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Backdoor effect?

Discussion in 'Projectors, Screens & Video Processors' started by Paulherb, Jan 14, 2002.

  1. Paulherb

    Paulherb
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    Is the "Backdoor Effect" which i've heard so much about on the American forums the same thing that us brits reffer to as Chicken wire effect.

    Any help would be most welcome.


    Cheers


    Paulh.
     
  2. nigel_williams

    nigel_williams
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    I think you mean "screendoor effect" i.e. if you sit too close to an LCD screen display you can see individual pixels (and the gaps between them).
     
  3. Mr.D

    Mr.D
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    Screen door effect is the visibility of the gaps between the pixels : looks like a mesh.

    I think " Backdoor Effect" is something that happens in the showers in prison. Shawshank Redemption is a good demo disc for this.
     
  4. Rob

    Rob
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    LOL :D

    Screen door can be very noticeable on some PJs. I've noticed it more on DLPs, although they're supposed to be better than LCDs. On a friends DLP, its very noticeable (to me) sitting at around 14 feet away.
     
  5. chicken balti

    chicken balti
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    I bought a dvd player from Techtronics that turned out to be faulty. When I sent it back I got severe 'backdoor effect'.
     
  6. Paulherb

    Paulherb
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    Thanks for advice Gents

    Paulh.
     
  7. Tempest

    Tempest
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    14 Feet away :eek:
    Does he lend you his binoculars when he shows a film or do you bring your own.
    And how the hell can you see pixels from that distance ?
    Think I need to visit your optitions and have the same zoom lenses fitted to my eyes :D
     
  8. nickane

    nickane
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    LOL indeed.

    It is my understanding that the screen door effect is what happens when you can see pixels and the gaps between them on a panel pj whose pixels are in grid form (as almost all modern pjs are).

    The chicken wire effect is exactly the same except it occurs on pjs whose pixels are placed in a honeycomb formation: ie

    /\/\/\/\/\/\
    | | | | | | |
    /\/\/\/\/\/\/\
    | | | | | | | |
    \/\/\/\/\/\/\/
    | | | | | | |
    /\/\/\/\/\/\/\

    Most current pjs have SVGA/XGA res, so this formation is rather rare, but it is used in cheap panels, creating a viable image (barely) with less pixels. Horizontal res is passable, but vertical res is shoddy (as pixels are far longer than they are wide.

    And that's why there are two different names for this effect, as for the backdoor effect, I would rather not explain what this entails, as I might then suffer the wrath of the moderators, but I imagine there are other forums where members would be happy to give you a hand.
     
  9. Rob

    Rob
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    You don't need binoculars to see screen door at normal viewing distances on some projectors. The projector I saw was a Davis DL450. Watching the opening scene to Tomorrow never dies, I became aware of a faint black grid everytime there was an explosion (most of the time). I wasn't looking for it, I had never heard of screen door at that point. It was only some time later I found out what it was and why it was there.

    Rob.
     
  10. Roland @ B4

    Roland @ B4
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    No No its a medium sized black bird.
     
  11. Jeff

    Jeff
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    I have seen the back door effect, I noticed someting not quite right on the end credits of a DVD. It was light bouncing back off my ISCO lens, hitting the back door and bouncing back on to the screen. :D
     
  12. Chris Frost

    Chris Frost
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    Isn't that a Jackdaw, Roland?
     

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