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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Brandon Chester - Monday, August 31, 2015 - link
Thanks for the feedback. I actually did have a white light box at one point which was used in older reviews, but it fell apart and I haven't been able to make another one yet.MonkeyPaw - Monday, August 31, 2015 - link
Thanks for responding. I've seen it on some other AT reviews as well. We tech nerds like some good product shots to drool over! :pSniperWulf - Monday, August 31, 2015 - link
I bought this tablet at launch. I must say, it is absolutely the best that I've ever owned! Easily beats out all the others, and that list isn't short. Both Nexus 7's, a Nexus 10, 2nd Gen Transformer, Tab S 10.1, iPad 2, iPad 3 and that raggedy ass Shield Tablet. Sure it doesn't have the biggest and baddest of GPUs but it punches above its weight class. The Atom is a strong performer and the storage is awesome!My wife has the 580C and she loves it for what she does.
My only caveat is that you can't disable all of those duplicate Asus apps that you don't really need.
linster - Monday, August 31, 2015 - link
I'm actually enjoying this tablet as well. I've owned the original iPad, iPad 3, Nexus 7 2013, and the Galaxy Tab S 8.4. I do notice that text on some websites just look very light, and could use a bold function. I'm not sure if that's the nature of the site, or the image "improvement" that Asus is doing. I've been thinking maybe it's just my eyes getting weaker as I get older. Browsing is great though, so that's reflected in this review.Sunburn74 - Monday, August 31, 2015 - link
What is the stylus like in real use?MrSavage - Monday, August 31, 2015 - link
At this point, only a couple of Taiwanese websites have reviews/hands-on time with the Z Stylus. If you can translate those sites, it might help. Decent photos though and give a decent idea, but not exactly ideal.SniperWulf - Monday, August 31, 2015 - link
Can't say. Haven't found it for sale anywhere yet. Although I haven't really been looking.deppman - Friday, September 4, 2015 - link
That "Raggedy ass" Shield tablet, released 14 months ago at at $199, destroys the performance on this tablet in almost all aspects. It even has better cameras and a second-generation touch-sensitive stylus. I use one every day (the $299 LTE/32GB model) and can't see any benefit to this tablet in comparison.Jerch - Monday, August 31, 2015 - link
Am I in the minority for holding on to my Nexus 7 (2013) for this long because nothing has yet to surpass it in the crucial areas of battery life, display brightness, and price? It's the perfect beach tablet. Crank that brightness all the way up, and you're good to go for several hours, plus it's so cheap and abused by this point that I don't worry about sand and moisture. I've started to feel it getting slower and choppier, though, so I'd love to upgrade to a [hypothetical] new version!MrSavage - Monday, August 31, 2015 - link
Give me a refresh with phone support and stylus support and I'm 100% happy with that too. I guess that would kill off some of the cheap pricing, but I'd be happy to pay.