Any CR numbers as high as you guys are discussing are insanely hard to measure and almost completely unbelievable. Photo Research has a nice instrument which I have used that could do it. The PR-810L and can do 0.000001 to 518,400 fL and 512,000,000,000:1 contrast ratio. Its also handy cuz its handheld and portable. http://www.photoresearch.com/current/pr810L.asp
But you need so many other things to make this measurement. God,, if a LED inside the unit someplace was glowing, its light might escape out of the case and pollute the measurement !.. Measuring really low fL levels with the right gear is insane, you need a special light tight room, you need to wear a black space suit kinda outfit. Even really weird things like body heat ( IR ) and IR from the device under test can pollute the measurements unless filtered out. In Plasma devices the UV needs to be filtered out.
For someone to have measured hyper high CR outside of laboratory conditions with a max output from a CRT makes me dubious about the results.
That said.. I would know about CRT black levels. I did make one of the best CRT FP's
And when a CRT tube is off, 0 IRE, its not completely "OFF" as you approach G2 cutoff its not a sharp edge. But yea, mostly its OFF.. Some stray electrons do illuminate the face of the tube just because of the 2nd anode being 30Kv, but thats about it. Well ok, the tube would act like a cosmic ray detector and a few photons would be produced by a stay particle from space
heheheheh... But these full of measurments are not a real CR !,, Thats full off. Once a tube is in use, its a very analog thing. The phosphor heats up and glows even after the white goes away. So quickly switching between full white and black is a whole different CR then slowly switching back and forth. Tubes are very non-linear and have temporal changes that need to be taken into account when doing measurements. A CRT is a very difficult moving target for measurements. Did you know that a CRT xy color point moves ever so slightly when its phosphor is hot then when its cold ? This changes in 100ms to seconds. Its also specific to the spot on the face of the CRT that is heated ( illuminated ).
Digital devices are much more digital
Not that they are better. Our visual system is very analog and nothing could be more foreign then a PWM light source from a DLP mirror.
But lets stay on topic.
We have a measured fL of 0.0008fL and HomeTheater had it at 0.001fL. These sound like the bottom of the meters ability and both these mags I dont think have a PR-810L. This does however give me a good idea of a reasonable expectation of what black should be.
Anyone else happen to have any real measurements of a exceptional system ?