Bias Lighting for a 65" Display?

Discussion in 'Displays' started by Ronald Epstein, Jan 12, 2014.

  1. Ronald Epstein

    Ronald Epstein Administrator
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  2. Charles Smith

    Charles Smith Extremely Talented Member
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    Late to the party here, but a couple of cents worth of comment: I saw this thread and wondered what "bias lighting" was, initially assuming it was some high tech exotic thing that either wouldn't apply to me or would be so far beyond an ordinary person's budget as to be laughable. Well, I'm laughing (okay, smiling) with pleasure because I think it's basically what I discovered all by myself around 1989 and have refused to be without ever since.

    One day at the defunct discount store Caldor, I saw these "light canisters" that sat on a flat surface and basically looked like large white cans, kind of what recessed fixtures look like, but these weren't intended to be built into anything. I think they were five bucks apiece, and I immediately got the idea of what I'd do with them, and bought three. I placed them on the floor behind the TV (the Mitsubishi 25-inch "consumer monitor") and the two Vandersteen speakers, setting up a soft glow on the wall or shelves or whatever was behind them at any given time. Three regular incandescent 25-watt bulbs were just right. (I initially went for some color variety by using blue, red, and green bulbs. Those are a little too dim for anything but a plain white wall.)

    I don't have anything sophisticated or expensive going on here, lighting-wise, but I somehow became crazy about soft indirect lighting several years before finding these, and they fit right into my scheme for keeping rooms attractive while being gentle and easy on the eyes. I'd actually love to do more with that idea than I do.

    Anyhoo, these three "upside-down lamps" made an immediate and dramatic improvement in the quality of the TV/movie watching, and in the feel of the room. I don't know how this would measure up to any recommended viewing specs, and maybe someday I'll try one of these things expressly designed for the purpose, but for now you'll just have to pry these out of my cold dead hands. I can't even believe there'd be any controversy over suggesting or trying or using such a thing. Everyone who's ever walked into my music/movie room has instantly loved the "feel" of the room and the quality of the display, throughout the years with the CRT TV and now with the plasma. A few people (but not all; some folks don't really notice anything) commented on how nicely I'd controlled the lighting, and how that added to the comfort of viewing.

    So, yes -- back-lighting for direct view displays and none for front projection (just like in a theater) (duh). I've known this for years without having received professional advice on the matter all of that time. Glad to receive it now, though! :)
     
  3. Ronald Epstein

    Ronald Epstein Administrator
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    Charles,

    What a great read.

    You brought up a good point about ambiance. I was initially more interested in the
    improved ambiance that the "glow" behind my display would bring to the room.

    Just to improve my office, I am buying ambient lighting for behind my computer
    monitor, to give it a nice blue glow. I hear that it greatly reduces computer eye
    strain in darker rooms.

    I really think this bias lighting is going to improve my home theater. If anything, it's
    going to improve the "feel" of the room.
     
  4. Gregg Loewen

    Gregg Loewen Video Standards Instructor, THX Ltd.
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  5. Ronald Epstein

    Ronald Epstein Administrator
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    I realized I never followed up on this conversation.

    So....I got bias lighting for my 64" Samsung display.

    Ended up buying two sets of these.

    They have a self-adhesive backing, though I found that it wasn't strong enough
    to keep the strip from slipping. I ended up having to support it with electrical tape.

    Each set has a USB plug. This was great for plugging directly into my display so that
    the LED strips turn on and off with the television power.

    The verdict?Noticeable improvement.

    First, it does help eliminate eye fatigue. Secondly, due to the ambient lighting,
    one does get the perception of deeper black levels.

    I find myself watching normal broadcast television with the lighting, while still
    preferring to go totally dark on movies --- only because I feel that is the proper
    way they should be seen.

    bias1.jpg

    bias2.jpg

    I realize not everyone will be onboard for adding bias lighting to their display
    setup, but I am here to tell you as a total newbie to this kind of thing that it does
    seem to enhance the viewing experience. Best of all, it's the kind of improvement
    that isn't expensive.
     
  6. DaveF

    DaveF Moderator
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    Nice! I'm so out of date, I still thought in terms if a fluorescent bulb on the floor behind a CRT. :) I never thought about a USB-powered led strip. I've added that to my amazon list for future purchase. How did you pick two strips?
     
  7. Ronald Epstein

    Ronald Epstein Administrator
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    Dave,

    Somewhere in the Amazon reviews it indicates that one strip is generally
    good for (I believe) up to a 54" display.

    Someone chimed back that he picked up two strips for his 65"

    In any case, it doesn't seem to be overbearing to have two strips for a 65" display.

    In fact, it seems just about right.
     
  8. GeorgeAB

    GeorgeAB Second Unit

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    Find out what the color temperature and color rendering index is before purchasing any bias light. The correlated color temp (CCT) should be 6500K, and the color rendering index (CRI) should be 90 or higher. "White" LEDs are notorious for being too blue, with also poor CRI ratings of 70 to 80. If the source does not tell you either figure, they may either have no idea or may purposely hide poor ratings.

    Lighting products made in China are notorious for using false claims for color performance. I was recently negotiating with one of the Amazon vendors to develop an LED bias light that met video standards. The best CRI they could come up with was less than 79.

    Best regards and beautiful pictures,
    G. Alan Brown, President
    CinemaQuest, Inc.
    A Lion AV Consultants affiliate

    "Advancing the art and science of electronic imaging"
     
  9. DaveF

    DaveF Moderator
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    George, are there LED strips that come close to 6500K with good CRI? I had some simple bias lighting years ago with a 36" CRT, using a fluorescent. It was difficult to get broad diffuse illumination with that. These LED strips look like they are much easier to mount and get light where it's wanted, uniformly around the TV. And that easy broad scatter could outweigh imperfect color temperature.
     
  10. GeorgeAB

    GeorgeAB Second Unit

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    I have yet to find an LED product with both the right white point and sufficient CRI. My company has been working with a string of suppliers for several years and none has yet to deliver the right combination. There are options on the market for folks with compromised wall colors that could suffice under casual conditions. Nothing in LED would be more diffuse than a fluorescent tube, since it is coated continuously inside the glass with phosphor. If the LEDs are spaced too far apart, a close proximity to the wall (such as with a low profile wall mount) will result in a spotty pattern of illumination. If enough distance is provided from the wall, the illumination can blend better.

    One problem with LEDs is their relatively narrow beam pattern. Some strips shine straight into the wall behind when attached to the back of the TV. Wall mounted panels can end up with not enough illumination shining outward, away from the edge of the TV. Wall mounted TVs often suffer from multiple complications and compromises. I try to talk my clients out of hanging their TV on the wall, unless there are unusual circumstances that make it a legitimate option.

    The pattern of how the illumination appears on the wall may be an aesthetic concern for some people. Video bias lighting is not intended to be a decorator feature, but an enhancement to the viewing experience of the image on the screen. Unfortunately, many people's first exposure to the technique is how it looks in the room. Some think it's a "cool" addition to the room. That's the last item of importance in a video system, if image quality and viewing comfort are the priority.

    Looking "cool" may be a sufficient priority for some home theater owners. We each get to decide what our lifestyle priorities are. Personally and professionally, I have chosen to focus on what delivers the best image quality from a video system. That priority is easily obtainable for the widest portion of the populace if proven imaging science principles and display industry standards and best practices are followed. "Imperfect color," as you suggest, would not override how the bias lighting looked in the room for that type of approach.

    Each viewer gets to decide what they do with their system design. My company is dedicated to advancing the art and science of electronic imaging. I teach and advocate for the best sound and image performance, not compromises that result in diminished or distorted performance for the sake of individual whim, fads, or fleeting fashion. As Joe Kane persists in saying, "It's all about the art." Faithful reproduction of video programs relies upon following industry standards and practices.
     

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