The ASUS ZenPad S (Z580CA) Review
by Brandon Chester on August 31, 2015 8:00 AM ESTDisplay: Stock Settings
I often say that a smartphone is just a display you interact with, which makes the need for a high quality screen paramount. This is even more true for tablets, which are quite literally large touchscreen displays that the user interacts with. With tablet displays having peaked in terms of resolution for the time being, manufacturers are now turning their attention toward color accuracy. Flagship devices like Samsung's Galaxy Tab S tablets and Apple's full sized iPads feature displays with an exceptional level of color accuracy, while smaller or less expensive tablets are more hit-and-miss.
Unsurprisingly, the ZenPad's display is very similar to that of the iPad Mini 2 as far as brightness, black level, and contrast are concerned. While Apple has decided to round 7.85" to 7.9", and ASUS has decided to round to 8.0", I'm fairly confident both devices are using the same LCD technology with different backlight arrays. It should be noted that while the contrast ratio is similar in our measurements, when there is ambient light there will be a much more significant drop in contrast on the iPad Mini 2 due to its unlaminated display.
Even if two devices use the same display panel, the color characteristics of each can vary significantly depending on the level of calibration, as well as the spectral range of the LED backlight used. Apple’s iPad Mini 2 achieves a level of greyscale accuracy where errors can only be seen in static content, and is good enough for editing photos and videos without concerns about the accuracy of the images. The ZenPad S doesn’t do as well, with a significant blue shift to most shades of grey. This is also reflected in the display’s high average white point of 7331K. While the ZenPad S doesn’t cost as much as an iPad Air 2 or a Galaxy Tab S2, the Z580CA’s price of $299 is exactly the same as the iPad Mini 2. With that in mind, it’s concerning to see such a gap between the greyscale performance of the ZenPad S and the iPad Mini 2.
Saturation accuracy on the ZenPad S is much lower than what could be achieved with more attention paid to the display’s calibration. With a DeltaE average of 6.2, the ZenPad S is actually less accurate with rendering primary and secondary colors than the iPad Mini 2, despite the latter having a backlight array that only allows for narrow coverage of the blue and red parts of the sRGB gamut. The spectral range of the LEDs in the ZenPad S almost covers the entire sRGB gamut, but the panel undershoots significantly with reds, overshoots with blue beyond 60% saturation, and has various levels of inaccuracy with yellow, cyan, and most of all, magenta. I was really excited to see that the ZenPad S doesn’t suffer from the narrow gamut of the iPad Mini 2, but I was let down when I realized that the accuracy of primary and secondary colors was actually worse than the iPad due to inadequate calibration.
Accurately reproducing color mixtures requires a reasonably accurate gamma, RGB balance for grey shades, and accurate saturations. Gamma on the ZenPad S is reasonably accurate for a mobile device, but the way the display tends toward blue coupled with the inaccurate saturations results in inaccurate color mixtures as well. The ZenPad’s average DeltaE of 5.55 doesn’t compare favorably with the iPad Mini 2’s DeltaE of 3.4 which is imperfect but still fairly accurate. The reason that the iPad Mini 2 ends up being more accurate is because while it cannot be accurate outside its native gamut, within the section of sRGB that it does cover it is very accurate.
As far as the default display configuration of the ZenPad S goes, I’m not exactly thrilled. While it does have a wider gamut than the iPad Mini 3, it ends up being less accurate in every respect due to issues with rendering primary and secondary colors, and a blue shift in the greyscale. Surprisingly, the ZenPad S having a fully laminated display has done nothing to reduce black levels and increase contrast ratio when compared to the non-laminated iPad Mini 2 display, which is an additional disappointment. However, ASUS does provide a few settings to tweak the display, and so hope is not lost.
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uhuznaa - Monday, August 31, 2015 - link
Things are strange right now: You can get an 8" (retina) iPad Mini 2 for $299 and at the same time Android tablets are either a little bit cheaper and really crappy or more expensive and not really much better.If even Apple is struggling now to sell iPads I somewhat doubt that such Android tablets are selling great now...
retrospooty - Monday, August 31, 2015 - link
I dont know about that. I got the $199 Asus Zenpad S 8 a month ago and am loving it. Like all Androids from OEM's, you really need to spend a bit of time to root it and debloat it to make it shine. Debloated this thing flies. For $199 you get an 8 inch 2048x1536 screen, 32gb storage + SD, great build quality, thin, light, great battery life, fingerprint resistant on all surfaces and the CPU is great as well. I was worried about using an Atom chip, but in actual use, it runs perfectly smooth and cool as well. In fact cooler than any Snapdragon device I have ever used. It doesnt get hot at all, ever and I live in Arizona and it's summer. EASILY the best "bang for your buck" available in a tablet right now from any vendor.MrSavage - Monday, August 31, 2015 - link
@retrospooty, I agree with you. People who review a product at a certain price point who want to compare that to products that are about 1/3 more expensive? Or they simply omit the good features like the 64GB onboard storage in this situation, or the front facing speakers, the stylus support or the microSD slot? As if the $299, 2-year old iPad mini 2 with 16GB storage is a wiser choice. If the reviewer wants big battery life, best this, and best that? Then add another $100 to the price of the Tab S2 8.0 for all the features it's lacking that the Z580CA has.BurntMyBacon - Wednesday, September 2, 2015 - link
I agree and disagree. You are welcome to compare it to a product that is 1/3 more expensive, so long as you make it known that that product is 1/3 more expensive. If you stress the comparison against a disparate competitor, then you need to stress the price differential as well. I agree it is disingenuous to point out things that may bring value on one side (display quality, build, aspect ratio, etc.) while ignoring the value adds on the other (SD slot, Storage, Stylus, etc,).Note: My comparison is between two imaginary products and has no bearing on products explicitly or implicitly called out in this article or thread. Comparison was made only to illustrate the point that talking about value distinctions without all of the data is impossible. You may not value the items you left out, but the party you are talking to might.
BurntMyBacon - Wednesday, September 2, 2015 - link
@retrospooty: Given what I've read about the new Atoms, I would probably consider it a boon to a tablet rather than a point of worry. A lot of people seem to be on an ARM or nothing kick. While I was pretty enthusiastic about ARM processors (still am) and I love the competition and what it has done for Intel's low end, I now find there is a lot to like about the Atoms in this form factor as well. Atom got a bad name from its netbook days when it was, frankly atrocious for the application. Now it has matured significantly from a performance / watt standpoint and is running an OS that doesn't run like dirt on low end processors. Of course another nicety of the Atom is its ability to support alternate x86 operating systems if you really want to, but then you have to question whether it is capable of giving you the experience you want. ARM will probably move ahead with its A72 in the near future, but that's a good thing. A little back and forth is good for keeping things moving.BugblatterIII - Monday, August 31, 2015 - link
Do not trust Asus to fix issues!I had (and still have) a Transformer Prime. They never managed to get that working acceptably.
Base your buying decision on how it is at launch, and if they do manage to fix the issues then count that as a bonus.
MrSavage - Monday, August 31, 2015 - link
Did you not get the dongle they created? The Prime was a design flaw. They couldn't software fix their way out of it. If you didn't or don't have the dongle, then I suppose blame yourself.invinciblegod - Monday, August 31, 2015 - link
oh REALLY, an external GPS dongle to do what it should have done in the first place? No, no one should blame themselves, they should blame asus for making a bad product.MrSavage - Monday, August 31, 2015 - link
A design flaw is a design flaw. You can hold onto that issue for the rest of your life if you so choose. You want to miss out of price friendly Asus products because of a design flaw on a second even generation, ground breaking device, then be my guest. I bet you didn't even know about the dongle. The fact is the issue was resolved, albeit a lousy solution. Again, you hold that against them for the rest of your life. That's your odd choice, and if you're okay with it, then so am I.3DoubleD - Monday, August 31, 2015 - link
The dongle fiasco was far from the worst of it though - missing GPS on a 10" tablet was really not a big deal. The Transformer Prime was a complete failure in the end due to the TERRIBLE eMMC that was used. Storage performance just plummeted after a time and while the occasional TRIM helped a bit, it was (and still is) painful to use. Once you are in an app... not so bad. Navigating Android was like watching grass grow... very choppy, laggy grass.It was very sad what happened to the Prime... I remember when I first got it, it blew away any Android device I'd ever used. It is one of two electronic device or computer component purchases I've completely regretted buying. (The other was an AGP Radeon x850XT... that was just outright stupidity on my part)
So that experience colors my view of all ASUS products now. They make some nice looking devices that sometimes have great value... but I just can't help think that they are not fully tested. (As for their PC components, I've had nothing but good experiences)