Question about CRTs and black levels

[Howard]

Theoretically, the phosphors that aren't hit by the beam don't illuminate, right? So why is it that the "black" pixels aren't black, but almost black? This effect is especially noticeable if you look at the edges of the screen; there's the very black border between the bezel and the viewing area, and the thin line of almost-black inside the viewing area that borders the displayed image (browser window or what have you).

 

[CP5670]

This depends on the particular CRT model (only some of them look like that), but I believe it's caused by the phosphors reacting to external ambient light. In most cases, you can get rid of that effect by just reducing the amount of light in the room.

 

[Howard]

I was thinking of that, but I turned off the lights (at night, in my basement) and it was still visible.

 

[bobsmith1492]

Stray electrons in the tube strike the screen in random locations causing the entire screen to glow faintly while operating; also the screen will absorb some ambient light, so, even when turned off, CRT tubes can glow faintly after being exposed to light.

 

[SonicIce]

It's true that some models are differant than others. My dads Dell P992 is very grey even with brightness at 0 while the outside border remains black, while my NEC FE1250+ is very close to being as black as the outside border.

 

[dug777]

As has been said, light scatter from other beam would be the main culprit i guess. My 21" Samsung is excellent with regards to black levels tho.

 

[Hadsus]

The best I've seen with blacks is.......my CRT! Not a glass faced one but a rear projection Pioneer Elite 53" CRT with a plastic lenticular screen. It reflects nothing and when you turn the lights off it really is black if calibrated properly. It was pretty cool to plop on a good DVD with fine gradations of black because it added so much to the film. No banding, no blueish blacks, just incredible shading. These days, thought, the guns have gotten a bit worn and it doesn't perform as well as it used to. I like my plasma and LCD just fine but blacks are still owned by rear projection CRTs.

 

[JRW]

My Sony XBR960 CRT HDTV has the deepest blacks ive seen on any TV period (even other CRTs) If im watching a movie at night and the screen fades to black you literally cant tell the TV is on, not even a hint of light comes out of the screen lol , This does wonders for the picture quality when playing games / watching movies at night. My PC FW900 CRT is very close but not quite pitch black, and on the othe hand my NEC 20WMGX2 LCD struggles to display black at night , its more of a medium gray at best.