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LCD & DLP Black Levels ??

Discussion in 'Projectors, Screens & Video Processors' started by coldfact, Jan 21, 2004.

  1. coldfact

    coldfact
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    Hey my fellow Japaties! Well after a week with a Z2, I have to say I am not overly impressed. Maybe I have been spoilt by first owning a NEC vt540, I don't know... Sure, its hard to argue with the incredible Lens Shift feature and the true 16:9 widescreen of the Z2, but the contrast levels and general black levels are not as good as I imagined they were going to be. To see any real difference between this and my NEC, I had to put the lamp on dim and turn the optical iris right down, which took a lot of the general brightness out of anything I watched, so I would be constantly adjusting the iris to improve contrast in dark scenes, then opening it up again to get light back for bright scenes. Well, it can get quite frustrating. I have not bought a Z2 yet, this is a demo from Sanyo, so I have time to look around still and might take a look at the Panasonic AE500 to compare.

    But what I really wanted to know is this, from anyone with experience of the newer DLP projectors: How much light is projected on a completely black screen? When an LCD projector, even the Z2, projects a completely black screen, there is a rather disappointing dark purple instead! How does this differ from a DLP with a contrast ration of say 2000:1? In an LCD projector, the light shines continuously through the panels so that even when the pixels are black some light still gets through. In a DLP projector the light is reflected off millions of tiny mirrors but only when they are tilted. So it seems that the only light that gets through in a black scene would be light spill from the internal construction flaws of the unit.. or am I completely off?

    thanks, and happy Japatying!
     
  2. Gary Lightfoot

    Gary Lightfoot
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    The dark purple is probably the projector needing calibration, and isn't unusual, and the black level is exactly for the reasons you say for both technologies respectively.

    You may be able to improve black level by calibrating with (Avia or similar) - the needle pulse tests allow you to set the white and black levels so you could improve your blacks if the brightness is too high.

    Gary.
     
  3. The Nightfly

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    coldfact,

    Even with a 2000:1 contrast ratio from a DLP you can still see quite a bit of light on the screen when projecting nothing but black. The eyes are quite sensitive and will continue to adjust well beyond the capabilities of pretty much any digital projector. My guess is that something like 10000:1 should be good enough to convince you that the screen is REALLY black (or at least black enough).

    Having said that, with a 2000:1 contrast ratio, even with very dimly lit scenes your eyes can be fooled into believing you can see true black in the image.

    Allan
     
  4. buns

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    The contrast ratio issue has been discussed elsewhere and it is clear that myself and others will always have differing opinions. In my view, unless we start to increase contrast ratio by orders of magnitude, then black levels wont be changing much.

    the Z2 does have purple blacks, i think this has been reported by multiple sources worldwide. It can be helped with proper calibration though.

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  5. WeirdFish

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    Well purple is the new black



    :)
     
  6. Quatermass

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    :laugh:

    If you want to test your Z2's purple capabilities there are some nice ones in the newly restored version of "The Adventures of Robin Hood" - thought the Z2 did them pretty well :)

    (Watched it the other day - incredible colours for a film that is getting on for seventy years old :eek: )
     
  7. gingercat

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    I thought we were all after recreating the authentic cinema experience here - I've never seen a true black at the cinema! (Doesn't help that health & safety regs mean they keep the lights on dimly...)
     
  8. greenmachine

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    I would imagine most people would strive for a better experience than there local cinema environment!
     
  9. Gary Lightfoot

    Gary Lightfoot
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    Yes indeed - it isn't too difficult either judging by the local Cinemas I've seen anyway. :)

    Gary.
     
  10. gandley

    gandley
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  11. Gary Lightfoot

    Gary Lightfoot
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    It's been quite an interesting read, and I'm looking forward to finding out how it actualy works. Lots of conjecture at the moment. :)

    Gary.
     
  12. buns

    buns
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    Gordon already did comment! He was exceptionally positive.

    The only thing concerning me about that thread is it highlights that alot of people who think they know what is going on actually dont...... of course i feel obliged to point this out! :D

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  13. Gary Lightfoot

    Gary Lightfoot
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    That's what I like to hear Ad!

    What do you think it could be then? It sounds like an internal mod driven by an external device - possibly a video monitor box that decides when and how to operate the device.

    Sound like a huge step forward for digital if it works. :)

    Gary.
     
  14. buns

    buns
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    Well Gary, were you to ask me right now to build something, i wouldnt do anything as mechanical as an iris nor something as electrically stressful as modulating a lamp directly. Simplest thing would be a variable with light intensity filter, either as something prior or following the panels, or somewhat better (and i suspect beyond immersive) would be to make a panel of said filters. So basically you have 3 chroma panels and a 4th one for luminance.

    easy! but i dont know if that is feasible!

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  15. Gary Lightfoot

    Gary Lightfoot
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    What about something that'll work with DLP?

    Gary.
     
  16. buns

    buns
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    same thing would work with dlp...... your 4th panel could be transmissive or reflective

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  17. Gary Lightfoot

    Gary Lightfoot
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    Any mention of when they'll release the details of this? There was an nda the last time I read the thread, but I can't remember if they said when they could tell us how it really works..

    Gary.
     
  18. buns

    buns
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    no one has said anything....... i doubt many people really know the whole story and even fewer when it will actually become available

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