DLP and LCD 'blacks' comparison Z4 and H78

Discussion in 'Projectors, Screens & Video Processors' started by Peter Parker, Mar 26, 2006.

  1. Peter Parker

    Peter Parker
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    A short while ago it was mentioned that LCDs had grey blacks, despite the very high contrast ratios claimed by some projectors which use an iris. Oakleyspatz mentioned that and I wondered why that was the case considering that a 7000:1 CR pj will have considerably darker black level than a DLP with only 3000:1 CR (provided the white level was equal on both).

    I saw Donny Darko's Sanyo Z4 yesterday, so I managed to see what was going on, and what Oakly had been seeing. The truth is a bit of both!

    With the Z4 in vivid mode and the auto iris working, we measured a contrast ratio of over 8500:1. This was after setting the white and black levels, but not at D65 or indeed anywhere close to good colour balance, but the CR would be higher still if we ramped up the contrast further.

    Anyway, with the iris shut down, we were getting deep blacks. With the iris open and the lamp on full (I think it ramps the lamp up and down too), we were getting about 46ft lamberts of reflectance on my screen. That's plasma levels. That put the black level at about 0.005FL. My H78 at 9FL and 2650:1CR gives a better black at 0.003FL. But read on.

    What I did then was add two sets of lens filters to dim the Z4 image down to approx 12ft lamberts (cinema levels of reflectance), and then we produced a black field with two moving bars (Avia's needle pulse test pattern - T1C4). We could still see the moving bars, but the black level was almost as deep as a CRT which had been set for shadow detail (no gamma tweaks to allow FFTB). The black level was now 0.001FL. :)

    Now here is the difference between a native 8500:1 capable pj and the Z4; in mid average picture level scenes where the iris wasn't working, the native CR of the pj was visible - the blacks were much greyer and not as black as my H78 (given that that is currently runing at about 9FL). I think we measured a CR of about 1200:1 in one mode, which was probably closer to the native CR of the Z4.

    So, if an iris is working and working well, the black levels will be better than a DLP, but when it isn't, the DLP will still have better blacks. It's all down to the iris and the implementation, and what calibrating to D65 will do to the white level.

    HTH

    Gary.
     
  2. Timbo21

    Timbo21
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    Good to have a person of your experience checking this Gary. So, you'll be getting a Z4 then ;) ?

    Just to let you know I reduced the green brightness on my H79 by the same amount I had on my 7205 & that seems to have improved blacks greatly. However, I'm looking forward to get a proper calibration on it, perhaps with an fl-day :D .

    T.
     
  3. Darko

    Darko
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  4. Zag

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    At last an explanation of why I was so disappointed with the true contrast on the Z4 I owned for a while, after coming from a 2000:1 contrast DLP machine. True contrast of the DLP wouldn't of been 2000:1 but explains why I thought the black level on a lot of bright/dark mixed scenes didn't quite match that of my old Optoma H30.
     
  5. cyberheater

    cyberheater
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    But this is uncalibrated to D65. I would expect the cr to drop to nearly half that when fully calibrated.

    Still. Very interesting. I can't wait to see what the next generation of DLP machines will achieve with similar iris techniques. Very close to CRT I would imagine.
     
  6. Oakleyspatz

    Oakleyspatz
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    But the problem with an auto iris giving this kind of contrast ratio is that you will never get bright whites and deep blacks in the same image as with DLP. The auto iris reduces brightness in bright images and increases it in dark images giving a 'manipulated' cr figure. DLP through its inherent technology is able to achieve genuinely darker blacks and bright whites at the same time which is something LCD has always struggled with. A man in a black suit standing on a snow covered landscape will nearly always look better on DLP than on LCD....IMO!
     
  7. Peter Parker

    Peter Parker
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    I did like the picture the Z4 was giving - no VB or SDE, and the image looked detailed and smooth. I'd be interested in seeing how the Sony HS50/60 and PJTX200X work as they use their iris in a different way, and the Sony at least uses gamma manipultion to achieve good blacks and bright detail at the same time.

    I do wonder why DLPs havn't used an auto iris yet though. They work well with fixed irises or manual irises that are user adjustable, so I would have though an auto iris was the next obvious step.

    Gary
     
  8. Peter Parker

    Peter Parker
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    Hi Oakley,

    Exactly right. Unless you can manipulate the gamma and boost the video signal when the iris is shut (like the Sony Ruby and possibly the HS50/60), you will just get a dim picture.

    Gary
     
  9. Oakleyspatz

    Oakleyspatz
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    The Mitsubishi HC3000 that I reviewed here has an auto iris. With it in use the cr is claimed to be 4000:1 and without it 2800:1 which is still respectable.
     
  10. Peter Parker

    Peter Parker
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    I think you'll find it's a manualy selectable iris postion, not an auto iris, so you have to tell it which position to use via the remote. It won't open or close automatically depending on the scene content like the above LCDs do.

    I still think it's a good idea though, because you can select either low CR and high brightness or high CR and less brightness, depending on content or perference.

    Gary
     
  11. Timbo21

    Timbo21
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    How did you find the overall effect of the Z4 Gary? I found the Panny AE700 to give a rather clinical image, whereas DLP gave me a more cinematic feeling.
     
  12. Zag

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    The manual IRIS on the HC3000 was indeed a good idea. As another one of my recent projectors :( I found this feature very handy on the machine. I think the DI approach for DLP machines is something they are keeping in their back pockets until C2 fine type technology reaches LCD.
     
  13. ROne

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    I consider the native contrast of the z4 to be in the range of 500:1 and 1250:1 depending on preset, this is without lamp Iris on. With auto lamp iris applied and D65 attained in presets that are the best (LIVING, CREATIVE CINEMA) you can measure around 1300:1, depending on adaptive lamp mode.

    There are so many combinations on the Z4, some having adverse effects greyscale tracking, others having adverse effects on the iris - that it tends to be a mammoth task to try all of them out.

    That said I know you can get a nice 1250:1 at D65 with decent iris operation.

    However something not to overlook which I have said many times, though not measured it - the ANSI contrast for the Z4 looks to be better than the Z3 by quite a reasonable chunk.
     
  14. Darko

    Darko
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    The Z4 is great but you could drive yourself mad with the whole tweek abilty (it nearly did Gary) there is so many variations to play with that you could end up going bonkers but I believe that somewhere in this ugly silver box the perfect settings exist.:thumbsup:


    Darko
     
  15. Zag

    Zag
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    That's not ugly but this it. Check out this pic of the new Optoma HD7100

    http://www.cigarbest.com/sales/hd7100pj1.jpg

    Off topic I know but it does look hideous
     
  16. Darko

    Darko
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    I think the big question is...with all this technology why have these massive companys not employed a designer for the caseing, apart from the hitachi which looks lush, these new creations in the projector world look naff ( this is coming from a Z4 owner) .

    Come on for a grande we want ferrari styling:lesson: :lesson: :lesson: :lesson:

    Darko
     
  17. Peter Parker

    Peter Parker
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    I actually liked it TBH. Much better than the LCDs I'd seen before, and this one looked a bit smoother (possibly due to the h720 res) but still detailed, only the grey spoiled it. I prefer my H78 though, but would still like to see the Sony and Hitachi if possible.

    ROne,

    I could have taken some ANSI measurements but didn't. That's something I'll have to remember to do next time I measure a pj (if I'm lucky enough to get an opertunity like this again). What numbers did you get (did you use the normal 8 black 8 white pattern and average them out)?

    Gary
     
  18. ROne

    ROne
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    Gary, no I didn't measure the ANSI ...

    I just noticed when swapping between the two projectors at the time (Z3 to Z4) that it appeared to delivery a much better *subjective* ANSI than the 3.

    Otherwise, and this is the rub, the ON/OFF CR ratio between the two projectors is actually quite close.

    I'm kicking myself for not measuring it now.
     
  19. Peter Parker

    Peter Parker
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  20. foghorn

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    Hi Gary,

    I hope you get a chance to try the HS60 against your H78; I would be interested to see how you felt they compare.

    Rainbows aside I still have a soft spot for DLP, having said that there are times that the HS60 surprises me at how good a projector it is. I watched the opening scene from Gladiator again last night and it was really difficult to be critical.

    If only I lived a bit closer to you I would have happy to let you put it through its paces.

    Foghorn
     
  21. Peter Parker

    Peter Parker
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    Hi Fog,

    It wasn't a comparison as such, as the H78 wasn't fired up, but it was interesting to see how the black level and contrast was attained.

    I'd love to see the HS60 because I think it may work in a similar fashion to the Ruby, so could possibly maintain better blacks throughout the range. How do you think it looks in various scenes? Does the black level change and does it become grey in some scenes, and black in others?

    Gary
     
  22. squibbly

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    Must admit, I'm delighted with the Z4 still, after 5 months use and 300 hours. It does have an incredibly stable and clear image, though my Pioneer 868Ai helps here. It is also as good as anything I've seen for normal to bright images - quite beautiful . I suppose this is the ANSI CR coming into play.

    The black levels (and I use ROne's settings) are better than I expected for LCD, but occasionally, in dark scenes, when it's 2.35:1 and the bars are showing on my 16:9 screen, I do yearn for something a little deeper.

    I keep hoping ROne will compromise and come up with a setting that uses a slightly stronger auto iris setting and sacrifices a little bit of the D65 colour accuracy (are you listening ROne :hiya: ).
     
  23. ROne

    ROne
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    :devil:
     
  24. bravogolf

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    I noticed a lot of you reference your settings ROne. I plan to buy a Z4 this week, can I get a link to those settings :) ?
     
  25. squibbly

    squibbly
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    Cllick on ROne's name in his message. Select the option that allows you find other messages by him then select Z4 tweak thread. He helpfully makes sure the first message in the thread has the most up-to-date settings.
     
  26. bravogolf

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    Excellent, thank you :)
     
  27. ELV

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    The exterior design of the Z4 is one of the reasons i bought it, it sits on a pine chest out of the way when not in use so the lens cover is a winner!
     
  28. foghorn

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    Hi Gary,

    Had a close look at a couple of films (LOR, Gladiator) and I can't say I noticed a change in the black level. That does not mean that the HS60 does not do it. Given that the Auto iris feature is still in its infancy I would be surprised if there was not some adjustment during viewing.

    If you could suggest a scene or scenes from a film that would possibly expose fluctuations in black level let me know, I will give it a try.

    Foghorn
     
  29. Peter Parker

    Peter Parker
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    Thanks Fog,

    I can't think of a scene off the top of my head right now, but varying scenes of light and dark may give some clue to how the iris and gamma work. Avia has some windowed grey scale boxes which are a black outer with an inner square of grey going from 10IRE to 100IRE. If you have Avia or DVE (which may havwe the same windowed boxes but I don;t know), if you tried going from the 10IRE to 100IRE window you may see some changes in how the blacks look perhaps. ANSI would probably have an effect here too though, so it's not a perfect test but the first thing that came to mind.

    If I can think of a scene I'll mention it though (anyone else got any ideas?).

    Gary.
     
  30. The Nightfly

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    How about a scene with a lighthouse at night-time :devil:

    Rotating beam of light, intensity variations with a regular cycle. Should give a dynamic iris a bit of a work out.

    Allan
     

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