

    All 100Hz techniques beyond the simple repeat field methods, use de-interlacing to create the extra 50 fields per second and help eliminate the 25Hz line flicker problem. It is the sophistication of this de-interlacing that is the cause of most of the imaging problems beyond those already mentioned.
  8. Jeff

    Jeff Active Member

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    Sony's can't switch from 100Hz to plain 50 Hz.
  9. MikolaH

    MikolaH Guest

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    How about Panasonic PG50-line? Is their progressive mode real non-interlaced 50 Hz? I´ve got some very good results from a high quality (not progressive) mode source.

    Hannu
  10. Ludae

    Ludae Guest

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    True. I didn't intend my statement to suggest they did. Poor syntax on my part.

    The DRC50 mode has the same scan rate as the DRC100 mode and is sampled and buffered in each case.
  11. Ludae

    Ludae Guest

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    The Panasonic PG50 CRT TVs will operate as progressive scan at 50 and 60Hz or interlaced at 100 and 120Hz.
  12. beefybeef

    beefybeef Guest

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    Just a point about whether you can actually 'see' the 50Hz flicker. You MAY not be aware of it but it can still affect your eyes and cause strain, much like a computer monitor running at a refresh rate of 60Hz. Try looking slightly away from the TV, and you may notice the flicker out of the corner of your eye.

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