In fact this is a silly discussion ......
Assuming that your screen is outputting 40 ftL at full white, than black at 0,02 ftL represents a factor 2000 = 66 dB.
That seems quite enough as the best camera's have a dynamic range of 65 - 70 dB, BUT their actual s/n ratio is less than 60 dB. Add to that the losses that you have in the editing gear and data transport and you may be glad when your Blu-ray is outputting 55 dB s/n ratio. That is a ratio of about 560 !!! Easy, easy to display with any flatscreen.
And don't forget you have to add the losses you encounter when putting that excellent Blu-ray disc in your player .......
All in all a s/n ratio of 500 (53 dB) is probably a very good result.
So get your screens calibrated professionally and make sure that black actually means "light off".
This probably may not work for LCD owners due to the limited technology, but remember: you can improve your "black vision" by making sure that you are not in a pitch dark room!
"However, this is the S/N of the ADC and has nothing in common with the S/N of the camera. This is usually limited by the number of photons. In the case of the ADC, the dynamic range is usually specified. For example, a normal camera might have about 60-dB dynamic range and a S/N of 40 dB.
For a camera, the number of photons required to achieve saturation is the saturation capacity/QE. For a camera that requires 20,000 photons to reach saturation at a QE of 50% (0.5), the number of photons will be 40,000.
Since the noise is given as the SQRT (signal) = SQRT(40000) = 200, the S/N = 40000/200 = 200 = 46 dB or 7.6 bits. However, since the S/N of a camera is the number of electrons required for saturation divided by dark noise, a camera with 20,000 electrons full-well capacity and 15 electrons dark noise will yield a dynamic range of 20,000/15 = 1330 = 62.5 dB or 10.4 bits.
However, a camera’s S/N is not totally dependent on the S/N of the converter. The LightWise LW-5-S-1394 FireWire camera from Imaging Solutions Group (ISG), for example, uses Micron Technology’s 2592 × 1944 CMOS imager MT9P001. Despite the fact that the CMOS imager includes a 12-bit ADC, the S/N of the imager is specified as 38 dB. But the S/N of the camera is specified as “>38 dB.”
Rarely specified by any camera vendor, absolute sensitivity of a camera can be derived as a ratio between the dark noise and the QE of the camera. If, for example, the dark noise of a sensor is 50 electrons and the quantum efficiency of the imager is 50% at 550 nm, then the absolute sensitivity will be (50/(1/2)) or 100 photons. This is a measure of the minimum number of photons that can produce a minimum possible signal in the sensor or camera.
Often confused with S/N, the dynamic range of a camera is also expressed in decibels or number of bits. For sensors that behave in a linear fashion, the dynamic range is the ratio of the brightest unsaturated signal to the darkest possible signal detectable in the presence of noise. In the SI-1920HD MegaCamera from Silicon Imaging, for example, which uses a 1920 × 1080 CMOS imager, the dynamic range is 68 dB while the S/N is 52 dB at 0 dB gain. Since 68-dB dynamic range cannot be digitized with an 8-bit ADC, the SI-1920HD uses a 12-bit converter to digitize the signal from the sensor."
Coming from: http://www.optoiq.com/index/machine-...nce-specs.html