Backlighting for RPTV?

Discussion in 'Archived Threads 2001-2004' started by Max Knight, Oct 18, 2001.

  1. Max Knight

    Max Knight Supporting Actor

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    [NOTE: I posted this in Building a Home Theater, but didn't get a response]
    I've recently installed a 6500K backlight behind my 40H80. It seemed a bit bright reflecting off the white wall, so I stuck a few sheets of black matt above and below it which has helped a lot.
    So far I like it, it provides enough light in the room that I'm not going to knock over a glass, but doesn't wash out the picture.
    A question for others with backlights:
    How much light is good? Should I be looking for a gentle glow just around the screen, or a little more? What are some good ways to dim the light a bit without sacrificing the color qualities?
    Thanks,
    Max
     
  2. Guy Kuo

    Guy Kuo Supporting Actor

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    5 to 10% of the peak white intensity is recommended for the back light. The AVIA DVD has a pattern which shows the correct luminance level. If your light matches that pattern in intensity, you're in range. Since the brightness of the pattern automatically goes up and down as you adjust contrast and black level, the pattern self corrects for the settings you are using.
    I believe VE has a similar pattern, but only showing a single intensity rather than the top and bottom of the range.
    ------------------
    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
     
  3. Max Knight

    Max Knight Supporting Actor

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    Thanks Guy! I'll give that a check tonight. Any suggestions on how to dim the light should I be over?
    By the way, I've enjoyed your posts in the Tivo forum over on AVS. I'm an avid Tivo user and evangelist!
    -Max
     
  4. Guy Kuo

    Guy Kuo Supporting Actor

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    Your use of black masking to block part of the lighting is fine so long as you don't occlude ventilation for the lamp. Another method is to visit a theater supply store (live theater I mean) and obtain some neutral density lighting filter sheets. They'll have them in pretty good size sheets from manufacturers such as Rosco and Lee. While you are there pick up some swatch books for the color filter lines. The swatch books come in handy for picking out a filter color and are often free of charge.
    Anyway, add the neutral density filter in layers to reach the brightness level you want. A 25% density sheet should give you plenty of attenuation as you increase the thickness. You can also get a lower attenuation and use more layers. That will give you finer control. Just be sure to leave enough room for ventilation!
    And yes..... TV without TiVo is impossible to conceive after a TiVo is installed. It's hard to get people to get one, but once they have it for a week, trying to take away the TiVo would be like taking away someone's 100 inch screen and sending them back to a 19 inch black and white TV.
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    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
    [Edited last by Guy Kuo on October 19, 2001 at 09:02 PM]
     

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