4K TV Reviews

Full-On/Full-Off Contrast Ratio: 19,110:1

Pre-calibration measurements were made in the THX Cinema preset at the default settings. Post-calibration measurements were made with the Professional1 preset active. With the TC-65AX800U’s Max Adaptive Backlight Control switched on, its black level measured 0.002 ft-L and peak white 38.22 ft-L, for a contrast ratio of 19,110:1. With the Max Adaptive Backlight Control off, black level measured 0.013 ft-L and peak white 38.67 ft-L, for a contrast ratio of 2,975:1.

The average Delta E of the Panasonic’s pre-cal gray scale averaged out to 12.7; calibration resulted in a much-improved 2.2 average, with a high of 5.5 at 20% brightness. (Delta E is a figure of merit that indicates how closely a display adheres to the Rec. 709 HD color standard. Experts generally agree that levels below 3 are visibly indistinguishable from perfect color tracking.) The Delta E of the Panasonic’s color points at the THX Cinema mode’s default settings averaged an impressive 1.5. Calibration improved that to an even more impressive 0.3.

With the Adaptive Backlight Control set to Max, gamma in the THX Cinema mode measured 1.9, hitting 1.7 at 80% and 2.2 at 100%. Post-calibration in Professional1 mode, gamma measured 2.1, remaining close to that mark throughout the full brightness range. I saw no screen uniformity issues on the TC-65AX800U with its Adaptive Backlight Control switched on. All full-field gray test patterns looked evenly illuminated when viewed straight on. Off-axis performance was about average, with contrast and color starting to fade when viewed about 20° off from center-screen.

The Panasonic passed all of our standard- and high-def video-processing tests, except for high- and standard-def 2:2 pulldown.—AG