Black Level & Contrast Performance
The Panasonic TX-P60ZT65B’s black-level performance is either minutely better than, or as good as, the legendary Pioneer KURO plasmas. This year’s best plasma TVs are already producing black levels that completely satisfy us, making us less concerned about what the exact minimum luminance level (MLL) measurements are than in previous years.
Both products have unique strengths and weaknesses when it comes to contrast performance, either measured or perceived. Pioneer’s plasma displays can still produce a brighter peak white than Panasonic’s. However, we feel that the Viera ZT65 has a superior anti-reflective screen coating to the Pioneer Kuros. That benefit will not be of interest for dark-room viewing of course, but for daytime viewing, it’s a step up.
One other observation is a very, very minor one which relates to the “cleanness” of the blacks. (This is extreme pixel-peeping, but that’s the sort of analysis you can expect from comparing two reference-level HDTVs). The KURO’s blacks tended to show a very fine “speckled” pattern with some pixels appearing minutely darker than others. It looked somewhat like static dither. Our understanding is that this was a very minor side-effect related to the use of Pioneer’s Crystal Emissive Layer (CEL), a panel layer which made those TVs’ extremely high contrast performance possible in the mid-2000s. We’ve also seen KURO plasmas which feature a more noticeable amount of this very minor speckling around the corners of the screen, which might suggest that the CEL itself on those panels does not age in a uniform manner. It is impossible for us to predict what the future holds for Panasonic ZT, although it logically follows that a simpler design should result in less unknowns.
The TXP60ZT65B does not use the CEL; its outstanding black level performance is achieved in a similar way to previous Panasonic plasma televisions. Therefore, the only pattern visible in a full swathe of black is that of the low-level interlaced reset pulses, which basically look like very, very small dark scanlines which scroll up the screen at high speed and are almost invisible. By the way, we’re not complaining about the presence of these, just noticing them, since we’re interested in the inner workings of a panel of this quality. The use of these interlaced reset pulses in the panel driving algorithm is one ingredient which allows for Panasonic’s world-beating black-level response. Unlike last year’s high-end Panasonic plasmas, all of the picture modes on the TX-P60ZT65 use this method to achieve deep blacks. Last year’s production model GT50 and VT50 series in Europe had this feature disabled in the “Professional” picture modes, resulting in slightly less impressive black levels compared to other picture modes (like the THX mode), but displayed higher gradation, which led us to believe that these two characteristics were destined to be mutually exclusive. In any case, it’s history: every single one of the picture modes on the ZT65 delivers high gradation and these class-leading black levels.
There’s some discussion online that suggests that the black-level performance, as assessed by measuring a fully black screen, is irrelevant to the TV’s real-world performance, and that ANSI measurements (which measure a black patch on screen surrounded by white ones) are the only way to go. This isn’t true; both are relevant. Measuring a fully black screen is only invalid if the television uses dimming tricks such as shutting the panel off (or dimming a light source, like LED LCDs do). Black level measurements are a valid means of keeping tabs on how the HDTV will perform with very dark programme material.
In any case, the TX-P60ZT65B’s ANSI contrast performance is also outstanding. It held onto its deep blacks during the ANSI checkerboard test better than any other Panasonic plasma, with blacks effectively staying put during this more difficult test, rising only by 0.001 cd/m2 to 0.004 cd/m2 relative to the full-screen black level measurement. Compare that to the step-down TX-P55VT65B, which had the same 0.003 cd/m2 full screen black level but 0.007 cd/m2 blacks assessed on an ANSI test. Just also remember that this difference is largely statistical. Due to the contrast detection characteristics/limitations of the human eye and brain (!) the tiny rise in black level is not visible due to the presence of brighter areas on screen to distract us. We imagine that the ZT65′s minutely superior ANSI contrast performance could be the result of the new Air Gapless Filter reducing flaring in the display. Either way, the difference is very small.
Whites dimmed to 68 cd/m2 with the ANSI checkerboard screen due to the use of automatic brightness limiting (ABL).
All of this means that the Panasonic ZT65/ZT60 has the deepest blacks out of any large-screen flat panel TV currently on the market, but not necessarily the highest contrast ratio once the peak white performance is brought into the equation. Both the Samsung PS64F8500 we recently reviewed, and the Pioneer KURO plasmas, are able to produce brighter peak whites. You really can’t go wrong with any of these TVs – they’re all first rate – but there will be viewers who favour Panasonic’s world-beating black level and sufficiently bright peak luminance, just as there will be users who prefer Samsung’s sufficiently dark blacks and exceptionally bright peak whites.
The effects of this level of contrast performance are profound. During hard cuts to black during nighttime viewing with the lights shut off, we actually found ourselves scanning our eyes left and right, trying to find where the edge of the screen was. Of course, the TX-P60ZT65 doesn’t produce 0 cd/m2 black, so in a fully dark room with a dark screen you’ll just be able to make out where it is, but thanks to the human visual system’s “surround effect” that we explained earlier, the blacks will appear to basically disappear to your eyes and brain with just a little bit of content on screen.
We don’t have a scientific way of assessing the quality of the antireflective screen coatings yet, but subjectively assessed, daytime performance is also in the highest category of performance that we’ve ever seen from a plasma display panel (PDP). Panasonic promotes the TXP60ZT65B as having a new filter called “Ultimate Black”, and it does appear that in daylight environments, there is an improvement over the (already outstanding) VT65 series. In any case, the performance it wonderful: daytime blacks on the ZT65 are like looking at glossy black velvet.
What we can do though, is provide a scientific comparison of the Panasonic ZT65′s “Ultimate Black” filter’s bright-room black level performance versus the “Infinite Black Pro” filter on the TX-P50ST50 we have here. In fact, we measured the latent light present in both televisions with the room lighting on with both panels turned off (both naturally beside each other), to measure only the performance of the filters. In both cases, we held the Klein K-10 colorimeter roughly half a metre from the screen surface. In this test, the ZT’s filter kept blacks as viewed in a bright room at just 0.05 cd/m2, whereas the ST50 – which manages an extremely deep 0.009 cd/m2 in a dark room – lit up to 0.35 cd/m2 in the presence of light. The bottom line is that the TX-P60ZT65B’s contrast performance is utterly spectacular, regardless of the viewing conditions. Would we recommend one for use in a very, very, very bright room? Not really, but that’s largely because a display of this quality would be put to waste in these conditions anyway. If you do decide to put a 60ZT65 in these conditions, it’ll give you a better image than many competitors.
Motion performance is excellent, with 1080 lines being reproduced cleanly for the most part in a resolution scroll test, and false contours during motion being kept at a very low level. Fast motion still reveals dithering, but that’s the nature of a plasma display, and Panasonic’s panel driving is the cleanest on the market, striking a very fine balance between injecting dither during motion to conceal contouring, and degrading static parts of the image.
There will still be viewers who prefer Pioneer’s “PURE” panel driving method, which featured degraded overall gradation and increased noise (a coarser image) in exchange for more consistency between static and moving performance. We’re aware of the benefits and disadvantages of both approaches and prefer Panasonic’s, which produces a very clean image with only small false contouring artefacts during motion. This is the best sweet spot, in our opinion, and it makes a real difference for users who sit close to the screen (video gamers being the most obvious example).
As usual, troublesome European 50hz content is output by the panel at 100hz (or something technically equivalent to it). We ran our custom 50hz tests through the TXP60ZT65B, and saw little drop in performance in terms of gradation and false contouring relative to the excellent 60hz quality. Only very small purple stripes appeared in skin tones.
Given the Panasonic ZT’s status as an ultimate, top-end 3D plasma TV, we immediately wondered if it would feature full-resolution 3D output 100% of the time. The answer is no, it doesn’t: like nearly every Panasonic plasma 3DTV, the brightest and darkest screen updates are drawn at 1080p resolution, with intermediate brightness steps being displayed at 540p (a side-effect of a panel drive system known as “single-scan 3D”). That, quite perversely, means that this flagship display is bettered in terms of outright three-dimensional resolution by midrange Samsung plasmas (we’ve not seen any of those this year, but it was true last year), Panasonic’s earliest 3D TV, the VT20, and also correctly-designed active-shutter-glasses (ASG) LED LCD TVs. Resolution is just one part of image quality, of course.
Of course, this 3D screen updating mode is included on Panasonic plasmas for a good reason: we’re advised that reducing the resolution where it won’t be missed (as much!) allows the plasma panel to produce better gradation and better contrast than would otherwise be possible. Samsung’s F8500 plasma, however, manages an even brighter extra-dimensional image which is 100% full resolution, but with poorer greyscale performance (false colour tints at different brightness levels). Therefore, there’s a good amount of evidence to also suggest that using “single-scan 3D” indirectly reduces these false colour tints. (That’s a bit of a moot point for almost all users though, because the greyscale performance of both will suffer from visible colour tints unless the 3D mode of the television has been competently and scientifically calibrated).
3-D performance on any plasma display is a step down compared to the beautiful 2D quality. That’s still the case here, but the TX-P60ZT65B can produce a pleasing tri-dimensional experience with sufficient brightness for darker rooms. We used the “High” panel brightness setting for obvious reasons, despite the fact that it results in more panel-generated noise (some of which appears in chunky 2-pixel-high units due to the use of single-scan 3D). Watching calibrated 3D video and enjoying the relative lack of tints brought on by inaccurate greyscale tracking is still addictive, it’s just a shame that few people will ever get to see 3-dimensional content this way.
As usual, there are also no motion problems in 3D, with each input refresh rate (50hz, 60hz, 24hz) being output without judder.
While Panasonic’s standard-def performance is totally serviceable, Samsung HDTVs which use their own video processing solution (such as the F8500) still have a better array of tools on board to deal with low-quality SD sources. Arguably, the filtering of standard-definition material is one of the video processing areas where there is an art to the design, rather than simple “does it work correctly: yes/no” questions (such as “does the film mode detection work all the time”).
Still, although the TX-P60ZT65 can’t do as good a job at concealing compression artefacts from appalling SDTV channels as the PS64F8500, it does a very job of providing crisp, clear scaling and jaggies-free deinterlacing. Film mode detection for SD content also works correctly, too.
The clean, high gradation, low-dither panel driving, outstanding anti-reflective screen coating, sublime black-level performance, suitably bright peak luminance, accurate greyscale, gamma and colour, and lack of any troublesome forced video processing features… all combine to make the Panasonic ZT’s picture quality some of the best we’ve ever seen on a flat-screen HDTV during both daytime and nighttime viewing. For someone with a vested interest in film and high quality reproduction of it in the home, it’s impossible not to get a little emotional at the results this panel produces, but we’ll avoid embarrassing ourselves with a fountain of superlatives, and just provide the facts.
High contrast performance, in particular on a screen with very deep blacks, provides a sort of effortless vibrance to images. Displays like this allow for rich, punchy video which still looks natural, unlike mid-2000s era LCDs and many current projectors which come equipped with wide colour gamut modes in an attempt to compensate for other performance deficiencies (be they in the panel in the former case, or in the viewer’s room in the latter). Actually, the ZT65 does famously support nearly-full coverage of the DCI colour standard, but since we’re watching normal HD content, we’re talking about the performance with the normal HD (Rec709) colour gamut.
There are essentially no problems to report. We threw our usual barrage of torture tests at the Viera TX-P60ZT65B, and looked for luminance instability (with both dark and bright content), rogue noise reduction systems (there aren’t any), and bandwidth limitations for both luma and chroma (the black and white and coloured layers which make up the image). The latter point is worth mentioning because HDTVs like the Pioneer PDP-LX5090 exhibit high frequency luminance roll-off, meaning that very tiny details on that display did not reach the panel (just because a panel uses a 1920×1080 pixel grid is not a guarantee that the frequency response is flat).
Actually, the ZT65′s frequency response isn’t flat either: bizarrely, it still applies just a tiny bit of gain to high frequencies in the image, and also appears to be doing selective processing to low frequency areas (which causes an odd “four leaf clover” shape to appear on a luma zone plate test card). Fortunately, this isn’t a big deal and has no visible effect with programme content. Once again, these are not substantial differences or noteworthy performance characteristics, but this is what we have left to talk about when we’re discussing a TV of this quality.
Screen uniformity was visibly perfect on the unit we reviewed. We would imagine that, given any discrepancies in what’s coming off the production line, that the best panels will be diverted to ZT65/ZT60 usage – in fact, given the price point, we would hope that would be the case.
Calibration is also absolutely worthwhile on the TXP60ZT65B. Compared to the uncalibrated presets, we were left with a much richer image with a better perception of depth: actors stood out from the background thanks to the accurate gamma and greyscale characteristics, with the more neutral white point resulting in less of a coloured “barrier” appearing over the image.
Plasma display technology and gaming are a match made in heaven. Too many people are put off using plasmas for gaming because of image retention (where static score counters or other on-screen displays can leave temporary shadows of themselves on screen afterwards), or worse, actual permanent damage (which is much rarer). That’s a huge shame, because the high-speed panel response achieved natively without the use of motion-compensated interpolation tricks means that plasma is the only way (ridiculously expensive OLED aside) to experience 60-frames-per-second gaming (from rare console titles or PCs) with full motion clarity and next to no input lag.
Specifically, the Panasonic TX-P60ZT65 lags by only 41.5ms when measured with the Leo Bodnar input lag tester, in its fastest configuration (achieving it is as simple as turning on [Game Mode] and disabling [1080p Pure Direct]). Most current-gen console games only run at a low frame rate of 30fps which is a pity, but even 30fps games feel considerably more responsive when played on an HDTV with low input lag. When assessed with our original lag test measurement method (which uses a CRT and high speed camera), we measured lag as being 23ms.
Subjectively, games felt great on the TX-P60ZT65B, as they have done on other Panasonic plasma televisions from the GT60 series and up (the ST60 uses a different video processor which resulted in poorer gaming performance). We do pay attention to forum discussions about input lag, and one common misconception is that because input lag figures are small (even less-than-optimal ones like the cheaper Panasonic ST60′s slower 60ms+), then they couldn’t possibly matter to anyone with less than superhuman reflexes. This is false, because playing video games is not a simple “one off” reaction test, but instead a constant feedback loop between the player and the screen. In any case, input lag is not a problem that the Panasonic ZT has.
For computer use, the TXP60ZT65B, like other 2013 Panasonic plasmas which use the company’s own video processor, has a slight vertical chroma bandwidth limitation which means that it can’t show every finely coloured detail from a 4:4:4 (computer) source as advertised. We tend to find that most users misunderstand this limitation as being more serious than it is, and while we’re helping Panasonic improve this aspect of the ZT65′s performance if possible, we don’t feel it’s a big deal given that plasma TVs are not suited for desktop computer usage (and the small vertical softening on the coloured details from computer sources won’t be visible during most games).
We’ve assigned “Reference Level” ratings to no less than three of Panasonic’s 2013 plasma ranges, starting from the GT60 and up. Each one is marginally better than the last, but the ratings reflect the fact that we were completely satisfied with all of them, and couldn’t see any areas that had been degraded by human error or pointless misfeatures (minor luma and chroma frequency response quirks notwithstanding, but denying a rating based on these would be needlessly punitive).
As is typically the case with high-end AV, the Panasonic TX-P60ZT65′s outstanding performance comes at a high price tag (especially in Europe compared to other markets). That means that buyers will pay a large premium for access to the unique Air Gapless Filter feature, which does away with internal reflections (which we didn’t find to be a problem on the VT65 series), and also appears to increase contrast performance gradually.
It’s a shame Panasonic didn’t see fit to bring the 65-inch version of the ZT65/ZT60 to Europe. We imagine that for interested buyers, this will result in many hours of deliberation in an attempt to pick between a cheaper, bigger 65in VT, or spending more cash to get a better quality 60-inch ZT. (America gets 65″ versions of both, but in Europe we were treated to the affordable and outstanding GT60 series, which that territory didn’t get in any size).
We’re a little disappointed that a 3DTV of the 60ZT65B’s calibre is still using single-scan 3D, which perversely means that it’s beaten by considerably cheaper displays when it comes to outright 3-dimensional resolution. This method seems to provide other benefits for 3D playback, however, and it’s a minor point which is overshadowed many times by the 2D performance.
And it’s really the 2D performance which is of most interest to us and most of our readers, which is what we award the “Reference Level” rating based on. The Viera TX-P60ZT65B exhibits all of the typical Panasonic plasma qualities (and the very minor downsides), and new for 2013, does so with higher light output and higher levels of gradation than before – and provides both of these characteristics simultaneously without brightness tradeoffs. It also improves on last year’s black-level performance both during dark-room and bright-room viewing.
We’ve analysed several outstanding HDTVs in our time, and that has especially been the case in the last few months, where we’ve been treated to an onslaught of plasma televisions that are all phenomenal in one way or another. You can’t go wrong with any of them, but weighed up subjectively, the strengths of the TXP60ZT65B arguably do make it the best HDTV we’ve ever tested. Of course that doesn’t mean it’s perfect: if you don’t like Panasonic’s approach to panel driving (which, in our opinion, is a great balance between smooth, clean images and sufficient, but not total suppression of false contouring during motion) then you still won’t like the ZT. The same goes if you just flat out do not like plasma displays. We believe that the vast majority of viewers will be wowed by the picture quality of a calibrated TXP60ZT65, though.
Is it worth spending such a large sum of money on a television that “only” provides 1920×1080 resolution, when we know that Ultra-HD displays (3840×2160) are coming? Yes. Currently, we are in a very, very good spot for high quality image reproduction in the home. We have swathes of 1920×1080 Blu-ray Disc content that is best viewed 1:1 on a high quality 1920×1080 display. It is unlikely that consumer Plasma TVs in a higher resolution will be released due to the implementation challenges, meaning that the first wave of Ultra HD 4K TVs are all LCD-based. The Panasonic ZT65 will eventually be bettered by Ultra-HD OLED televisions, which are some way off and, resolution aside, are honestly unlikely to significantly improve on the outstanding picture quality that the best plasmas are offering right now.
So, there you have it. Panasonic have hardly set a foot wrong with their 2013 plasma range (and given the intensifying competition, that’s just as well), and the Viera ZT is the very best product that they have to offer. In 2013, gas and phosphor still rule. If you want lucid, emotive images that are of the highest quality available in your home today from a flat-screen TV, then there’s no better choice than the Panasonic TX-P60ZT65B.
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