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Did I see rainbows?

Discussion in 'Projectors, Screens & Video Processors' started by MarkHudds, Dec 20, 2002.

  1. MarkHudds

    MarkHudds
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    Hi,

    Saw my first DLP projector yesterday - a Runco CL500.

    My main aim for the demo was to see if I get trouble with the rainbow effect before I jump for a new HD2 model.

    Did I see any? ... Well I think I did, only a couple on normal scenes. However when looking at scrolling credits and moving my head rapidly up and down when white text seemed to be multi-coloured.

    Admittedly I wouldn't watch a film constantly moving my head up and down but it did but a downer on what was otherwise a superb picture! I am used to LCD so the sharpness wasn't as good, however the blacks were a revelation.

    My question is does anyone know what type/speed of colour wheel is in the Runco CL500 (Runco don't seem to specify this!)

    Thanks.
     
  2. LV426

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    The circumstances you describe are exactly the type of circumstances in which the rainbow effect is most visible. It will also arise on a moving object where there is contrast - eg a dark foreground object moving across a light background.

    Whilst you say you wouldn't typically move your head around whilst watching, the truth is that, depending on the size of your screen and/or your distance from it, you might well need to pan your head during normal use, so as to, say, concentrate on something that is happening at one extreme edge of the picture, and then something else at the other edge (such as, two people talking over a coffee table).

    It's worth pointing out that peoples' visual acuities differ; some people have 'faster eyes' - ie. can see any type of refresh artefact more easily (and therefore intrusively) than others. I was actually conscious of rainbows at the Denon demo in Manchester in September - with two Barco CRTs!!
     
  3. gwbailey

    gwbailey
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    Well thank god for that Nigel I thought I was going crazy there for a minute... :D

    You see, I see them on all CRT's as well as all DLP's, so that just leaves LCD for me untill DLP's get sorted out!

    Regards,
     
  4. LV426

    LV426
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    Aha.... so I'm not alone.

    Like you, gwb, I am only comfortable when watching LCD projection and, right now, wouldn't go anywhere else - blacks or no blacks.
     
  5. MarkHudds

    MarkHudds
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    Can you explain how come you can get rainbows on CRT when there isn't a spinning wheel?

    Cheers
     
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    gwbailey, I'll have some if you're selling it ;)
     
  7. gwbailey

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    I know it sounds daft but it's true I swear!!!;)
     
  8. LV426

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    It's not the wheel, it's the fact that the picture is a sequence of coloured images which are supposed to blend together in your head.

    On a CRT, there are three tubes each producing one of the three primary colours.

    Now, if each tube's picture was produced at exactly the same time, there would be no issue. However, if each tube's picture is produced at a slighlty different time to the others, you have intermittent colour. Which causes rainbows for those of us that can see them.
     

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