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Good contrast PJ 1280x720

Discussion in 'Projectors, Screens & Video Processors' started by stauDLP, May 23, 2005.

  1. stauDLP

    stauDLP
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    Please I need your help to understand if I have to wait until fall to buy my nect PJ.
    I' ve focused on BenQPE7700 and the similar Toshiba, but the contrast spec. does not convince me at all.
    How much more do I have to pay now and how much will I this autumn to get a 1280x720 with a Dark Chip onboard?
    Do you think that dark chip worth such an expense?
     
  2. stauDLP

    stauDLP
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    The PJ you are suggesting haven't the dark chip, so why shouldn't I go for the BenQ that is sold for much less?

    What about infocus 7210, isn't it the more affordable dark chip PJ?

    Do you think dark chip is a rip-off?

    Do you think that, projecting in a room that has not all the black walls around, the dark chip benefits are useless?
    :lease:
     
  3. Kopite4Ever

    Kopite4Ever
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    if your not adverse to LCD then the sony HS50. has a quoted 6000:1 contrast ratio and is 720p native
     
  4. Gary Lightfoot

    Gary Lightfoot
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    DC3 does seem to offer huge improvements over the DC2 equvalent. I measured my H78 with 550 lumens in full lamp mode, but the H79 produces approx 775 lumens in full lamp. The H79 actulay produces more lumens in low lamp mode than the H78 in high - 578.

    There is also an increase in CR from approx 2400:1 to 2900:1 @D65. The H78 may actulay be less than 2400:1 @D65.

    The above numbers ae all genuine measured figures and not advertised figures which are normaly achieved under non video optomised conditions.

    Unfortunately the H79 won't be coming to the UK (as far as we know), so the IF 7210 may be you best bet for DC3 at an affordable price. It will be interesting to see how the 7700 performs though, considering its price.

    Gary.
     
  5. stauDLP

    stauDLP
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    OK, I think I' ll take a look at the PJs you suggested me.
    But please.... tell me:
    how much do you think the surrounding wall can impact on contrast ratio?
    For istance a 2000:1 PJ in a perfect home theater room become a xxxx:1 PJ if used in a normal white wall room?
    Have any calculations been made untill now?
    Do you suggest to hang pictures on the wall?
    My wife would be happy.... :thumbsup:
     
  6. lukemh

    lukemh
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    Be careful when looking at the spec sheet that they actually use the ANSI standard to measure the contrast levels there are many ways and many tricks to bump it up
     
  7. Gary Lightfoot

    Gary Lightfoot
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    Light coloured walls have more of an effect on ANSI contrast which is the measured contrast between black and white being projected at the same time - the ANSI contrast test is done using white and black squares simultaneously. If you have light coloured walls, the white portions of the projected image bounce off of the screen and onto the walls, then back again, washing out the black areas on the screen and redudcing the ANSI contrast. This effect happens to some degree within the lens as well. Light coloured walls have less of an impact during full black scenes and full on/off CR as there is little light to reflect when 'projecting black'.

    Advertised lumens and contrast are normaly done using full contrast with RGB levels and contrast maxed out, so the image will have little or no bright detail and very poor colour balance. Black level will be similarly devoid of detail by having the brightness reduced, and if the machine has a white segment or white peaking, this will be turned on to further increase light output. None of this does anything for good video reproduction. Reversing the above can typically reduce lumen and contrast figures by around 40% or more.

    If you compare my H78 measurements from my post above, you'll see they are somewhat less than the advertised figures. As far as I know, Infocuse quote accurate figures for lumens and contrast, but I believe this is with the white peaking feature switched on.

    By all means hang pictures on the walls, but the less reflective the frames and glass are the better. Having unwanted reflections on the projected image can be quite distracting.

    Gary
     
  8. stauDLP

    stauDLP
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    Thank you Gary, finally I start to understand!!! :thumbsup: :clap:
     

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