what type of projection?

Discussion in 'Displays' started by John Roger, Oct 4, 2004.

  1. John Roger

    John Roger Stunt Coordinator

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    While looking through some RPTVs i came across LCD and DLP projection.Wonder why they are so expensive.What exactly are those?What is the advantage over CRT based?

    Are cheap plasmas worth considering?
     
  2. Steven_J

    Steven_J Auditioning

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    This is a common questoin along the forums, I had the problem myself not too long ago.

    DLP or digital light processing is used with a DMD chip, a lamp, and a color wheel. On the DMD chip, there are millions of mirros. They move when light is hitting it to on and off stages, facing, and facing away from the screen. Depending for how long they do this, and whether they're facing or away from the screen they show black, to many shades of gray, to white. The light then passes through a color wheel to display more than 16 million colors. If one wants to see the color purple for instance, light only reflects trhough the color wheel when blue or red light is falling on it, the eyes then combine these colors on the screen to see it.

    LCD or Liquid Crystal Display(Diode) has an effect known as screen door effect. I'm not sure too much on the technology behind it, i'm sorry for that, i'm new to the forums too, maybe someone else can help with that.

    -steve-
     
  3. John S

    John S Producer

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    The advanage of digital display, is these days, you can have a picture that never goes analog. You can do direct pixel mapping. This includes DLP, LCD, Plasma, both direct view and projection.


    The CRT is analog by nature.

    Cheap + Plasma = Oxymoron.. lol
    ED plasma while not ture HD, has it's place for sure. I'd rate DVD performance as quite outstanding on most of the ED Plasma displays I have seen.
     
  4. ChrisWiggles

    ChrisWiggles Producer

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    OK. You're correct. Your point?

    The way you stated that seems to very much imply that due to this fact, that digital displays will provide a better picture just "because it never goes analog." This is *completely* erroneous.

    For a decent comparison of these technologies that covers all the basics, please see this thread:

    http://www.hometheaterforum.com/htfo...t=DLP+LCD+LCOS

    It is still pretty up to date, except for the LCOS part. Projectors and TVs are out now with this technology, and at the very highest levels of displays, IMO this technology beats the DLP 3 chippers, subjectively speaking.

    However, some of the conclusions in that link are oversimplified, such as the "Because the mirrors on the DLP chip can be very close together, it does not have the “screen door” effect in LCD," which is absolutely not the case. DLP, as do all FP devices, suffer from SDE to dome degree, varying on pixel packing, resolution, and viewing angle. Even the 1080p sony Qualia has a viewable pixel grid at large viewing angles. From what I've seen only CRT projectors completely eliminate this problem at large viewing angles.
     
  5. John Roger

    John Roger Stunt Coordinator

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    Which one has got better picture quality?

    Some website advertised their LCD projection to have a "film projection like quality".

    That makes me wonder, what is the resolution of the film display in theaters?Is is just light passed through a film or any other technologies involved?
     
  6. John S

    John S Producer

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    No way Chris...

    I still way prefer CRT over any other.
    I was just try'n to really answer the question was all.


    So your answer Chris is there is no real advantage? That could be the correct answer. I don't think mine was incorrect at all. I really tried to nail down any advantage, this was the only one I could come up with is all. lol
     
  7. ChrisWiggles

    ChrisWiggles Producer

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    With digital projection, there is obviously the possibility of maintaining a digital signal the entire way, which is beneficial. But this gets you (usually) the best picture possible on that particular display. But this completely discounts the very different strengths (and weaknesses) of CRT displays, and of course you can't stay digital all the way, but that doesn't mean the picture won't stand up to an all-digital chain of course, as I too keep CRTs at the top of my subjective list.

    John Roger:
    Every projector seller will say theirs is the best.

    But from my experience, LCD is probably the furthest from the feel of film, due to horrible screen door. LCOS is probably the closest you'll get within digital projectors, and IMO CRT provides a picture that is probably most similar to film, but it still does have a different feel.

    As for the "resolution" of the film, this varies all over the map, and depends on the film stock, the quality of the print, how many generations away from the original it is, etc etc. Most film presentations are not as high-resolution as we'd like them to be, or that they could be.

    Some theaters are now beginning to employ professional DLP projectors instead of film, for some movies. I have not been satisfied with DLP in these applications yet, in equalling the better film presentations.
     
  8. John Roger

    John Roger Stunt Coordinator

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    DLPs don't have screen door effect.right?

    Are plasma displays a better option than projection?I want to consider plasma displays too because if one could afford LCD or LCOS projection why not go for plasma?
     
  9. ChrisWiggles

    ChrisWiggles Producer

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    Of course DLP's have SDE effect. That their pixel packing is a bit tighter than LCD means that it may be less visible at a particular viewing angle with a projector of the same resolution, but anyone who tells you that DLP doesn't have SDE is grossly mistaken.
     
  10. John S

    John S Producer

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    John Roger....

    With the ED displays comming down in price so much. I have suggested to many people to go just that way....

    If you have not demo'd a most modern revision of a plasma display. You should go check out some of the more recent Panasonics...


    Is 42" enough? Cause the 55"'rs are still mucho buckos... lol
     
  11. John Roger

    John Roger Stunt Coordinator

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    Are you sugesting i go for ED plasma than projection?
     
  12. John S

    John S Producer

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    John Roger, in some situations, I do suggest just that...

    If working lighting (light you cen read by) is to be used while viewing. Direct view plasma makes a ton of sense in that situation is all. Also if some of your seating is well off axis too.

    All projection is effected by to much ambient light.

    All rear projection is effected as you move off axis.
     
  13. Kin

    Kin Agent

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    CRT projectors give a great picture quality.... As long as you don't mind having to reconverge every once in a while. To answer your question way at the top.... LCD is a transmissive technology. This means the light is passed through it to create your image. This has hang ups, because the circuitry has to be somewhere, right? Around, in front, or behind the pixels. LCD puts the Circuitry around the pixels. This is why SDE is generally more pronounced with LCD.

    Plasma is great for a lighted room, because it creates it's own light source. The pixels tend to be a bit larger than DLP, though. It also hurts my eyes after watching it for a while, but that is pure preference....


    I would rather go DLP projector than plasma, myself. 92" diag screen for the same price as say a 42" plasma. Light control isn't that hard. Dark curtains (called blackout curtains) work great. You can generally get the material at JoAnne's for a relatively affordable price.
     
  14. John Roger

    John Roger Stunt Coordinator

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    one advantage i saw in rear projection is that if you play a DVD connected in component in total darkness, its a movie screen.Nothing can beat it! Especially if you have a 55+" widescreen.But when you watch normal channels RPTVs tend to look bad, plasma doesn't.Thats one thing that is making me sit on the fence.

    But i am not sure if it is due to the connections.The satellite reciever i currently got has only normal video connections(no s-video or component).Should i get a better one or an HDTV reciever?
     

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