Here is a follow up to the post
I wrote in the F8500 settings thread showing the static contrast performance of 3 panels, one each in the D, E, and F series using the mll vs. apl patterns, along with the Panasonic VT50 and ST30. Of the Samsungs, the F series is of course significantly better at low APL scenes (a factor of 3 vs. the D8000 and a factor of 2 vs. the E8000 at 2% average luminance). It's surprising however that my tweaked panel outperforms the F8500 (3000 vs. 2500) above 7% average luminance @42ftL. ABL brings it back down to match around 42% average luminance. I should note too that the F series is capable of much higher than 42 ftL peak white where this comparison is made. The panasonics do not modify black level with APL and will therefore maintain a constant contrast ratio until peak white is affected by the brightness limiter, typically above about 30% average luminance.
For some context on average luminance levels here is an example of low vs. typical APL.
Typical - Average luminance is 15.1% on 2.2 gamma display
Low - Average luminance is 3.5% on 2.2 gamma display
Low - Average luminance is 4.2% on 2.2 gamma display
Summary of mll for low and typical luminance ranges:
and contrast ratio:
There are limitations to the perceivable benefits of high native contrast ratios, one of which is environmental lighting. Even in a dimly lit room say with several lux falling on the screen and a good AR coating, the reflected light will be at or above 0.01 ftL So to benefit from a display with mll significantly lower than this the first thing you have to do is turn off all the room lights.
The second limitation is the dynamic range of the eye's sensitivity. At any particular adaptation luminance the highest perceivable contrast ratio is ~1000:1 (some would put this lower, maybe 500:1) So if we take our typical average luminance level for a gamma = 2.2 display calibrated to 35 ftL and divide by the maximum perceivable contrast ratio at that adapted average luminance we get (15%) * (35 ftL) / 1000 = 0.005 ftL (ANSI CR = 7000) . So again, once you get into the mll range of 0.005 - 0.01 ftL you need specific conditions to occur in which you will benefit from an mll lower than this. One is minimal room light and the other is for scenes that are 2 or 3 times below typical average luminance levels.
note: Thanks to buzz, Make73, and Tom H for providing the data