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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System Optimizer - Wednesday, November 4, 2015 - link
I contacted Asus to ask a few questions since I'm contemplating getting a ZenPad S (Z580CA).I asked if the wifi issue Brandon had reported, that he wrote in the article Asus said they were looking into, had been fixed. (I linked the article). The rep wrote back that they had no reports of any such issue. Don't know if that means they fixed it a while back and it can no longer be reproduced/no one is having the problem any longer, if the rep was clueless and the problem is still there and they didn't bother to read your article, or I wasn't taken seriously and the question wasn't passed down the line to the people in the know. Anyone with a Z580CA (or a C for that matter) able to confirm if the issue still exists?
I asked if the enhancement features Brandon mentioned as being annoyances (brightness adjustment, sharpness enhancement, etc) could be disabled, as I'd read a few other reviewers say they could (at least some of them). The rep replied back that they could all be disabled. Before I came home from work and saw that I had a message from the rep I had stopped by Best Buy and taken a look at the Z580C (not the CA) that they had on display, and I went exploring in the settings area. I can confirm that at least the CABC can be turned off in settings.
I asked if there were any plans for them to update the OS to Marshmallow at some point, or how long Asus (in general) tends to keep putting out patches and updates for their Android system (in other words what their company policy is). The rep said they contacted their Taiwan, and said they had no schedule for the next update. Don't know if that means they have an update in the works, and they have no idea when they are going to have it complete, or if it means they don't plan on working on or releasing any updates in the foreseeable future.
Sunburn74 - Thursday, November 26, 2015 - link
Just received a zenpad ca. Upgraded from a nexus 7 2013. Performance difference is night and day. You can install Google launcher to avoid the stupid zen launcher that comes with the tablet. This essentially makes the tablet feel like stock Android. Also whilst not all the bloat can be uninstalled it can all be disabled permanently. The performance really is very impressive. I received simultaneously a Google nexus 6p and the tablet seems to be smoother in performance overall despite the 6p having marshmallow. I think going with the Google stock launcher really makes this tablet much more pleasant to use. Also the side buttons are a little too firm for my taste and require you to use two hands to push the , one hand to hold the device stably and the other to actually push the button.jh20001 - Wednesday, December 2, 2015 - link
I was back in the market for shopping for a tablet as the one I just recently bought into (Lenovo) decided it needed a broken LCD by barely applying pressure to the screen (it was in my cargo pocket, screen facing my leg….and I leaned forward and it applied enough pressure to crack the glass and turn the LCD into all sorts of colors). So after TONS of research and reviews (ie, http://pocinc.net/blog/product-reviews/review-asus... ), I decided to give this one (ASUS) a chance. So far I love it. The screen looks nicer (they claim it is 2K resolution, but it doesn’t look much better than any other awesome tablet…it just simply looks awesome lol but not 4K like the TVs). It’s faster than my other one, has more space than it + has a card slot for more space and hasn’t given me any troubles yet.zero ozer - Tuesday, November 8, 2016 - link
I just bought my zenpad s last week.it was awesome but the only fall is the battery.3.5 to 4 hours in gaming,but I dont mind it for i am in my private practice.but what is odd is the 3 hours charging?why so long?I choose this because i think i was more practical than buying Samsung a with s pen.i wanted a tablet for gaming so I wont need a pen.I dont need a sim card.and choose this than ipad mini 2 cause the ipad mini 2 has may about just 2 more years before it will be outdated.I own iphone 4 thats why i have an idea about apple.with android you can just share it if your unit cannot download the latest apps.I think the unit can last upto 5 years or more with replacement of battery.it's a good tablet.it's just a little pricey for the battery issues.but in gaming and screen,awesome.