Do RPTVs have geometry problems?

Discussion in 'Archived Threads 2001-2004' started by NickSchmidt, Oct 3, 2002.

  1. NickSchmidt

    NickSchmidt Agent

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    Because my flat screen direct view 27" Toshiba has hella geometry problems. No matter how much I tweak the service menu, I still can't get it to display any straight vertical or horizontal lines. Is this a problem with RPTVs too? And why the hell can't companies make TVs that display straight lines?! [​IMG] [​IMG]
     
  2. Gregg Loewen

    Gregg Loewen Video Standards Instructor, THX Ltd.
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    with all TVs you get what you pay for. The only way to make a direct view with minimal geometry problems is to make it deep. Deep means heavy and EXPENSIVE (read 30,000 range). I did see a real nice Sony 16x9 studio monitor at Sony's DVD Transfering Studio in LA a couple of weeks ago. It was 34" and cost $35,000.

    FWIW,

    Gregg
     
  3. Allan Jayne

    Allan Jayne Cinematographer

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    Yes, RPTV's can have geometry problems too because they use CRT's to create the picture.
    RPTV;s have their own set of complexities, getting all three sub-images (red, green, and blue) to be the same (convergence; registration), and this may make it more difficult to get the geometry correct.
    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  4. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings
    You know, if $100K Runcos don't have perfect geometry either, then why this expectation at $600?
    These things are not perfect nor are they marketed as such.
    As Joel Silver once said ... "yes, I can fix it, how much money do you have? ... " [​IMG]
    Regards
     
  5. NickSchmidt

    NickSchmidt Agent

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    Allan, that link you showed me is scaring me into not getting a new tv. [​IMG]
     
  6. Bill Slack

    Bill Slack Supporting Actor

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    You should end up being much happier with the geometry (after adjusting it in the service and convergence menu) on a RPTV. It still won't be absolutely perfect, especially at the edges, but it's much nicer than any consumer DVTV I've ever seen.
     
  7. Jan Strnad

    Jan Strnad Screenwriter

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    Define "straight." You should be able to adjust the set to give pretty-much straight lines, especially to the point where geometry errors aren't noticeable on ordinary viewing. "Perfectly straight" is another issue.

    Sounds to me like there's something wrong with your set.

    Good luck,

    Jan
     
  8. JasonRH

    JasonRH Second Unit

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    Micheal TLV,
    Many of us probably aren't aware of the fact that those ultra-expensive sets are lacking perfect geometry, therefore it's a valid question to think that you should be getting, at the very least, very good geometry. The fact that many sets are tweakable enough to get very good geometry also supports the fact that it is more than possible to achieve very good results and thus, we can expect the manufacturers to set up the sets well when they are first assembled and adjusted.

    I've seen sets with horrendous geometry and some with near perfect (to the eye) geometry out of the box, so it's obviously not just a limitation of the technology at a particular price point, but a limit to the care taken when the sets are initally set up.

    As far as the sets not being marketed as perfect, one of the points some manufacturers use as selling points is that "flat screen" models allow for better geometry (see Sony descriptions, for example), thus getting the consumer to not expect obviously bowing lines on a new set. I realize that flat screens probably amplify problems and make them appear worse than they are but the end result is the same.
     
  9. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    Flat tube designs are notorious for having geometry issues that simply cannot be easily fixed. In time, they will get better, but not yet.

    For better geometry in a direct view tube design, it is better to stick with near flat screens.

    The nice thing about CRT based RP and FP systems is that at least you can improve your situation somewhat. On a DV unit ... you are generally hooped. The rule is ... if the geometry issue is asymmetric in nature ... (only on one side ... ) you are stuck.

    Regards
     
  10. JohnnyG

    JohnnyG Screenwriter

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    Which begs the question: why don't direct view sets have digital convergence? If you can do it in a projection CRT, why can't you do it on a direct-view CRT?
     
  11. Bill Slack

    Bill Slack Supporting Actor

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    Because direct views use a single CRT, as opposed to projection sets which use a separate CRT for RGB.

    I have seen so many flat-screen TVs with atrocious geometry/convergence problems its astounding. I always recommend buying a larger curved screen. Do you really notice the curvature of the screen on a 36" set in the darkened viewing area? It never bothered me, but a swimmy picture with crooked lines and convergence way off at the edges sure does, which is what my friends $1200 Wega looks like.

    Out of the box, my RPTV set had terrible convergence and the geometry was so bad in HD mode that I re-did it from scratch. The edges are a bit crooked, but not too bad. It's almost impossible to get it perfect, which is frustrating. I have everything with about 1-2mm, but there are still problems, though it's rarely noticeable.

    I'm really attracted toward fixed pixel displays because of this. With the improving contrast ratios I'm pretty set on buying a FP LCD or DLP display as my next set. While the color saturation and black level won't be as good (though, like I said, certainly improving rapidly) the idea of perfect geometry/convergence, and no blooming really excite me.
     
  12. Steve Schaffer

    Steve Schaffer Producer

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    The last over 25" direct view set of any type flat or curved I've seen in the last year or so that had decent geometry is the 32" JVC that my dad bought at Sam's Club last year for about $500--and that was probably just dumb luck.

    I've had 27", 32", and 35" non-flat Sonys in the last 10 years, and the only one with really bad geometry out of the box was the 35" KV35XBR-48- a 98 model. It's service menu did allow for correction on all 4 sides, and I was able to make it look pretty decent on all but test patterns.

    I've also had 4 rptvs in the house since early 98, all of which have had better geometry than I usually see on most 32"+ direct views.

    At least with an rptv one can usually get acceptable geometry by doing a manual convergence.

    Of course this all depends on what you consider "acceptable". If I'm looking at a 57" screen and a straight line is curved by a few millimeters I am not going to see it except on a test pattern.
     
  13. EricHaas

    EricHaas Supporting Actor

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    If you want perfect geometry, get a plasma TV. I'm not saying they are inherently superior to other display types. I'm just saying, if you want perfect geometry, plasmas TV's are pretty much it.
     
  14. Dreama Slay

    Dreama Slay Auditioning

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    Our Toshiba 50" has horrible geometry. When we first did the 56pt convergence, the graph lines at the top started out and then disappeared off the screen becuase they were so crooked.
     
  15. Bill Slack

    Bill Slack Supporting Actor

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    You can fix that geometry on your set by adjusting the green convergence grid to be straight and then converge the other two guns to green (you use green because it's the gun in the middle -- if you try to converge anything to R or B you'll likely stress out the convergence grid too much and force the CRTs into shutdown mode [trust me, I've screwed it up before! [​IMG]])
    I would recommend some sort of grid, or at least strings (which are a real pain, imo) so you don't have a really screwed up looking picture.
    The very corners in my screen aren't perfect in HD (though increasing the overscan to ~5% helped a lot) but the 480p is quite good. It doesn't converge perfectly in the corners either, but it's rarely a noticable problem.
     
  16. Dreama Slay

    Dreama Slay Auditioning

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    Yeah, we did that with the string, but was kind of worried that perhaps we weren't supposed to be actually changing the lines.
     
  17. Jan Strnad

    Jan Strnad Screenwriter

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    Dreama,

    Definitely change those lines!

    Jan
     
  18. Doug McDonald

    Doug McDonald Auditioning

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    Both convergence and geometry can be fixed to perfection
    on any set at the expense of artifacts by simply putting
    the picture in a frame buffer, and remapping that to
    a second frame buffer with an adjustable map, than
    displaying that. This could even be done in a
    box between the picture source and the monitor, most
    easily of course if the connection is RGB.

    Does anybody actually do this sort of stuff?

    Doug McDonald
     

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