Originally Posted by TomCat
I learned a few things about these Vizios last night.
I had always suspected that since "Smart Dimming" modulates the backlight, that turning the backlight to zero would prevent SD from working. Apparently, not so; with the BL at zero, SD still works. So "zero" is probably not really fully off, and this is likely done to keep SD working with the BL turned low.
This has allowed me to upgrade my settings, moving BL from 15 to 7 (I had compromised by keeping it up at 15 to give SD some room to work with, which now proves unnecessary), and raising brightness and contrast 3 clicks each to compensate. I verified this using the grey scale from the HDNet TP, and the black and white points are still set just as good as before, if not even better. I also found that if you turn the auto-ambient light setting back on, they still track in light or dark, and track well enough to leave that setting on all of the time (although you must turn it off momentarily to actually change the BL setting).
Bottom line? Better pix than ever. And of course a lower BL is more energy-efficient as well.
It is pretty easy to verify SD working with the DirecTV screensaver on, as this is a blue logo floating "Pong-like" over a black background, and you can see the black area around the logo gets lighter than the rest of the background and this tracks as the logo moves. This is probably the most-difficult scenario for SD to appear transparently. It is even easier to see at a 45-degree look angle.
With normal video is is very nearly impossible to notice this particular artifact, however, which is as it should be. A dark wide shot with a full moon in it will just appear as if there were a little more natural haze around the moon or in the sky than normal while the darkest greys still seem naturally close to black, which is something acceptable because this appears normally in nature. What does not appear normally in nature is absolute black levels that are too grey or light, and that is of course what SD seems to prevent, effectively stretching the absolute black down where we want it dynamically. So, this makes SD very effective.
About the only other place I notice it is when a shot fades to black and back up; instead of a continuous smooth fade, there is a little jump at the point of threshold for SD, which is noticeable, yet not annoying. But this also makes full black really complete black, which I guess is the point.