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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PixyMisa - Monday, August 31, 2015 - link
I have two Nexus 7 2013s (one died and wouldn't charge any more, but a wireless charging pad brought it back to life).Still holding on and waiting for something better that doesn't cost three arms and a leg.
I also have an Xperia Z Ultra that I picked up cheap. That's not bad, but a little on the small side for tablet use.
Sunburn74 - Monday, August 31, 2015 - link
Does Anandtech plan to update the review once a stylus is available? For some of us, the stylus input would be a real deal maker (or breaker if it is subpar).Brandon Chester - Monday, August 31, 2015 - link
I specifically asked ASUS to send the stylus and cover if they could, but all I got was the tablet. I have to send this back so I doubt I'll ever be able to look at the stylus. I really wanted to.vladx - Monday, August 31, 2015 - link
What nonsense is this about the camera? The day photo definitely looks the best along with S6 Edge one. Saying the iPad one looks better is a joke.The rumours are true, this site is more and more biased by each day passed.
Brandon Chester - Monday, August 31, 2015 - link
I don't know if you viewed them at full size or not but ASUS's camera processing has been widely panned by pretty much every site that looked at the Zenfone 2, and it is literally unchanged here. If there's some level of bias there then it must exist at every tech site ever.The image quality is not even remotely comparable to the shot from the S6 Edge. A good area to examine is the walls of the school, they're completely destroyed by heavy noise reduction to the point where the lines start curving and shifting. It's just not a good image.
DanNeely - Tuesday, September 1, 2015 - link
It's really that the problems are only obvious in the full size image. The resized images in the gallery aren't large enough to see the problems.This's a sitewide comment, and not directed at you personally; but people who look at the full size images as well as the ones in the gallery are probably in the minority. I think a set of 1:1 crops of a detail area or two that make things like the destructive processing the Asus does readily apparent would really make problems more apparent.
eek2121 - Tuesday, September 1, 2015 - link
I didn't even finish reading the first page of this article and I thought to myself...ASUS made the nexus 7. Why the hate?Michael REMY - Tuesday, September 1, 2015 - link
as Anandtech still continue to ignore sony xperia tablet, i can not consider seriously this review of the asus zenpad. i trust all the review of Anandtech else the tablets ones! I hope one day you could try or review the xperia z3 compact tablet or even the xperia z4 tablet because it changes all the done and the way to judge the other tablets on the market.DanNeely - Tuesday, September 1, 2015 - link
It's not AT ignoring the Sony Tablet. It's Sony ignoring the tech press. AT (among others) have regularly asked for review samples of various products. Sony's almost never willing to provide them. As a result they get next to no press coverage beyond demos at big shows and product release announcements. That's entirely on them.MrSavage - Tuesday, September 1, 2015 - link
People running big websites aren't capable of buying a review unit off a store shelf? Imagine that. Having to pay for a review unit? Perhaps giving it away later as a giveaway contest? Nobody knows about tax write offs? Sure, if it's not free then we don't review it. If it's the best tablet on the market who cares. We won't inform our site visitors of that great product because there was no freebie sent out. Credibility wise, I would not be saying this is great or the best because I chose not to review other top tablets because I didn't get a free one in the mail to review. I wish sites were open about the bias or friendly handshake agreements. The best tablet of the free ones sent out to big websites. Not the best, but just the best from the ass kissing companies who sent out review units. Sad excuse in my books. I call it a disservice to my visitors if that's my mentality.