Panasonic TX-L42ET50B 3D LED LCD TV Review

2D Calibration

Note: Our Panasonic TX-L42ET50B review sample was calibrated using Calman Professional, the industry-leading video calibration software.

To assess the picture quality on offer to users who won’t be having their ET50s individually calibrated, we set the picture up as best we could with our eyes alone. That involved selecting “True Cinema”, turning down [Sharpness] to avoid edge sharpening artefacts, turning off [16:9 Overscan] to see the entire picture without the edges “zoomed off”, and finally, adjusting the LED intensity to match our room brightness with [Contrast].

Then, we measured how neutral the TX-L42ET50B’s grey shades were – important, because if these are tinted in any way, then all the other colours on the screen will be tinted, too.

Greyscale

Pre-calibration RGB Tracking
Pre-calibration RGB tracking and delta errors (dEs)

We found that the True Cinema mode’s pictures were slightly red-tinted overall, but also suffered from the common LED LCD inaccuracy of blue-tinted shadow areas.

Post-calibration RGB Tracking in [True Cinema] mode
Post-calibration RGB tracking and dEs in [True Cinema] mode

We used the [White Balance] controls, together with our Klein K-10 meter, to adjust the Panasonic TX-L42ET50 for optimum picture quality. We attempted to decrease the amount of blue in the lower end of the Greyscale to fight the blueness imposed by the LEDs, but that left us with too little blue (and too much red/green) in the brighter areas. In the end, we had to admit defeat and just accept some remaining blue-tinted shadows as one of the several picture quality concessions of LED LCD.

Gamma

Gamma curve in [True Cinema] mode Gamma tracking in [True Cinema] mode
Gamma curve in [True Cinema] mode Corresponding gamma tracking

Gamma tracking is a strength of Panasonic LCD HDTVs compared to their consumer Plasma counterparts, at least when Dynamic Backlight systems are disabled. The TX-L42ET50B managed nearly flat gamma tracking, meaning that no intensity levels (stages of brightness) were overly dull or overly bright. The exception, of course, is the shadows. You’ll see a slight bend downwards on the Gamma Y chart, indicating that dark areas of the picture are not as dark as would be ideal. This is down to the contrast performance limitations of IPS LCD panels, something we’ll explore when we watch actual content on the ET50, rather than just test signals.

Colour

Pre-calibrated colour was decent, but not exceptional. The biggest error was that Blue was desaturated and overly bright, with deep blue oceans appearing slightly less vibrant than would be ideal. We thought that this would be a limitation of the LCD panel itself, but as it turned out, we could get nearly all of the required vividness back by adjusting the controls in [Colour Management]:

Post-calibration CIE chart in [True Cinema] mode
Post-calibration CIE chart with reference to HD Rec.709

The end result is very good indeed, with a mildly blue-tinted magenta and cyan – and a nearly unnoticeable lack of saturation in blue – being the only points of contention. Panasonic doesn’t provide control over Cyan, Yellow or Magenta on the TX-L42ET50, so these had to stay as is.

Post-calibration Luminance levels in [True Cinema] mode
Post-calibration colour luminance (coloured bars = targets; black bars = measured values)

Likewise, although Luminance controls for Red, Green and Blue are provided, there’s nothing for the secondary colours, and unlike on the ST50 plasma, our trick of turning down the main [Colour] control and then re-adjusting Red, Green and Blue didn’t work on the ET50 LED TV. The resulting accuracy is still excellent, though, and we’d be lying if we said we could actually tell that Magenta and Yellow were slightly too bright.

3D Calibration

With the supplied active-shutter 3D glasses in front of our Klein K-10 meter, we ran Greyscale measurements with the Panasonic TX-L42ET50B’s 3D mode engaged, to get data on how neutral the extra-dimensional image appeared through the glasses in the accurate “True Cinema” mode. We find that accurate imaging is just as important in 3D as it is in 2D, especially on the Panasonic ET50, which can produce an exceptionally high quality 3D image that more or less matches the quality of 2D (more on that later).

First though, we put the 3D eyewear on to verify basic settings. As it happens, the default [Brightness] setting on the TX-L42ET50 is slightly too high in 3D, causing a little “below black” information to be revealed, which could translate into slightly less rich blacks in real world viewing – although the inaccuracy is so small, it’s likely to go unnoticed. With the glasses on, we reduced this by 3 clicks so that the video processor chip’s black level setting was at the correct point.

Greyscale

3D Pre-calibration RGB Tracking
3D Pre-calibration RGB tracking and delta errors (dEs)

As with its 2D performance, the ET50′s grey shades had slightly too much red in them. That’s actually reassuring, because with many 3D Plasmas – Panasonic’s included – the pre-calibrated 3D greyscale tracking can be much more wacky than the example presented with this LED LCD. By 3D TV standards, this is pretty good going, and the red tint will probably go unnoticed by many.

3D Post-calibration RGB Tracking in [True Cinema] mode
3D Post-calibration RGB tracking and dEs in [True Cinema] mode

Calibration was easy, with brilliantly neutral Greyscale shades taking almost no time to dial in. Of course, the same problem exists as in 2D, with it not being possible to fully defeat the purple-tinted blacks we often see with LED-based LCDs.

Colour

Before calibration, colour in 3D suffered from some inaccuracies. Green was slightly off hue, and blue was surprisingly undersaturated.

We managed to massage things back to near-2D levels of accuracy using the [Colour Management] menus, but as we often find, we couldn’t fully saturate blue in 3D mode. We found that correcting some of the luminance inaccuracies was necessary before hue and saturation would fall into place. In any case, we were content that colour reproduction was of a good, but imperfect standard after calibration – much as it was in 2D. We’ll be sharing our calibrated settings on our forum, due to the fact that 3D calibration is such a rare practice.

3D Post-calibration CIE chart in [True Cinema] mode
3D Post-calibration CIE chart with reference to HD Rec.709
3D Post-calibration Luminance levels in [True Cinema] mode
3D Post-calibration colour luminance (coloured bars = targets; black bars = measured values)

Benchmark Test Results

Dead pixels Some stuck subpixels visible on black screen
Screen uniformity Some uneven light, but excellent for a side-lit LED LCD
Overscanning on HDMI 0% with [16:9 Overscan] set to “Off
Blacker than black Passed
Calibrated black level (black screen) 0.16 cd/m2 (in the fixed backlight “True Cinema” mode)
Calibrated black level (ANSI checkerboard) 0.16 cd/m2
Black level retention Stable in [True Cinema], dynamic backlighting used otherwise
Primary chromaticity Good (pre-calibration), Very Good (post-calibration)
Scaling Excellent
Video mode deinterlacing Very effective jaggies reduction
Film mode deinterlacing Passed 2-2 PAL and 3-2 NTSC tests
Viewing angle Very Good for an LCD TV; colours remain largely saturated but blacks brighten
Motion resolution 1080 (with [Intelligent Frame Creation)]; 300 (without, and in Game mode)
Digital noise reduction [P-NR] is optional
Sharpness No unwanted sharpening noticed with real content, but luma zone plate reveals mild artefacts
Luma/Chroma bandwidth (2D Blu-ray) Full Luma, Full Chroma
1080p/24 capability No judder in 2D or 3D
Input lag 24ms compared to lag-free CRT
Full 4:4:4 reproduction (PC) No, 4:4:4 input subsampled

Power Consumption

Default [Normal] mode (2D) 62 watts
Default [Normal] mode (3D) 84 watts
Calibrated [True Cinema] mode (2D) 63 watts
Calibrated [True Cinema] mode (3D) 78 watts
Standby 1 watt

Measurements taken with full 50% grey screen, to approximate most picture content.

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