Black Level and Contrast Performance
Panasonic’s plasma TVs don’t have any shortage of strong points, but black level is probably the most widely acknowledged and promoted out of these. Their plasmas absolutely destroy the competition in terms of black level performance, and unlike an LED LCD TV, this black level performance is not achieved at the expense of dulling other areas on screen. That means that on HDTVs like the Panasonic TX-P42ST60, jet-black areas can be shown on screen simultaneously with incredibly bright whites.
So, numbers! How does 0.005 cd/m2 sound? Yep, this £900 plasma television can produce a shade of black so deep that it’s only second to the reigning champion, the (we’re sorry to keep talking about these) discontinued Pioneer KURO plasma displays which were many times more expensive. Keep in mind that such a deep shade of black is actually unmeasurably low and confuses most calibration instruments: the blacks on the TX-P42ST60B are so dark that most devices can’t even register them. Our Klein K-10 is one of few that can, so keep this in mind if you hear the black level on this TV quoted as something like “0.02″ or “0.03″ – it’s in fact much lower.
0.005 cd/m2 represents a not insignificant improvement over last year’s Viera ST50 series, which came in at an already outstanding 0.009 cd/m2. It’s as good as the best viewing mode (“THX Cinema”) on last year’s flagship Panasonic TX-P65VT50, and on nearly equal footing with the KUROs.
The Viera TXP42ST60 also held onto its deep blacks, for the most part, during the ANSI checkerboard test. When white patches had to sit on screen simultaneously with black ones, the blacks only rose by 0.002 cd/m2, resulting in a reading of 0.007 cd/m2. Such a tiny rise is invisible to the human eye in the presence of brighter areas, anyway.
Deep blacks are one part of the contrast equation, but it’s of limited use if the peak light output is curtailed: truly jaw-dropping video requires high contrast performance on both ends of the spectrum. The Panasonic ST60 delivers here too, with no shortage of brightness. We didn’t have any trouble getting 120 cd/m2 of peak luminance out of the 42ST60, and in fact could have pushed it higher, but at these giddy contrast heights, the picture was more than bright and deep enough.
Displays featuring contrast performance of this quality are the closest thing we have to large-screen, affordable OLED TVs today – we could hardly be any happier with the contrast performance. That number again: 0.005 cd/m2 – getting close to pure black. In a pitch black room with your eyes acclimatised to the darkness, you’ll still be able to tell the difference between the darkness and the panel (you can blame the evolution process for that, not Panasonic!), but even with just a little bit of ambient light in the room, such as bias lighting behind the HDTV or a few bright elements on screen, your eyes will struggle to tell the difference.
Last year, we raved at length about the increase in motion rendering quality brought about by Panasonic’s then-new Focused Field Drive (FFD) system. From what we gather, this new panel driving algorithm allows the timing of the various plasma light output stages (which together result in the drawing of a single frame) to be better adapted to the luminance characteristics of the specific image being displayed, rather than adopting a more linear “one size fits all” approach. In practice, the adoption of Focused Field Drive coincided with cleaner motion quality with less distracting noisy doubled after-images during very fast content (for example, 60fps video games or sports).
We ran the TXP42ST60B side by side with our own 50ST50 from last year (rated at “2000hz Focused Field Drive” compared to the 42in ST60′s “2500hz” upgrade), and had a look at both 50hz and 60hz high motion content. We couldn’t see any difference when compared to the excellent performance from last year, which is fine by us. As usual, the TX-P42ST60 can resolve all 1080 lines on the (60hz) FPD Benchmark scrolling test without any extra help from the motion interpolation system. During the difficult tests here, motion artefacts were limited to some mild green and purple “phosphor trails” clinging to the edges of very fast moving objects. Engaging [Intelligent Frame Creation] on the “Min” setting reduces these further, and instead produces very mild motion interpolation artefacts (but crucially, does not give films a “soap opera” look). The choice is here, so Panasonic has once again covered all bases.
Motion quality during 50hz high motion content – for example, sporting games on European TV – was still good, but not as good as 60hz. This is inevitable on a PDP (plasma display panel): the 50hz field rate being clung onto by European broadcasters is too low to be output natively without causing annoying flicker, so all current plasmas output 50hz signals at a doubled rate of 100hz to move it out of eye-fatigue territory. However, to achieve the same panel brightness at the higher refresh rate, something has to give in the grand plasma juggling act: the result is slightly coarser gradation, where fast moving objects can appear to break up into oily-looking stripes. The effect is mild, though, and we personally still prefer this over LCD panel blur.
Also, owed to the fact that one 50hz frame is output twice before the plasma panel emits black for a fraction of a second, the human eye perceives very fast camera movements to appear with a little bit of double imaging. We’re talking about the PDP’s native performance here, by the way: Panasonic’s [Intelligent Frame Creation] system helps counter these mild and inherent characteristics. Using the “Off” setting, naturally, results in the panel displaying the content as-is without the processing. There are also Min, Mid and Max settings. “Min” is the one to go for with fast 50hz content, in our opinion: it preserves the motion fluidity of the original content, still operating at the 100hz (50hz x 2) refresh rate, but it greatly reduces the “oily” tone jumps (false contours) and also the double imaging effect. What’s more, it adds only a very small amount of discernible digital motion interpolation glitches (for example, the edges of score counters and other on screen graphics “shredding” when the camera moves). The “Mid” setting is the same, still operating at a multiple of 50hz (to avoid introducing judder) but with more aggressive motion interpolation, which we didn’t feel was necessary. Finally, there’s a “Max” setting, which uses high motion interpolation and also internally converts 50hz content to 60hz, which is the plasma panel’s own sweet spot in terms of freedom from flicker and high gradation. However, converting 50hz content to 60hz output results in a rhythmical motion stutter visible with very fast movement, owed to the difference in frame/field rates. For that reason, we stuck with “Min”, due to its preservation of output timing and relative freedom from artefacts.
Another great design touch is that this option is saved independently for video content and film content. You can have [Intelligent Frame Creation] set to “Min” to get the overall best quality possible with troublesome 50hz content, but movies on Blu-ray at 24p are under the jurisdiction of [24p Smooth Film], which we left off. So, you can have 50hz TV given a little extra help with [Intelligent Frame Creation] but pristine 24p Blu-ray content (which is too low a frame rate to reveal many motion artefacts) can be output without any motion interpolation – all without needing to jump back and forth in the menus.
Overall, the motion quality looks identical to last year’s Viera ST50 to our eyes, and that is cause for celebration.
On the whole, the Panasonic TX-P42ST60B produces a very enjoyable three-dimensional experience. Once again, it uses Panasonic’s clever (and not entirely concession-free) 3-D panel driving algorithm. In a nutshell, this output mode means that in the duration of one video frame, Panasonic plasma 3DTVs are effectively switching between 1080p and 540p at high speed (Panasonic internally refers to this as “Single Scan 3D”, although their marketing division has never made the distinction, instead choosing not to confuse matters and referring to all of the displays as “Full HD 3D” – albeit with a subtle disclaimer). That can cause jaggedness to be visible during motion in the third dimension, but the upside – we’re told – is better gradation with less panel-generated dither, and better contrast.
We’ve talked about the disadvantages of this mode before (we’ll get to the advantages in a second), namely that it results in Panasonic’s 3D plasmas not being able to display a full (vertical) resolution tri-dimensional picture at each brightness step. We know that the subfields (the light emission stages) responsible for drawing the brightest and the darkest parts of the picture are drawn at full 1080p precision (which explains why these 3D TVs can cleanly draw a simple white and black line pattern, like the kind commonly used to assess resolution), but inbetween shades, which always occur in real photorealistic film content, are actually output at the equivalent of 540p, with each second line being a repeat of the one above.
That on its own, would result in obvious resolution degradation and line twittering (as was visible on some older Panasonic plasma-based 3D televisions which used an earlier version of this technique), but Panasonic later suppressed the resolution loss with extra video processing (which detects diagonal edges in the picture and effectively anti-aliases them). While our trained eyes can still pick up on this clever trick, we are the only publication ever to comment on it (partly because we were intrigued by it and partly because it makes its mark on the picture) – so keep that in mind when you consider how visible it is.
Clearly, a lot of thought has gone into the design of the 3-D panel driving mode. Why would Panasonic’s engineers risk degrading the picture by scanning intermediate shades at half vertical resolution – on a display branded “Full HD 3D”, no less? Well, there’s a good reason. Skimping on screen updates in this way means that the addressing portion of the plasma screen updating cycle takes up less time – and that in turn means that there’s more time left for improving the gradation of the picture, and also keeping it sufficiently bright (very important for 3D). We’re also informed that it results in better black level quality in the third dimension.
This is borne out in real world usage. By plasma standards, the TX-P42ST60′s 3D images are suitably bright, and when compared to Samsung’s 3D plasmas – which operate at full vertical resolution at all times – Panasonic’s feature less dithering noise in the image with smoother transitions, and also much better, more consistent greyscale tracking quality (see our calibration charts above).
However, the half-resolution intermediate drawing steps can still rear their head(s). During motion, the secondary “antialiasing” subfield trick either does not work or is not attempted, so, for example, during the fly through Paris at the beginning of Hugo, you’ll be able to see some jaggedness visible on the diagonal rooftops and architectural details, where the loss of vertical resolution can’t be concealed. Still, we understand why Panasonic would use this interesting method.
When we sat back to take a look at 3-dimensional content, we were overall very happy with the picture quality. As usual, the TX-P42ST60B can output any type of 3D material you throw at it without any TV-added motion judder: 24hz, 50hz and 60hz content are all output using refresh rates which are perfect multiples of the input rate, unlike many LED LCD TVs (although interestingly, not Panasonic’s – the company seems to be totally on top of this) which force everything through a “one size fits all” 60hz design.
Especially after calibration, and to a decent extent before, Hugo‘s earthy teal and orange tones came through undisturbed, with only a small amount of crosstalk visible during the more difficult moments. Of course, the picture quality is still rougher than in 2D, owed to the huge extra work imposed by the doubled refresh rate – and it’s unlikely we’ll see an improvement on this until OLED appears. We also could see some pink pixels flickering in highlight areas of the picture, although the effect wasn’t hugely distracting.
SD performance on the 42-inch ST60 was great as usual. To make it quick – scaling is outstanding with full detail preserved (if it’s even in the source) and with a sharp look, despite there being almost no ringing. Video mode deinterlacing is extremely effective at reducing jaggedness, and the film mode detection works correctly during tests, provided it’s turned on in the menu of course. The ST60 does bias the detection in favour of video, though, because the resulting artefacts from film misidentified as video are better than the opposite scenario (we did occasionally find this happening in real usage from TV).
Given how good the standard-def performance is here, we’re curious to see what the “Hexa-core” Panasonic models (GT60, VT60/VT65 and ZT60/ZT65) can do to improve on this.
2D high definition content is where Panasonic’s plasma TVs really shine. Whenever one of these panels come through for review, we inevitably line up a stack of the best Blu-ray Disc video transfers, and get lost in the picture quality that results. The ST60 is business as usual in this department: the image quality is simply lush. The core component, the Panasonic NeoPlasma panel, produces fantastic motion clarity, serves up a picture that’s free from viewing angle restrictions, and has better uniformity than the common edge-lit LED LCD competition. The high contrast imagery is the most important ingredient, and Panasonic has once again improved on this compared to last year.
Thanks to cheap and plentiful Blu-ray Disc players (many of which work properly without abstracting the picture), (usually) well-mastered content to feed them with, and last but absolutely not least, HDTVs like this one, you can get video quality in your own home for a three-figure price (or just over) that would give tens of thousands of pounds’ worth of studio equipment a run for its money – as long as you get the setup right. It’s hard for film and video lovers to not be ecstatic about that, but we think it’s a point that’s often missed in the consumer electronic industry’s constant upgrade-itis.
With few small hiccups over the years, Panasonic have demonstrated that they understand the need to leave high quality video alone without tinkering with it. In the True Cinema mode, the TX-P42ST60B features no deliberate visible picture abstraction at all. The basically invisible (yet still misguided) tiny unavoidable sharpening present on last year’s ST50 (which appeared on a zone plate test pattern as a strange “four leaf clover” shape in the middle, but basically had no visible effects with real content other than desktop PC use) is gone: with overscan disabled and the [Sharpness] set to 0, the 42ST60 features very clean pixel transitions – just stay away from the [1080p Pixel Direct] mode, which features horizontal sharpening (there is a sort-of workaround that we’ll share later in the review). Assessed with a luma zone plate test chart, only very, very minor moire could be seen around the edges, indicating that the ST60 keeps its hands off the presentation, and lets the excellent PDP component speak for itself. A flat-screen TV of this quality doesn’t need video processing “party tricks” to make it look excellent, and it seems that Panasonic is aware of this fact. Even the default “True Cinema” picture settings stay pretty true to the original source; calibration takes it up a notch.
The wonderful thing about displays which feature outstanding black-level performance (like Panasonic plasmas) is that the image can be both accurately coloured and incredibly vibrant. We’ve seen a lot of LCDs and projectors that try to fake vibrancy by using non-standard wide colour gamuts, but the TX-P42ST60 gives you the real thing.
There is almost nothing left about the picture quality on offer here that we feel could be significantly improved – we could hardly be any happier with what we’re seeing. Panasonic’s plasma panel driving mode is outstanding, producing a very clean image which is free of high amounts of dithering noise. Watching dark scenes in films does reveal a bit of it in the shadows, especially if you calibrate the HDTV to target a higher gamma (for use in a dark room), although it’s nothing we can’t handle (we’re eager to see what the step-up models, with their higher rated gradation, can do, though). The only downside related to Panasonic’s sub-field drive method is that certain combinations of colour and tone, if moved fast enough, can result in some false contouring (the aforementioned “oily skin” effect), but it’s rare, and we still prefer it overall to the noisier but more temporally consistent panel drive mode used by Pioneer’s Kuro plasma TVs (not everyone will agree though – don’t shoot!). The only people we think who won’t like it are those whose eyes/brains simply don’t mix with plasma display technology and its method of building video frames.
Incidentally, line bleed seems to be reduced compared to last year’s ST50. (Line bleed is a phenomenon seen on plasma televisions where luminance changes, for example, white text on a green background, can leave horizontal streaks that span the width of the panel). We say “seems to be” because our comparison here is our resident TX-P50ST50, and the larger size, and indeed individual panel, could account for the difference. Nevertheless, we fed both screens simultaneously with our custom line bleed detection pattern, and the effect was considerably lessened on the ST60.
We took a look at various test patterns on the Panasonic TX-P42ST60B to check out its screen uniformity, and couldn’t see anything that was even worth noting. (For what it’s worth, the 42in ST60 we’re reviewing here is actually a retail set supplied by a store, rather than a hand-picked sample). Our own ST50 did get slightly worse in this regard over time, though, and judging from posts on our forum, we’re not the only ones to have had this happen. The sad truth is that all electronics do degrade over time, and none of us are psychic. Still, our new TXP42ST60 had absolutely no problems at all after we aged it for a suitable amount of time, which bodes well for the future.
There had to be some bad news, right? Here it is: although gaming is still enjoyable on the ST60, its input lag is higher than the outgoing ST50. The fastest configuration is to enable the “Game Mode” and make sure that “1080p Pixel Direct” is disabled. Under this configuration – which is the fastest we could squeeze out of the ST60 – we clocked the TXP42ST60B in as lagging by anywhere between 47ms and 62ms, using the high-speed camera measurement method. Enlisting the more concrete services of the Leo Bodnar Lag Tester, the measurement came out as 74.5ms (it also clocks our old ST50 in at about 47ms, the large discrepancy between this result and our camera method being something we have some theories about, but are still investigating).
As you can see, measuring input lag is not always an exact process, so to get a better understanding, we played some first-person shooter (FPS) games through an HDMI splitter, simultaneously feeding our old 50ST50 as well as the new P42ST60 (by the way, we checked to the best of our ability to guarantee that the HDMI splitter wasn’t adding its own lag, and didn’t feel that it was adding any). The take-home message should be this: this year’s ST is definitely slower for gamers, although exactly how much is difficult to determine.
We tried everything we could to reduce the TX-P42ST60′s lag, including cycling through picture modes, enabling/disabling “1080p Pixel Direct”, changing the “HDMI Content Type” mode… but 47ms was the lowest number we could get. This by no means makes games unplayable, but the buttery-smooth, blink and you’ll miss it responsiveness of the ST50 is not here. We just hope that the step-up series – the GT60, VT60/VT65, and ZT60/ZT65 – can improve on this… although it’d be the first time a higher-end model was had less lag than the mid-ranger so we’re not hugely hopeful. Still, those higher-up models do feature the new Hexa-Core processor… so perhaps the ST60′s slightly decreased gaming responsiveness will be a one-off.
If you’re using a PC with the TX-P42ST60B, you can get full 4:4:4 chroma by using the [1080p Pixel Direct] mode, which on its own will result in large edge halos. These can be defeated by setting the “HDMI Content Type” for that input to “Photo”, although this may have an impact on colour accuracy with some content (it appears to make no difference for RGB content from computers, but changes colour decoding with YCbCr video, like what is commonly output by set-top boxes and disc players).
The Panasonic TX-P42ST60 is another outstanding plasma TV which produces lush, vibrant image quality in normal living room and home cinema environments. For passive movie and television viewing, it doesn’t deviate from the winning formula of 2012′s ST50 series, and in fact improves on it by delivering even better contrast performance, with black depth that’s better still. Impressively neutral colours are present in the out-of-the-box “True Cinema” mode, and a worthwhile increase in accuracy is attainable if you have your ST60 calibrated using the extensive indepth setup controls. The 42ST60 also does away with one of the very mild video processing foibles we pointed out last year, and also now offers expert calibrators more control over the picture quality, for users who want to have their ST60s fine-tuned (which we absolutely recommend for an HDTV of this quality – it deserves it). Colour accuracy was statistically a small step back from last year’s ST50, but not to a visible extent.
If you won’t be interacting with the TV at high speed during intensive competitive fast-paced video game use – that is, if you’re using it for the admittedly more typical television and movie use – then we can’t recommend it enough (if you’re gaming on it, it’s far from a “no go”, but if you’re as sensitive to input lag as we are, you’ll be better served by slightly speedier displays).
Install a Panasonic TX-P42ST60B in a moderately lit, or better yet, dedicated room, and you’ll be rewarded with one of the best HD television-sized experiences you can buy at any price level – the fact that it’s on sale for £900 is a cause for celebration. The revamped Smart TV interface (“My Home Screen”) is neat, and the Touch Pen feature is genuinely fun to use, although it remains to be seen if the novelty will hold for home users (using a plasma screen as a giant whiteboard sounds more like a business feature to us).
We’re now more eager than ever to check out the higher-up GT60, VT60/VT65 and of course, the zenith ZT60/ZT65 series, as well as Samsung’s 2013 plasmas, but they’re going to have their work cut out for them to significantly improve on this in terms of picture quality. But Panasonic, please watch that input lag!
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