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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DanNeely - Tuesday, September 1, 2015 - link
They get enough loaners to keep the review queue in a constant backlog (see periodic comment rage about the review of X, Y, and Z being delayed). If ad revenue ever got to the point that they could hire enough reviewers that they didn't have anything to review at times a shopping trip might make sense; but they don't and probably never will.Even if that did happen, Sony probably wouldn't be the recipient because they've almost entirely abandoned the US market. If you're bound and determined to have one you can get it; but for 99% of the consumers who read the articles and let the ads load (aka the people who actually make the site money) Sony is irrelevant because it's not something they can find in the store.
MrSavage - Tuesday, September 1, 2015 - link
Interesting Dan. Thanks for the insight!Michael REMY - Thursday, September 3, 2015 - link
well, i can believe what i read. you wait for the brand to provide you the device that you review. it is a leak of independence, don't you think ? can't you just buy it on amazon, try it, write your review then get your refund and return the product ?Seriously, for your own knoewledge, you should have test for yourself the last model of sony tablet to win&earn another point of view (better) on samsung tablet or asus zenPad.
IanHagen - Wednesday, September 2, 2015 - link
I'm really glad 4:3 aspect ratio won the battle. It's so much more useful in a tablet.911electronic - Wednesday, September 2, 2015 - link
Nice specification but still i dont know what about battery. It is important for most of the users.DanNeely - Wednesday, September 2, 2015 - link
Page 8 Battery Life and Charge Time. 7 hours on the wifi browsing test is a very poor result.aldenf - Friday, September 4, 2015 - link
Maybe I need to turn in my geek card. I see no benefit whatsoever of such resolutions in an 8" form-factor. The way I use tablets, I prefer the 4:3 ratio. So this is great. I spend far too many hours sitting 30" from my 24" 19x12 IPS, calibrated with a ColorMunki, working in Photoshop and Premiere. With an 8" display, at an 18" distance, I see no benefit above 1280x1024. On the contrary; brightness, performance and battery life suffer significantly. I've used most of what is currently available on the market and don't get the insistence of pushing higher resolutions at 8". I own two 8" tablets; an 800x600 Android and 1024x768 iPad Mini. 800x600 is borderline rough but 1024x768 is pretty good. 1280x1024 seems ideal. Why do we suck up all the marketing baloney? Bigger isn't always better. More isn't always more. It's not the resolution that we discern as better, it's simply that they're usually higher quality displays. Drop the Asus' resolution to 1280x1024, keep the high quality, do a reasonable calibration from the factory, drop the price to $250 and you have a darned nice Android tablet to last a couple of years. Really, what more do we want?nitram_tpr - Wednesday, September 9, 2015 - link
Another vote for widescreen tablets for me, it is all I've ever used (still using a transformer prime). I do watch a lot of medie on my device while I'm travelling / commuting. I tried it on the wife's iPad and got fed up with the huge black bars. Full screening it is like watching an old CRT, so I'm glad there are still the widescreen options out there.To all the people whining and bitching about this tablet, are you actually pissed off because you wanted to buy it, or are you just joining in with the bitch fest?
If it isn't 4:3 don't buy it, end of.
er0k - Monday, September 28, 2015 - link
Hello: My Zenpad 8.0 S is only two days old, out of the box. I cannot seem to charge it. I charged it for many hours yesterday only to find it with a dead battery. I moved it to several different outlets, tried different cables and chargers that work with other devices and worked with it previously, to no avail. It will show the battery charging icon, but does not appear to actually charge. Any ideas? Thanks.System Optimizer - Wednesday, November 4, 2015 - link
er0k,Did you ever get your charging issue solved. Did you try connecting to charge off a computer (if you have USB ports that charge, and the appropriate wire)? Did you hold in the power button and one of the volume buttons to force a reset on the device? (I have an old Archos 80 Titanium tablet, and once I thought it wasn't charging, and was dead, but in reality it was charged and was reporting improper information and the forced reboot resolved the issue). I don't know the z580's reset process, but I expect its something similar.