Lighting in back of TV for watching movies?

Discussion in 'Archived Threads 2001-2004' started by scott_tinari, Oct 11, 2001.

  1. scott_tinari

    scott_tinari Stunt Coordinator

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    What is the purpose of having light in back of your tv when watching movies. Where do i get this light. Can someone help
     
  2. Kevin C Brown

    Kevin C Brown Producer

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    Scott- Hopefully others will chime in with a little more info, but this what I read a while back.
    You want a 15W incandescent bulb running behind the set.
    The reason why, is that the light from a TV is not enough to open up all the cones on your retina (or something).
    So the 15W lamp helps to do that. Gets you a better picture to your brain! [​IMG]
    (Me, I use a dimmable halogen lamp off to the side, turned all the way down.)
    I have seen posts of places to buy specific lamps/light bulbs for this purpose. There are differences in terms of the "color" of the light that you're supposed to use.
    But some light is probably better than none at all.
    ------------------
     
  3. John H

    John H Second Unit

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  4. Jeremy Anderson

    Jeremy Anderson Screenwriter

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    The reason behind this is that backlighting helps with eyestrain and color detail. In a theater, you don't experience these problems because so much of your field of vision is lit. But in a home theater with all the lights off, you'll notice that a completely dark room will eventually start to hurt your eyes.
    I thought this was all a load of crap... until out of curiosity, I picked up an $8 flourescent fixture and a $3 daylight bulb from my local hardware store. It really does make a HUGE difference in your perception of color on the screen. I had to change my television's calibration a bit with the backlight on, but it really does make a dramatic change. And now I can watch 3 movies back to back and not get any eyestrain. An added bonus is that I don't get sleepy as quickly when watching late-night movies.
    Things to note: It is important to have a white or gray wall behind your television for this. It is also important to get a bulb that is as close to daylight rating as possible. These are sometimes referred to as grow-lights, but my local Home Depot had them as "Daylight Bulbs". The Avia Guide To Home Theater calibration disc has a section on backlighting and the proper gray level for home use, if that helps you at all.
     
  5. Eliab

    Eliab Agent

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    Hi there,
    In regards to CinemaQuest's Ideal-Lume bias light, the ideal (no pun intended) location would be on the back wall directly behind your TV, with the light facing the back of the set and positioned parallel to the middle of the screen. The goal is to create a diffused low ambient D6500 light emanating evenly from the sides and top of the TV. This extra light is essentially taking the place of the light that would normally fill our peripheral vision coming off of a large movie theater screen (hence the reason why they aren’t used behind screens larger than 6’). The benefits are prolonged viewing without eye-fatigue and an improved sense of depth to the image. And, for people who prefer to view their TVs with some room lighting, the Ideal-Lume’s placement will not cause nasty reflections (on DVTVs and RPTVs with glare screens), and will also not washout a display devices image the way normal lighting does.
    When preparing the Ideal-Lume, I like to remove the aluminum backing behind the fluorescent bulb. I find that it helps in creating a softer more diffused light. I also utilize CinemaQuest’s dimmer pack ($12.95), which is basically a plastic tube with two light reducing filters. The fluorescent bulb then slips into this plastic tube thus reducing the intensity of the light (my clients and I usually prefer using both filters within the plastic tube). Good Luck!
    Eliab [​IMG]
    ------------------
    Avical
    ISF Certified Calibrations
    www.Avical.com [email protected]
     
  6. Guy Kuo

    Guy Kuo Supporting Actor

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    A bias light is a definite step in the right direction. The Idealume's bulb gives just the right color of white, something a regular bulb can't deliver without filtering.
    One neat thing to do is arrange for the bias light to come on automatically when the TV turns on. Sears has a "switch" in their shop tools section
    (www.sears.com and search for product # 00924031000)
    which lets you plug in the TV in the master outlet. When the "switch" sees the TV power drain go up, the slave outlets power up. The switch units do vary in their senstivity. You may need to try more than one unit to get one which responds correctly to your TV's power load. Sears has a pretty reasonable exchange policy.
    ------------------
    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
    [Edited last by Guy Kuo on October 11, 2001 at 04:40 PM]
     
  7. Paul Hives

    Paul Hives Auditioning

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    I too was skeptical until I tried it. Now I can't imagine watching the set with out it. It's hard to quantify but it really does work.
    I bought a cheap 18" fixture from ACE hardware and velcro'd it to the back of my TV. I have a dark green wall behind the set and the ligt makes the whole thing look really cool.
    One note of caution on the so called daylight bulbs. I bought one home and we checked the temp with the analyzer. It was somewhere around 2500K.
    The bulb must say 6500k. BTW, I finally found them at the PetSmart. It turns out that aquariums use them a lot.
     
  8. SteveBjr

    SteveBjr Stunt Coordinator

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    Can anyone recommend a good light that sits behind a TV for this purpose? I guess a nightlight could work but does anyone know of a specific light actually made for this?
    EDIT:
    Err nevermind i just saw the link for the question i was asking.
    ------------------
    Steve,
    DVD Collection
    [Edited last by SteveBjr on October 12, 2001 at 09:14 PM]
     
  9. Guy Kuo

    Guy Kuo Supporting Actor

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    The correlated color temp of a bulb being 6500K still doesn't ensure you have the right color of light. That's something practically no one bothers to explain. It's tough enough just getting the idea of color temperature across. Having to then say that's only a simplified version of the story would scare off most readers.
    Color can be though of in terms of the amount of redness, greeness and, blueness. In the CIE color system these are represented as x, y, and z. Any color saturation, hue, and brightness can be specified as an xyz coordinate. You can also express it color as xy and capital Y which is the luminance. This isolates the coloration from brightness and lets you deal strictly with color as a too dimensional xy coordinate. The slice at the widest visual color plane is the one you often see as the CIE color chart.
    A black body emits light which can be represented on that plane as the black body line. That primarily runs in the red-green direction. What we aim for in video is a specific point known as D65. It's very near the 6500 Kelvin point of the black body curve.
    The "correlated" in correlated color temperature means that the stated color temp is the closest point on the black body curve from the color that the bulbs outputs. Since the point can be some some distance off the black body line, there are colors which are plus or minus the correct amount of green which still get reported as 6500K. Basically we're after a specific point in a 2 dimensional XY color coordinate system but color temperature is only a one dimensional expression giving a position along a curve in the plane. Things which are off the line get reported as a CCT but you don't know how far off the line the color actually is when you only know the CCT. So you find a lot of "D" type bulbs which are actually too greenish and a lot of aquarium and pet bulbs which are too magenta (too little green). The Chromalux 1XX bulb in the above mentioned IdealLume gets the closest to hitting D65. Unfortunately, that German made bulb is hard to find.
    BTW, what did you measure the CCT of the bulb with? Virtually all tristimulus meters read incorrectly when measuring fluorescent bulbs due to the very narrow emission lines of the bulbs. A spectroradiometer is more likely to read the CCT of fluorescent bulbs correctly. Regular old tristimulus analyzers read way off the mark for non-CRT light sources.
    True enough the color of the wall will throw things off, but doesn't it make sense to get at least one reference that shows the correct color of white so you can more readily tell how far off your display is?
    [Edited last by Guy Kuo on October 12, 2001 at 10:01 PM]
     
  10. AllenBF

    AllenBF Auditioning

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    An update for building a Home Depot 6500K light unit.

    Because I was not sure if back lighting my new 51' Hitachi would have any benefit for me. I didn't want to spend a lot of money on a prototype unit. So I thought I'd give the Home Depot(HD)design a shot. I wanted to build a 24" device but at both HD and Lowe's the only 24" bulbs in the 6500K range were 6000K grow lights (take another hit). But HD did have:

    1. Daylight Philips bulbs at 6500K - 85 CFI - 48" in a 2- pak for $5.50.

    2. A 48" garage light fixture with cord in white for $7.75

    3. A can of flat black spray paint for $2.00.

    My only fear was that, with even only one tube in the 48" fixture the back lighting would be too bright. So I started looking around for something to cover up part of the tube. What I found in the HD Heating Duct aisle were 6 foot X 3/4" plastic foam insulation tubes for water pipes $2.00. The tubes are cut down one side so you could slip it over a water pipe(6500K bulb).

    I went home and painted the fixture flat black to match my Hit. I then cut the foam tube into 4x1' and 1x2'lenghts.

    Last night I tried one bulb with a 1'piece of tube over each end of the bulb, giving me 24" of exposed bulb,and it worked great. I think tonight I'll try a few more configurations, with the other bulb and the rest of the foam(always got to tweek that's why I love High Def.).

    When I get it right I'll attach the light unit to the back of the set with some heavy duty velcro/self adhesive back/ tape I found at my local fabric store. Which gets me to thinking "maybe for the 'how do I clean the screen of my HDTV' thread maybe I could sew............hehe."
     
  11. Jan Strnad

    Jan Strnad Screenwriter

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    I went the Home Depot route, too. Bought an 18" GE fluorescent fixture that came with a 6500k bulb. $8 plus tax.

    My 42" Tosh sits in a bay window. I placed the light fixture on the window sill.

    Works great. I'm sure that 6500k bulb temperature is off, but the unit does make a difference when watching at night. And for $8...darned cheap tweak.

    (I like the sound of that Sears switch, though!)

    Jan
     
  12. GeorgeAB

    GeorgeAB Second Unit

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    Location:
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    Real Name:
    G. Alan Brown
    For Guy Kuo,
    The Ideal-Lume Pro by CinemaQuest, Inc. was measured by GretagMacbeth (world leader in color standards) with their LightSpex spectroradiometer. Fluorescent fixtures affect the performance of the bulb placed in them. If the type of ballast does not illuminate the phosphors efficiently it can alter the spectral output. GretagMacbeth's D65 bulb is the most accurate daylight fluorescent in the world. The x/y coordinates of the Ideal-Lume Pro sample were: 0.3133 on the x axis and 0.3276 on the y. Correlated Color Temperature (CCT) was measured at 6476 Kelvins.
    As you know, the D65 point on the 1931 CIE Chromaticity Diagram is at the following coordinates: x - 0.3127 and y - 0.3291. The practical tolerance of deviation from the ideal allowed in the professional video arena for display calibration is +/- .004 along the x and y direction. The measured sample of the Pro only deviates by: +.0018 along the x direction and -.0012 along the y!
    "Color Rendering Index" (CRI) is a crude averaging of the spectral performance of an illuminant. "Spectral Power Distribution" (SPD) is a much more accurate and thorough analysis. CRI is used in the commercial and consumer lighting industries because it is a simple quantifier, a single number. SPD readings are very complex and must really be communicated via a spectrograph. Most commercial fluorescents use three or four phosphors and have dramatically erratic SPD curves. The GretagMacbeth bulb used in the Ideal-Lume Pro incorporates a patented seven-phosphor formula and has the most accurate SPD performance available.
    Viewing environment conditions are every bit as important to the real-world performance of video displays as listening environment conditions (room acoustics, speaker placement, etc.) are to the performance of sound systems. Much is appearing in the home theater press these days pertaining to the affect the room has on sound. Very little is discussed in the area of viewing environment principles. In the professional arena these principles are much better known and habitually incorporated in video production and monitoring environments.
    For additional detail pertaining to "the ideal viewing environment" consult: www.cinemaquestinc.com .
    Best regards and beautiful pictures,
    G. Alan Brown
    Insist on HDTV![​IMG]
     

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