RPTV - "The Circle of Light" - What is it?

Discussion in 'Displays' started by Bleddyn Williams, Aug 22, 2003.

  1. Bleddyn Williams

    Bleddyn Williams Supporting Actor

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    Bleddyn Williams
    I have a Pioneer 533 53" RPTV calibrated by our own Gregg Loewen. Despite some initial electronic problems, once the set was sorted out and then tweaked by Gregg, I have been enjoying the set a great deal.

    However, there is one thing I've slowly noticed that I don't remember seeing discussed elsewhere...

    When there is a patch of light on a dark/black background (like the disembodied heads at the start of Zardoz, or the highlighted figures on the new Chicago disc) then often a vague circle of light can be seen around the bright light source. I guess it would be about an 18" radius if it was a complete circle. The center of the "circle" is always the strong light source.

    Is this something I can adjust my setting to diminish, or is it an accepted consequence of RP? Given how fussy we are, I'm surprised I haven't read about this one before.

    All comments most welcome!
     
  2. Jack Briggs

    Jack Briggs Executive Producer

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    Nice film to cite in your description, Bleddyn! [​IMG]

    What you're noticing is called "spotlighting" (or "hot spotting"), and it's inherent to the RPTV concept (though the extent of the phenomenon varies greatly among all the sets out there). You are seeing the point where the three CRTs focus most of their light. Some of this can be reduced by minimizing internal reflections within the chassis. But you can't do away with it entirely.
     
  3. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    Nature of RPTV's given all that light reflecting in an internal box. No way to really address it short of covering up the mirror.

    Lens hoods and lining might help ... or might not.

    Regards
     
  4. Bleddyn Williams

    Bleddyn Williams Supporting Actor

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    Thanks for the feedback, gentlemen.

    When Gregg did my set, he did line the bottom of the enclosure (around the projection guns) with black felt. Doesn't sound like there's anything else to be done, then!

    Given how we dissect images here, I'm surprised that in the years I've read this forum I don't remember encountering this one before!

    Thanks again.[​IMG]
     
  5. Jack Briggs

    Jack Briggs Executive Producer

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    By the way, "Circle of Light" sounds like some Californian "New Age" drummers' circle or cult! [​IMG]
     
  6. Dave Poehlman

    Dave Poehlman Producer

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    AKA: Halos

    I've never been able to figure out exactly how they occur inside my set.

    I've read that building a hood to block stray light from the CRT's to the screen helps... also if you've got money burning in your pocket.. Duvetyne makes a good liner.

    I've noticed them too on my Toshiba. I've been waiting for my warranty to expire before I take the screen off to line the inside.
     
  7. Rich H

    Rich H Second Unit

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    I sympathize with this issue. Spotlighting has always been
    a source of frustration for me with RPTVs, even on the many ISF calibrated ones I've demoed. The Spotlighting leaves me the uncomfortable feeling I'm staring into the light of a projector pointed toward my eyes (which, I guess, I am). While I absolutely understand the appeal of RPTVs, and have seen images on them that are just sumptuous, the spotlighting and uneven illumination is distracting enough for me to be a deal breaker with that technology. I'm surprised I don't read more about this from RPTV owners.

    Rich.
     

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