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Distortion on widescreen tv's - is this normal?

Discussion in 'Televisions' started by videoman, Jun 16, 2002.

  1. videoman

    videoman
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    I'm noticing some distortion on my new widescreen that I can only explain as stretching of the image at the edges, and compression at the centre. Its mainly noticeable with the vertical or horizontal scrolling text on titles, or if there is a panning image across a flat background. The image is normal in the centre but as it approaches any edge of the screen its seems to stretch off the screen!

    Otherwise the geometry of the picture seems fine and vertical and horizontal lines seems straight even at the edges.

    My TV is a Panasonic TX32DK1 but I'm interested if this is quite a common characteristic with most widescreen's. I could not imagine a top of the range Sony doing this for instance, but maybe I'm being to critical.

    Also are there any testcard DVD's you can buy to check image geometry?

    Thanks,
    Dave.
     
  2. rct

    rct
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    Might not be this but I'll tell you my theory anyway... Panasonic TVs have a picture mode called "Just Mode" which does exactly what you describe. The idea is that a 4:3 picture can be stretched to fill the entire screen without distorting objects completely... as people tend to focus on the centre of the screen. Whether it is good is a matter of personal preference. Look how to change display format/size. Let us know if you figure out the prob.
     
  3. shaunthedude

    shaunthedude
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    This fault you are describing can be a fairly common thing in widescreens. However most of the time this can be cured in the service menu. I cant remember how to access this on the panny tvs but there will be a post here somwhere on how to. If I were you I would get an engineer to do it for you. As for top of the range Sonys NOT doing it. Well, I had 3 sony widescreens all of which were £1700 plus and all of them had geometry problems and one of them had a lot more. I would not buy Sony tvs again. I now have Toshiba and im very happy with it, so far. As for the discs you mentioned, Some of 20th century fox discs have a check system for your geometry. I know the French Connection has it. there is also a disc you can get from Amazon for checking this. A few people have raved on about how good it is in this forums but again I cant remember what it is called. My memory must be going. Hope this is of some help.
     
  4. LV426

    LV426
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    videoman - I'd check out what rct says.

    Are you watching a 4x3 picture in "just" mode? If yes, that is\ what is causing the distortion.

    The only other ways to watch a 4x3 picture are:

    1) with vertical black bars either side
    2) zoomed in so that the top and bottom are cropped off.

    1) is the only "correct" way to do it.
     
  5. videoman

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    Thanks. The effect seems to be in all modes and is even there in 4:3 format. I don't have the picture in 'Just' mode because it does give extra but different distortion. Its either the setup, which maybe adjustable in the service menu or the design of the TV. If they are designed like this (even other manufacturers widescreens) and can't be corrected then I can live with it, but if its a setting or a fault then I want to try and do something about it.

    Which of these service menu options would possibly effect this problem?

    H-pos (horizontal position)
    V-pos (vertical position)
    H-amp (horizontal amplitude)
    V-amp (vertical amplitude)
    EW-amp1(EW-amplitude coarse pincushion looks like)
    EW-amp2(EW-amplitude finer/corners looks like)
    Trapez1(Trapezium comp_ suck it and see!)
    Trapez2(finer of the above suck it and see!)
    V-lin (vertical linearity)
    V-sym (vertical symmetry used with above to sort... vertical linearity !)

    [ripped from MR D & encaser's post.]

    The strange thing is that vertical and horizontal lines are straight
    so I don't think its pincushion effect. I am scared of playing with
    these setting unless absolutely necessary.
     
  6. groundy

    groundy
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    If the cross hatch test pattern grid lines are straight then you have nothing to worry about. I've noticed the kind of effect you are talking about on many Widescreen sets. It's only really noticable if you look for it on left/right horizontal panning shots - the picture at the edges seems to distort ever so slightly. I think it's down to the why the tubes are manufactured but you may very well be able to improve it in the service menu but altering any of the listed settings will also altar the horizontal and vertical lines. That's why I say if they are straight, then leave well alone. :)
     
  7. Stuart Brooks

    Stuart Brooks
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    I would have thought Horizontal Linearity would be the one you're looking for. (Not there in the list though is it!)

    It would be the straightness of diagonal lines on a test card that would show this, alternatively measuring the distance between equally-spaced vertical lines.

    I have noticed a slight similar effect on panning shots, however I wasn't sure if this effect was an artefact of the widescreen camera lens (a sort of slight fish-eye pan effect) or something on the TV.

    Stuart
     

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