DLP rainbows

Discussion in 'Displays' started by craigDeguz, Sep 2, 2005.

  1. craigDeguz

    craigDeguz Auditioning

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    Hello all,

    I was looking at some dlps today (samsung, toshiba, mitsubishi) and i was trying to look for the so called rainbow effect. To tell you the truth, i cant see it at all. What am I looking for with the rainbow effect? I was almost trying to find something but couldnt. could someone tell me what exactly it is and how to find it because i am thinking about getting dlp.

    thanks
     
  2. Leo Kerr

    Leo Kerr Screenwriter

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    Rainbow effect is caused by the rapid sequential display of colors to build up a "composite" color image. In the most simple form, the projector takes each frame and flashes it on the screen three times: red, green, and blue. More complicated ones do two or three sequences, and/or add in a white frame (works great for projecting Windows interfaces. Gives you serious power and contrast. Iffy for video.)

    The easiest way to see it is to, for example, track a fast-moving object against a static background, where your eyes are doing the moving.

    High contrast and/or black-and-white imagry is also said to be good at 'breaking' the system.

    I find that walking past a display without really looking at it (as in, periferal vision) is also a good way to 'break' the image.

    If you're lucky, you won't be able to break the image.

    Leo
     
  3. Kevin C Brown

    Kevin C Brown Producer

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    Yes, some people are more sensitive to it than others.
     
  4. Paul Seyfarth

    Paul Seyfarth Stunt Coordinator

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    Also even if you do see it at first, over time you will see it less and less. Heck after a couple years I bet it would be hard to get your eyes to see rainbows.

    If you can't see them now thats great you shouldn't worry about them. Now you might see one flash of one every once in a while but it's going to be so small of a time.

    When I first got my x1 I could see rainbows quite a few times( really depending on the movie and scene I was watching). But I have had it for a couple years now, and I don't remember the last one I saw.
     
  5. Leo Kerr

    Leo Kerr Screenwriter

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    It's good to know that you can be trained not to see them; most people I know have been the other way - trained to see them. But then I hang with a bunch of serious tech critics... at trade shows, camera and projector people hate to see us coming...

    Leo
     
  6. Kevin C Brown

    Kevin C Brown Producer

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    Again, person dependent. I have come across half a dozen people, who once they knew what to look for, couldn't get used to them no matter what. A lot like the chroma bug that players used to have. If you didn't know what to look for, you were golden. But once you know, you had to get rid of the player. Becomes a distraction to the picture itself.

    By the way, each of those people eventually got rid of their DLP sets and went with LCD rear projection or a plasma.

    Newer DLP sets are better in this regard though. They have the color wheel rotating faster.
     
  7. Paul Seyfarth

    Paul Seyfarth Stunt Coordinator

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    yeah, I knew exactly what to look for as when I first got mine. I heard all about those rainbows on these forums. They were quite annoying when i first got the projector, then less annoying( I could still see them but didn't bother me much) to the point now where it's actually hard to make my eyes see them any more. I was still seeing rainbows for quite a long time I would guess about a year, then sometime after that stoped.
     
  8. Todd Beachler

    Todd Beachler Stunt Coordinator

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    I saw a rainbow once in BB on a Sammy. I don't remember the circumstances. I now own a Sammy, but haven't seen them at all. Some see them, some don't. Good luck! [​IMG] [​IMG]
     
  9. Eric Samonte

    Eric Samonte Screenwriter

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    I think there was a thread here with a kind of a poll on who can and who can't see rainbows. It turns out if ur an avid gamer, u would be more susceptible to them. I had the X1 before and had rainbows that I had to return it. I even saw them in the 2nd generation Sammy DLPs but not the recent ones even if I try really hard.
    So, if u can't see them now, u shouldn't worry about it. You are good to go dude!
     
  10. Thomas_A

    Thomas_A Second Unit

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    i often wonder...If no one had ever mentioned Rainbows...would folks still see them?
     
  11. Bob_L

    Bob_L Supporting Actor

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    Of course. How do you suppose we found out about rainbows? Texas Instruments certainly didn't bring our attention to them before DLP-based color-wheel imagers were released.
     
  12. skip marr

    skip marr Stunt Coordinator

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    Is the "rainbow effect" prevelant in projectors, or just the projection units?

    Thanks.
     
  13. John S

    John S Producer

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    You know rainbows are just an odd beast....

    Take the Infocus 4805, I installed one for a friend. and for the most part I don't see them, but in any given viewing if I start seeing them, I see them for the rest of that viewing. Then the next time I come over the same thing again. Just really odd.
     
  14. Leo Kerr

    Leo Kerr Screenwriter

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    Rainbows are potentially visible in any single-chip DLP display unit.

    It's a fact of life with color wheels.

    I admit, I find it harder to see on RP DLPs rather than FP DLPs.

    Leo
     
  15. Jack Ferry

    Jack Ferry Stunt Coordinator

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    Like many, many others, I saw them at first on my 4805, now I can't see them even if I try. I have never once had a guest or family member mention seeing them, or complain of headaches after watching a movie.
     
  16. Steve Schaffer

    Steve Schaffer Producer

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    It's most noticeable when your eyes move rapidly, especially if not focused on the screen. One scenario would be if you were eating dinner in front of the set--when you glance down at your plate you may see the rainbows. I had an Hitachi crt set that would make me see green flashes in the same scenario.

    Some peoples' eyes have a very slight constant involuntary movement, called nystagmus, which while not even noticeable to them will caue the rainbow effect on a dlp set to be especially noticeable.
     
  17. Kris_M

    Kris_M Auditioning

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    my .02 is.... My first projector was a single chip DLP. Benq 6100. At first it was great, after about one month I started to see the rainbows. After 2 month I could not watch an entire movie without getting a headache. After 3 months I had to get rid of it and went to first a Boxlight HD-1 and now have a Sanyo Z2. I may be hypersensitive to projector rainbows but havent noticed them in the BB or futureshop DLP TV's. But on the projector I could not tolerate it. YMMV

    Kris
     

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