The ASUS ZenPad S (Z580CA) Review
by Brandon Chester on August 31, 2015 8:00 AM ESTCamera
While most people will use either their smartphone or a dedicated camera for taking photos, a tablet can be used in a pinch. Some people even make their tablet their primary camera, whether it be because it's their only device, or because they prefer the larger viewfinder that a tablet offers. While many may still find the idea of taking photos with a tablet to be absurd, one need only look at the people around them to see that for one reason or another tablet photography has become a way that some users choose take photos.
The ZenPad S Z580C sports a 5MP rear-facing camera, and the Z580CA bumps that to an 8MP sensor. Since resolution is only one of many aspects of a device's camera system, I've included some more information about the ZenPad S Z580CA's cameras in the chart below
| ZenPad S (Z580CA) Camera Specifications | |
| Front Camera | 5MP (2592x1944) |
| Front Camera - Sensor | Omnivision OV5670 (1.12 µm, 1/5") |
| Front Camera - Max Aperture | F/2.4 |
| Rear Camera | 8MP (3280x2464) |
| Rear Camera - Sensor | Toshiba T4K35 (1.12 µm, 1/4") |
| Rear Camera - Focal Length | 3.0mm (28mm eff) |
| Rear Camera - Max Aperture | F/2.0 |
The ZenPad has a similar camera stack to the ZenFone 2. Toshiba's T4K35 sensor has a resolution of 8MP with 1.12 micron pixels, while the ZenFone 2 used T4K37 which had the same pixel size but a higher 13MP resolution. Lens aperture and focal length end up being the same as the ZenFone 2 as well.
To evaluate the still image quality of the ZenPad S I've taken photos of my standard photo scene during the day and at night, and compared the results to the other tablets that I have available for testing which includes the Nexus 9, the iPad Air 2, and the Dell Venue 10 7040.
It's clear that the ZenPad S suffers from the exact same processing issues as the ZenFone 2. There's far too much sharpening of the image as well aggressive noise reduction. This can be easily seen in any of the foliage in the frame, and in the lines separating the bricks of the school walls. There's also noise across the entire sky, despite this photo being taken with enough light for the camera to shoot at the base ISO of 50. The still image section of my ZenFone 2 review goes into more detail on these issues, and it's disappointing to see that none of them have been resolved. Relative to the other tablets in my comparison, I would have to say that the ZenPad S takes the lowest quality photos. The exposure and color accuracy is much higher than the Dell Venue 10, but the extreme oversharpening and heavy noise reduction makes the image look more like a painting than a photo.
In low light the ZenPad S continues to perform poorly. Low light scenes really make it clear how much of a photo's quality has to do with the quality of the image processing performed. Both the Nexus 9 and iPad Air 2 share a sensor size and resolution with the ZenPad S, and both actually have smaller apertures. Despite this, they both have a better exposure and a much greater level of detail than the ZenPad S. Unlike the day photo test, I would say that the ZenPad S did take a better photo than the Dell Venue 10, but only because I can't even begin to describe the problems with the Venue 10's photo.
Ultimately, the ZenPad S suffers from the exact same issue as the ZenFone 2, which is poor image processing. The color rendition and exposure of images taken during the day makes it clear that the camera has potential, but the numerous issues with the processing produces poor quality images.
WiFi Performance
Like the ZenFone 2, the ZenPad S Z580CA uses Broadcom's BCM4339 WiFi + Bluetooth solution for wireless connectivity. The implementation in the ZenPad S supports two spatial streams on 802.11ac, which allows for a peak theoretical link speed of 867Mbps. However, the ZenPad S has a software problem that makes real world speeds significantly lower than that.
You may be wondering why the ZenPad S can only get a maximum speed of 173Mbps over UDP when the ZenFone 2 with its 1x1 802.11ac goes as fast as 293Mbps. You may have also noticed that a speed around 150Mbps is very similar to devices with 2x2 802.11n WiFi, and that's exactly the problem. The ZenPad S only works in 802.11n mode, a software problem that should have been found in testing long before the tablet actually shipped. I have tested the ZenPad S with an Apple Airport Extreme 6th gen and a TP-Link Archer C7, and the max link speed remains at 200Mbps in both cases. ASUS has confirmed the issue on their end and is aware of it, and so a software fix should arrive for it at some point. Users are, at the moment, just going to have to live with WiFi that isn't even half as fast as it would be if it was working properly.
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BugblatterIII - Monday, August 31, 2015 - link
I wasn't even talking about the GPS; way to jump to conclusions and run a mile with them!And I did get the dongle.
3DoubleD knows what he's talking about (oh and don't forget the interminable hangs on web browsing). MrSavage I suggest you read and learn.
My current router and motherboard are from Asus, no complaints. When it comes to tablets (and probably smartphones) I'd steer well clear. This review mentions some serious issues at launch; they shouldn't exist.
MrSavage - Monday, August 31, 2015 - link
If you recall, the Prime just came out, some hadn't even shipped, and Asus showed of the Transformer Infinity at CES to the dismay of many. The fact is this. That was a ground breaking product, in its second iteration. Nobody else was attempting what they did. Design wise a fail? Sure. But to me, I give full credit for a company that has the balls to release innovative and cutting edge products. They didn't repeat the mistake. Hold a grudge? LOL, go ahead. I'll always praise innovation even if it means problems. Apple antennagate? Happens to even the best companies out there.BugblatterIII - Tuesday, September 1, 2015 - link
The bits they failed on weren't the innovative bits. The keyboard worked very well for example. It was the actual tablet bit where they fell down. They shouldn't have shipped it in that state; they used seriously under-specced hardware and that's probably the real reason they were never able to fix it with firmware.A few years on perhaps they've learned, or perhaps the decision-makers have changed. However the fact they're launching with major issues suggests otherwise, and those who do not learn from history are doomed to take Summer School.
You call it holding a grudge; I call it learning from experience. Same reason I won't touch Belkin.
3DoubleD - Tuesday, September 1, 2015 - link
Agreed. The innovative bits were great. The keyboard with extra battery life - fantastic. Screen was beautiful, even if it was only 720p. Two SD card slots and a full sized USB port - great. ASUS' Android wasn't even too bad (pretty close to stock with some small, helpful additions). But screwing up one of the core components of the system was not a failed innovation, it was poor engineering and quality control. It was also a not a common failure that was unique to the Prime, despite all phones and tablets having eMMC devices. It was such a failure, crippling the usability to such an extent that a recall should have taken place. Hilariously, the previous Transformer tablet has aged far better, while having all of the innovative features, so again, I don't think ASUS should get a free pass because it was 'ballsy'.3DoubleD - Tuesday, September 1, 2015 - link
"It was also a not a common failure, *but* was unique to the Prime..."MrSavage - Monday, August 31, 2015 - link
I registered to ask this question. You guys are known for your "technical" analysis. The issue with reviews is with the basis of comparison or lack thereof. Instead of saying this is the best $299 8-inch Android tablet on the market, you can't and really don't. Instead, you suggest spending another 1/3 of the price for something else!? Or yet get an old, outdated iPad mini 2?What are front facing speakers worth to a tablet user? What is a stylus input worth to a tablet user?
It would seem that the reviewer doesn't know the Samsung Tab S2 8.0. Explain what that extra $100 in price gets you, that's better than the $100 cheaper Android tablet. The point is, expand on a spec basis what makes the extra $100 a better buying option. Perhaps your readers only shop for the most expensive product. In that case, each review will be price based. The most expensive on the market = the best. Thus, a review just explains why the premium cost is worthwhile. To write in the review that looking at the $100 more expensive Tab S2 is worth considering? How about why? Why is that worth it?
DanNeely - Monday, August 31, 2015 - link
*sigh* Up until I saw the display and battery sections I was somewhat interested in this tablet.Is there anyone selling an 8" android tablet that isn't either a cheap wretched piece of crap or fundamentally broken in some way (eg Samsung's backwards buttons, Kindle's lack of Google apps, etc)?
MrSavage - Monday, August 31, 2015 - link
Unrealistic consumer? Wants - long battery life, best display on market. Wants - cheapest price possible. Seriously? If battery life is crucial, there are things called external battery packs. $20 perhaps? Not tied into a device and can be used for other devices. Display issues? Check the specs on the new Tab S2 8.0 and then look at the price. I think I go back to the first two words I wrote in this comment. Something to think about.DanNeely - Monday, August 31, 2015 - link
How exactly do you go from my not wanting a cheap piece of crap to my wanting something as cheap as possible? For that matter I just cited Samsung's tablets as an example of a device with a fundamentally broken mis-feature.I want a good tablet without anything stupidly wrong on it. I'd gladly pay $400 for something like the Tab S2 8 if Samsung didn't insist on ruining all of their Android devices by screwing the buttons up.
As it is, the Android tablet market has gotten worse than the PC laptop market. The latter at least has enough options that, even though virtually every product has at least one item where they either cheaped out one component to something awful to save a dollar on the BOM or made an generally idiotic design option, I can at least find something that doesn't have a flaw that's a show stopper for me. (XPS 13 laptop, the black tape lens cap on the neckbeard/nose hair camera is less noticeable than the tape over a more conventionally placed camera.) I've been on/off looking for an android tablet all summer; but every time I see something to catch my eye midway through the review there's something that triggers an immediate "OH HELL NO!!!" response.
MrSavage - Monday, August 31, 2015 - link
You are simply being unrealistic, that's my point. Android isn't Apple. Go ahead and go spec by spec through the Z580CA and Tab S2 8.0 comparison and then add the extra $100 you would be spending on that new Samsung.If you think for a moment that the Z580CA is a cheap piece of crap, then no doubt why you are without an Android tablet. You are taking this review as the final word.
Battery life can be solved pretty darn easily, unless their is some issue with portable charger and Type-C.
I am curious though, what's the "hell no" aspect of the Z580CA? I hope it's not the wifi which has been reviewed on a firmware that needs updating/tweaking.
Display wise? I think the reviewer has a built in bias against display enhancements. Lots of charts and graphs talking about display. However, do you really think any of those graphs and charts mean anything to the real world, end user? If you are an elite user, then go ahead and look outside of Android and pay double or triple the price for an Apple display.
I hear what you want. You want an Apple quality device with Android OS. I think the manufacturers have tried and failed at that game and it's why price is their primary goal. Perhaps you can hope for a ZenPad Pro or something similar.
Personally? I would rather have a thicker, heavier and even slightly higher priced Z580CA if it meant bigger battery. However, I can easily get around battery life issues. No ideal, but possible.
Front facing speakers are of no value to you? Stylus input is of no value to you?
The bad thing about charts is that a device which is priced 20% to 40% cheaper will be compared against the most premium expensive models on the market. Is it logical to have them all bunched together? Do car review put Ferrari's against Honda in their speed or performance comparison tests? Some comparisons are illogical.