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Important! The Response Time Myth.

Discussion in 'LCD & LED LCD TVs' started by Ramspeed, Jul 1, 2005.

  1. Ramspeed

    Ramspeed
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    Just want to open a little debate. There are many people here myself included looking to get an LCD primarily for gaming - and in particular the upcoming hi-def consoles. Obviously we want a great picture - 720p, good colours, good blacks etc. But the biggest bugbear for LCD's has been motion blur. Games move quickly and any motion blur at all is distracting and not what we want to pay a grand plus for.

    There are two things we are routinely told cause motion blur.

    1. Interlaced signals (i.e what you get through RGB scart with a DVD player, games console etc.). This is because LCD's are progressive by nature. They don't like interlaced inputs. I can buy this.

    2. Response times. This is the one that bothers me. Time and time again we're told that the lower the response time the better for handing fast movement. But this does not appear to be the full story. The Panasonic LXD500 series has been much praised for it's effortless handling of fast movement (not a hint of blur or smear) - but it only has a 'mediocre' response time of 14ms. My conclusion therefore is that beyond a certain point (let's say 16ms) an LCD's ability to handle fast movement is determined by other technical factors. I'm not a technician, I don't know what these are. But clearly selling LCD's to us on the basis of ever lower resonse times ( 12, 10, 8 etc) is misleading. It does not guarantee a better ability to eliminate motion blur.

    The problem with magazine reviews is that they never test LCD's with consoles so don't comment on a model's suitabilty for that purpose. Our only recourse is a forum like this. I would be very interested to hear what anyone has to say about this response time/gaming business.
     
  2. David Mackenzie

    David Mackenzie
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    #1 shouldn't be a problem, especially not with the next generation when progressive games should be standard. As we know, numbers/stats sometimes don't mean too much in the real world... best way to tell is to demo what you're going to buy before you put money down.

    My Sony KLV26HG2 is fine for games. Yes, there is dragging on very bright colours and intense blacks and whites, usually on 60fps games. However it's never unbearable.
     
  3. Andy3

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    Interesting comments, Ramspeed and Lyris. A few observations from one who has recently changed from 28" widescreen CRT to 26" LCD:

    On Doom3 (XBOX, 576i/480i) I'm not suffering any undue dragging or blurring. The quoted response time of the JVC DS6 is 7ms, but I suspect there's an element of 'the numbers game' at work here - there may be 'better' ways of measuring this figure, just as there are better ways of rating a cars MPG.
    I have noted that applying too high a level of noise reduction leads to blurring.
    One thing I have noticed since we changed to LCD gaming is a slight motion sickness or light-headedness after a few minutes. I never had this on the CRT.

    One thing that keeps bothering me. We are told that the incoming signal needs to be 'de-interlaced', because LCD panels are 'progressive by nature' and don't like interlaced signals. I don't get this. The panel is (surely) made up of rows and columns of pixels which can be accessed in any way we choose? So why are they 'progressive by nature'? It's like saying CRT's are 'interlaced by nature' when in fact it is the chosen type of transmission that dictates this, and the CRT could (and does!) display progressive just as well!

    (goes for a lie down...)
     
  4. satwar

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    From what I have read at http://graphics.tomshardware.com/display/index.html the problem is marketing hype of display latency.

    Display latency is still making the difference between set performance, the problem is manufacturers' claims of latency or response time can have no bearing on actual performance. They have recently even changed the definition of latency to make the marketing numbers look better.
     
  5. sandstheman

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    One problem is that the Response Time being quoted by manufacturers is usually a best case scenario which is when the pixel changes from white to black and back to white again, the problems start when it's not doing a straight switch to the extreme ends of the color scale.

    Here's a good article, although it is a review of LCD monitors, it does have a good section about response time/latency and the problems of marketing a display as having super fast response times:

    Why Pixel Refresh Times can be Deceiving
     
  6. David Mackenzie

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    I'm not too sure about this, but I seem to remember old (and maybe current) Sharp LCD TVs had the option to switch the panel into Interlaced mode.
     
  7. SIDEARM

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    Great article, thanks sandstheman. I think this shows us that at the current time were not going to find an LCD TV that doesnt smear our games at all, there will always be a certain level of smear, it will just be hard to spot.
     
  8. pjskel

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    TVS are interlaced by default - since it's a legacy aspect of when they were first produced. Same for the broadcast cameras that capture the event.
    The scanning lines are done at the frequency used and interlaced so as to the eye, the whole picture "appears" as being displayed instantaneously.
    Where LCD differs, is that the pixels are addressed individually, hence why DVI from your PC card is the best solution (no D2A and A2D conversions to mess the image up with), and as such, there is no need to display the image as 2 fields 1/25th of a sec apart.
    That's why progressive CRTs were made for the TV market - the scanning rates for PC monitors gave them a rock solid image.
     

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