Contrast Ratio-what's the typical contrast ratio for a CRT??

[PremiumG]

Contrast Ratio-what's the typical contrast ratio for a CRT??

 

[unfalliblekrutch]

i believe it's basically infinity because CRTs don't have backlighting.

 

[kmmatney]

Depends how old the CRT is - they change (for the worse) over time. I once read that a typical CRT has a contrast ratio of 700:1. I think good ones can be a lot higher though. The contrast ratio o the last CRT I owned was "crap:1".

 

[xtknight]

Probably 2000:1 for a decent shadow mask, or 11000:1 for the best aperture grille CRT (Iiyama IIRC).

 

[PremiumG]

wow, so a plasma can have better ratio than a CRT??

cause i've seen plasmas with 15,000:1 ratio.

I also doubt a CRT can be infinite because no matter what, there is going to be some light behind each black pixel (maybe from a nearby pixel or what not)

 

[zephyrprime]

I've read that the contrast ratio of CRTs is about 700.

In reality, the contrast ratio on crt monitors is rather poor. In a real world room, the contrast ratio of a tv can be ~100. http://www.poynton.com/notes/Timo/Weber_and_contrast_ratio.html
A crt produces it's electrons from a vacuum tube which itself is a descendant of a light bulb. Due to capacitance and leakage current in transistors there will be a weak beam emitted even when the beam is supposed to be turned off. Also, there is some charge on the screen itself from previous frames. This limits the contrast ratio of a CRT. However, the is another issue with the published contrast ratios for a TV being less realistic than for a LCD. As a TV ages, it will suffer higher and higher leakage current but contrast ratio measurements are always made with a brand new TV of course.

The worst thing for CRTs is white washing due to ambient light. The phosphors on a crt are much more reflective than the surface of a LCD which only has color filters. Also, LCDs need polarizers to work which further reduces their vulnerability to ambient light. This is the big reason why LCD colors look as good as they do against CRTs in places like Best Buy even though LCDs have worse color gamuts. Retail stores are extremely well lit which plays to the comparative advantage of LCDs. Even Plasmas suffer from the bright lighting in stores due to the fact that they have phosphors.

CRTs have a reputation for great contrast ratios but it is a reputation that is undeserved in this day and age. The reputation was only valid in a bygone time frame.

 

[zephyrprime]

And by the way, even stuff like OLED will have a non-infinite contrast ratio because it's impossible to make a leak free, zero capacitance transistor or diode.

 

[JRW]

If contrast ratio is any indication of black level performance then CRTs are still way ahead of any LCD Ive seen, For example if my Sony XBR960 CRT is displaying a black screen at night with no lights on in my room the screen is *pitch black* Not a hint of light can be seen in fact you cant even tell the TV is powered on. On the other hand If my NEC 20WMGX2 LCD is displaying a black screen at night it still displays a surprisingly bright picture which is a medium grey instead of black. (thanks to the backlight).