Performance (How we test TVs)
Overall the GT30 delivered excellent picture quality, with deep black levels, accurate color, and the essentially perfect uniformity of plasma, with the surprising bonus of handling 1080p/24 content correctly. Compared with the GT25 from last year, it evinced worse gamma, which washed out darker parts of the image (an issue that also caused us to slightly prefer the ST30's image overall to that of the GT30), and showed some subtle fluctuations in black and gray areas. The TC-PGT30 is still a superb performer, however, and its strengths more than outweigh its weaknesses.
THX was the most accurate picture mode before calibration, but it left something to be desired, especially in terms of gamma and, to a lesser extent, grayscale accuracy. For our calibration, as usual with Panasonic, we tried using both THX (since it lacks most fine adjustments our THX "calibration" consisted mainly of increasing light output from 30 fL to 40 fL) and Custom, which allows more picture control (we ruled out Cinema as a starting point because its light output maxed at 30 fL). In the end THX showed superior color decoding and secondary color points, as well as marginally better gamma (albeit significantly worse than we measured last year); Custom won for primary color luminance and grayscale.
For our evaluation below we went with THX, mainly due to Custom's terrible red and green push in its color decoding (per Calman, if you're keeping track, Custom's saturation error [Delta C] was 6.96 and 10.11 for red and green respectively, compared with 3.75 and 0.27 for THX). A proper color management system could help take care of that, but none is available on the GT30, so for our Custom calibration we had to desaturate the whole image (see picture settings for details). Overall Custom fared better in the Geek Box, but THX definitely looks better in person. Of course, the availability of color calibration controls would have improved THX's Geek Box scores considerably.
For our image quality tests we chose "Tron" on Blu-ray and used the comparison lineup below.
|Comparison models (details)|
|Panasonic TC-P50ST30||50-inch plasma|
|46-inch edge-lit LED-based LCD|
|Samsung UN55D8000||55-inch edge-lit LED-based LCD|
|Vizio XVT553SV||55-inch full-array LED-based LCD|
|Pioneer PRO-111FD (reference)||50-inch plasma|
Black level: The GT30 delivered a deep level of black that equaled last year's excellent GT25 and measured a bit brighter than the UND6400--although the difference was nearly impossible to discern even in our side-by-side tests. It did measure a bit darker than the ST30, but side-by-side the visible difference was again nearly impossible to discern (we originally wrote that the GT30 was visibly darker, but that was because of improper adjustment, since corrected, of the ST30). The GT30 was quite a bit darker (better) than our Samsung PNC8000 review sample, but on the flip side visibly brighter (worse) than the Vizio, the Samsung UND8000, and of course the Kuro.
The differences were visible in areas like the letterbox bars above and below the image in most scenes, as well as dark scenes like the intro, with its bright blue lines on a black background that form into a computerized cityscape. In this scene we also noticed one major advantage the GT30, and other plasmas, had over the Samsung LED sets: the blue grid was brighter on the plasmas, creating a better sense of contrast.
On the other hand, we noticed abrupt yet relatively subtle shifts in the brightness of some shadowy areas. In the "dressing room" scene in Chapter 5, for example, the gray background of the room changed on three separate occasions we counted, getting a step darker or brighter in the shadows and, at the most noticeable point, the background to either side of a ring of light (28:16). We also noticed a shift in the bottom of the shaded window frame (Chapter 2, 5:41) as the camera pushed forward. None of the other TVs, including the ST30 and GT25, show similar shifts in these scenes.
Compared with the GT25 the GT30 maintained a more stable depth of black in one test. When we increased the brightness of a window pattern from 95 percent to 100 percent, the brightness of the surrounding measurement of "black" increased just 0.001 fL--a difference we found impossible to discern by eye--on the GT30, but on the GT25 it became visibly brighter to the eye, increasing 0.009 fL (which is still relatively subtle compared with the G20 we reviewed earlier).
These two tests are enough to convince us that the GT30 still exhibits the "floating blacks" we noted last year. They're somewhat uncommon and not a major performance issue for most people, but sharp-eyed viewers may find them distracting.
The GT30's gamma measured worse than the GT25 and differences were visible in program material. The face of the young Sam Flynn in Chapter 1, for example, seemed a bit flatter and more washed out than our reference. Shadowy and dark areas, such as in the rafters above the arena in Chapter 6, also looked too bright, robbing the scene of some contrast. Many of the other sets in our lineup looked better in this regard, and we consider this one of the GT30's most apparent performance issues.
Color accuracy: While the GT30 fared worse than some of the other TVs in our measurements, overall it was very good. In its favor, skin tones appeared relatively close to our reference, for example in the face of teenage Sam as he stands in the lobby of the police department. We did detect a greenish-reddish cast in some scenes compared with our reference, especially in brighter areas, but we doubt the difference would be visible outside of a side-by-side comparison. The GT30 also showed a significantly more accurate shade of black and near-black than most of the other sets.
Video processing: As we mentioned above, we were surprised that the TC-PGT30 passed our 1080p/24 test in its "60Hz" setting. It delivered a much smoother cadence with the proper look of film than did the GT25 from 2010, and was basically indistinguishable from the C8000 (in Cinema Smooth mode), the Pioneer, and the other sets with proper 1080p/24. The ST30 handled 1080p/24 the same way in 60Hz mode, so we assume Panasonic made a processing tweak this year. As usual we found the 48Hz mode flickered too much to be watchable.
[Update June 9] On the other hand we did notice some artifacts from 1080p/24 sources in 60Hz mode. On the "Digital Video Essentials" test Blu-ray we noticed shifting lines and minor instability in the downtown Philadelphia buildings during an upward-facing pan. We didn't see any similar issues during other program material, but assume they might crop up.
Panasonic also introduced dejudder processing this year with a setting entitled "Motion smoother." It delivers two options, Weak and Strong; they looked very similar to our eye, although Weak left a hint of more judder. As usual we found both relatively distasteful.
The GT25 from last year had a "Blur reduction control" that, when engaged, delivered full-motion resolution. That control has been dropped for 2011, but Motion smoother basically does the same thing: when it was engaged, in either Weak or Strong, we saw an increase in motion resolution in our test pattern (see the Geek Box). It's worth noting again that THX doesn't allow you to turn on Motion smoother at all, and as usual any blur was impossible for us to discern with real program material.
The GT30 passed our 1080i deinterlacing test with 3:2 pull-down set to On, but not when we used the default Auto (and, despite what the menu explanation says, this setting does affect HDMI sources).
Bright lighting: Panasonic modified the antireflective screen on the GT30, and as a result we saw deeper black levels and contrast under the bright lights than on the GT25 or the Samsung C8000, but not deeper than on the Kuro or the LCDs. We did notice brighter reflections in the GT30's screen compared with the GT25, but overall we still consider it an improvement and among the best plasma screens we've tested.
PC: The GT30 only accepts a maximum resolution of 1,366x768 pixels via VGA, so we don't consider it a good computer monitor. There's no auto adjustment we could find, so we had to manually dial in horizontal and vertical position using test patterns, and even then we had to crop a row along the bottom (or top). Text and other fine objects looked relatively soft.
3D performance: For our 3D tests we slipped in the appropriate disc from "Tron." Overall the GT30 was a very good 3D performer, showing minimal crosstalk compared with the others and delivering deeper black levels than the ST30.
In the dressing room scene, both of the 2011 Samsung LEDs failed to eliminate crosstalk to the same extent as the GT30, showing more obvious signs of the telltale doubling in areas like the edges of the room and the pattern in the floor below Sam (28:21). To be sure we still saw some crosstalk on the GT30, but it was mostly noticeable in very difficult white-on-black areas, like the title menus and the word "1989" superimposed over the image in Chapter 1.
We also appreciated that the GT30 (and ST30) lacked the annoying moire artifact we first noticed on the grid floor of the command room in "Avatar" (at 12:20, for example) when watching the GT25.
As usual we checked out 3D using the default settings--THX in the GT30's case--since we don't currently calibrate for 3D.
Power consumption: The GT30 uses a bit more power than the GT25 and GT20 from last year after calibration, although its default (Standard) picture is dimmer, and thus uses less power, than ever. In any case it can't hold a candle to LED models in terms of efficiency.
|Black luminance (0%)||0.0082||Good|
|Near-black x/y (5%)||0.3244/0.3412||Average|
|Dark gray x/y (20%)||0.3187/0.3346||Poor|
|Bright gray x/y (70%)||0.3181/0.3301||Average|
|Before avg. color temp.||6346||Average|
|After avg. color temp.||6370||Average|
|Red lum. error (de94_L)||5.1815||Poor|
|Green lum. error (de94_L)||3.0318||Poor|
|Blue lum. error (de94_L)||2.2478||Average|
|Cyan hue x/y||0.2242/0.3257||Good|
|Magenta hue x/y||0.3178/0.1542||Good|
|Yellow hue x/y||0.4254/0.4942||Average|
|1080p/24 Cadence (IAL)||Pass||Good|
|1080i Deinterlacing (film)||Pass||Good|
|Motion resolution (max)||1200||Good|
|Motion resolution (dejudder off)||800||Average|
|PC input resolution (VGA)||1366x768||Poor|
|Panasonic TC-P50GT30||Picture settings|
|Picture on (watts)||116.52||246.28||N/A|
|Picture on (watts/sq. inch)||0.11||0.23||N/A|
|Cost per year||$25.64||$54.08||N/A|
|Score (considering size)||Poor|