Originally Posted by Robert2413
As a 141 owner, I've sometimes wondered this myself. I also see the lighter edges and darker center on completely black scenes (although the panel is no lighter than the night sky outside my window). Because the Kuros have been verified by measurement not to have "floating blacks," I suspect that the answer is that the deeper blacks in scenes that are not totally black are nothing more than the eye's adaptation to the brighter parts of the picture. But on the other hand, few people have the equipment to measure the 141's black levels accurately, so there might be a minor "floating black" issue that has not been detected. I dunno.
Regarding bias lighting, I have a bias light that I originally bought for the 150 that I had and sold when the 141 was available. With the 141, I find I prefer watching with the light off even at the expense of not seeing absolutely perfect blacks. I see too much of the room with the bias light on; it tends to take me away from the program material. YMMV.
I just wanted to add that the human eye can be finnicky about brightness and contrast in the dark. It takes the eye a while to adjust to darkness, and exposing the eye to any brightness at all will ruin its 'night vision' for quite a while. So if you are staring at a 'black' screen in a dark room, your eye will adjust and that 0.004 ft-L (right?) will look visible. But if there is say white text on the screen, suddenly that 0.004 ft-L seems much darker since the eye will lose some sensitivity in the lower range.
FWIW, I am making my own Bias Lighting setup using CREE LEDs with a dimmable potentiometer, I just need to order some elliptical optics to try out and make sure I can get the necessary spread at the distances I have. I want to be able to get a tighter light spread and dimming for exactly the reason Robert2413 stated: I don't want to see the room lit up, I just want enough brightness on the wall behind the TV to make the black look all black.