Axiom Home Page Forums General Discussion Home Theater Bias Light

Philips offered that....

It was Phillips, and they called it Ambilight. And you're right, they missed the point. The color and intensity varied with what was on screen. So it couldn't provide a reference at all.

Very interesting, Chris. Thank you so much.

We have a 61" JVC HD-ILA RPTV. We always have some ambient light on in the back of the room; it helps a lot. Since the lights are small, halogen pucks firing at the white, cathedral ceiling, there is no glare on the TV.

I'm curious about how the color of the wall behind the TV might affect this concept. Painting the interior of our house is slowly working its way up the list, and I had been thinking of going "dark" behind the TV, but your post is making me rethink that.

SO.....if we just went standard, are we talking 25w, 40w, 60w....?

1.21 Gigawatts.

You don't want an incandescent bulb for this. Their color temp is way too low, it'll bias your eyes to make everything appear blue on the screen. You need a "daylight" bulb, the closer to 6500K (which is what the color temp of your display should be set to also) the better.

As for lumens, it varies based on the distance to the wall. If you have any DVD/BD with test patterns look at the 15% gray, that's how bright the wall should appear behind the TV. That is one nice thing about the Ideal-Lume Pro, it has a dimmer so I could dial it in exactly. Is that worth the 500% increase in price over the standard? No.

Excuse my ignorance - so would one of the Fluorescent bulbs - low wattage (for lack of a better term) in one of the configs like "Daylight" aiming at 6500K is what I am getting out of this?

There's two things which determine the quality of a light source that's claiming to be "daylight". First the color temp, daylight falls in the 6500K range, and that's exactly the number you want for a video display. The other is CRI (Color Rendition Index), the sun gets a CRI of 100, because that's the reference. It's basically a measure of how complete the spectrum produced by the bulb is. Good bulbs are just above 90, excellent in the mid-90s, and crazy expensive in the high-90s.

If you can find a low-lumen, fluorescent bulb with a color temp of 6500K, and a CRI over 90, you'd be in good shape. If you just want to get an idea of what the light would bring to your display, go with any daylight CFL. But at $60 for a 10,000 hour bulb, plus fixture, the Ideal-Lume Standard is a great deal.

Thanks. I knew I would learn something today - did not know about the CRI..........Rob

The problem with using an excited phosphorescent material for a light source is that it isn't black-body radiation, but rather conforms to a more coherent spectrum. So florescent lights trying to mimic white light will use several different materials in the coating, each with a different spectral center. The overlapping spectra produce something closer to "white" light.

Cheap bulbs will use 2 or 3 phosphors and produce a very poor, tinted light (sub 90 CRI). At 5 different phosphors florescent bulbs take on a different character and become very high quality light sources (94+ CRI). At 7 (96 CRI), they best everything but the $1500 filtered tungsten halogen-cycle bulbs.