ZenFone 2 (5.5-inch) review: Impressive low-light camera performance on this capable handset

Asus however seems to have forgotten about some important bits of the UI design. Annoyingly, there's no 'clear' button for notifications on the lock screen, something other Lollipop phones have.

It's still a pretty good UI, and Asus has done a great job of adding its own touch to Android. The biggest issue I have is that the UI is packed with so many features you'll have to take your time to learn them all, and it feels like the Samsung kitchen-sink approach all over again where there's just way too many features that never really get discovered or used.

Camera

  • 13-megapixel rear camera
  • 1,080p HD video
  • 5-megapixel front camera
  • Low-light mode

Asus put plenty of work into the ZenFones 2's 13-megapixel f/2.0 rear camera, resulting in impressive low-light performance. Called PixelMaster, the phone's low-light mode imaging tweaks to deliver well-lit shots even when there's barely any light.

There are however a few caveats with low-light mode. First, shots taken in this mode are hypersensitive to movement, so you'll need to hold the phone really steady or use a tripod to avoid blurry shots. Also, the resulting image is only 3 megapixels in size, since it uses pixel binning, which combines four pixels into one. This "larger" pixel is able to read more light data, leading to a better low-light shot. The resulting picture is surprisingly bright compared with other phones.

Now, I can testify that this works -- the picture is surprisingly bright compared with say, high-end phones such as the iPhone 6 and the Samsung Galaxy S6 Edge. Do take note this isn't a new feature, it was already present on the first ZenFone, but it seems to have been improved upon.

The front 5-megapixel camera includes a beautification mode, which helps smooth out wrinkles and touches up blemishes on your skin. Not something we haven't seen before in other phones, but still useful.

The ZenFone 2 is capable of shooting full-HD video, and like all smartphones, videos are best shot in bright light for the best performance. During my test, I did find I'd have to tap the screen to refocus, since the autofocus didn't kick in when you transition to a background to a foreground shot.

Check out the shots below to find out how the camera performed in my tests.

Outdoor test shot without HDR. Colors seem a little too saturated here, but HDR (in the next picture) cranks it up a lot. Aloysius Low/CNET

Here the trees at the bottom get the HDR treatment, but it seems way too saturated and warm for me. Aloysius Low/CNET

This close-up shot managed to capture the details while still managing some nice background bokeh. Aloysius Low/CNET

The ZenFone 2 seems to slightly overexpose indoor shots, I noticed this in the other pictures I took. The camera seems to perform better under incandescent lighting. Aloysius Low/CNET

Low-light mode is where the phone really shines, and you'll see in the next picture why I feel the ZenFone 2 is really better for lowlight shots in this mode. Aloysius Low/CNET

asus-zenfone2-lowlightcompetition.jpg
It's not that the shots are bad, but the low-light mode of Asus is a lot brighter (though at the cost of picture size). That said, if you don't use lowlight mode, the image taken with the ZenFone 2 isn't quite as good as the Galaxy S6 Edge or the iPhone 6 Plus. Aloysius Low/CNET

Performance and battery life

Intel's known for its desktop and notebook processors, and its efforts to gain a foothold in the handset business have been decent so far. Earlier versions of its mobile processors weren't as power efficient as ARM devices. But Intel has worked on improving the performance and efficiency with the newer Intel Atom devices. While most of them are better for tablets, the chip maker has spent time on getting its processors ready for mobile.

Given that there aren't many Intel-powered phones in the market right now, it's hard to find a direct comparison with another phone. But going by the benchmark results, the quad-core Intel Atom Z3580 processor inside the ZenFone 2 seems capable of going up against the midrange Qualcomm chipsets, such as the Snapdragon 615 found in the Xiaomi Mi 4i. The benchmark results seem to indicate performance around the same levels.

Now, of course, benchmark results don't tell the whole performance story, but I found the ZenFone 2 to be pretty smooth during day-to-day use. The phone booted up in 44 seconds, and the camera loaded instantly. On games such as Asphalt 8, a hardware-taxing 3D driving game, the phone ran smoothly with nary a hiccup and loading times were zippy.

Based on the numbers below, it would seem that the Intel Atom CPU is achieves similar performance to a midrange Qualcomm chip, such as the Snapdragon 615 on the Xiaomi Mi 4i. The numbers are pretty close on Quadrant -- 24,606 to the ZenFone 2's 22,991, but the ZenFone 2 loses out in the Geekbench 3 test with a score of 2,926 to the Mi 4i's 2,566. On 3DMark the phone does well, but isn't exactly setting the world afire. The ZenFone 2 delivers smooth performance when opening apps and navigating the interface, and while we didn't experience any problems when playing games, don't expect performance to reach the same levels of top flagships like the Galaxy S6 or LG G4.

It seems Intel may have finally gotten its Intel Atom chips right for phones, and perhaps we will see more devices being powered by its processors -- this could open up the market further, as devices no longer need to be limited to ARM chips. However, let's hope a GPU upgrade is in the works for future versions of the chip.

Performance Test

Test 1 Test 2 Test 3 Average
Geekbench 3 2395 2657 2648 2566
Quadrant 23207 22304 23462 22991
3DMark Ice Storm Unlimited 10544 10691 10732 10665

On our continuous video looping tests, the ZenFone 2 lasted 9 hours 33 minutes. That's about four hours less than the Mi 4i (which has a slightly larger 3,120mAh battery) which lasted 13 hours and 18 minutes, it's not really as good. Perhaps video playback isn't really the phone's strong suit, as I found that anecdotally, the phone usually lasts a whole day for me, which is good enough, but still not great.

Call quality

During my time with the ZenFone 2, I had no issues with making calls. Voices were clear and crisp and the other party could hear me clearly as well. The phone's speakers, however, can be a little soft, so you may miss calls or notifications if you're in a noisy place.

4G LTE speeds seemed pretty decent -- the phone was tested in Singapore on SingTel's 4G network, on the Ookla Speedtest app, the ZenFone 2 managed to pull 72.85Mbps download speeds on its fastest run.

asus-zenfone2-speeds.jpg
The phone was tested in Singapore on the SingTel 4G network. Screenshot by Aloysius Low/CNET

Conclusion

While the ZenFone 2 won't dazzle you with a beautiful design or premium materials, the hardware inside is far from lacking.

The Intel-powered phone manages to hold its own, but it's still too early to tell if the ZenFone 2 will start a wave of smartphones using Intel chips. Given its relatively high $299 price (without a contract) for the top end model, Asus may struggle to gain ground against the much cheaper lower-end handsets such as the Mi 4i , which will be sold in the same markets in Asia, and the $200 Samsung Galaxy Grand Prime , available in the US. And if you factor in the $260 Mi Note (though this is still limited to China), the ZenFone 2 may seem a little overpriced.

There is still the $199 option, but it includes only 16GB of storage and 2GB of RAM (compared to the $299 version's 64GB of storage and 4GB of RAM), and since we've only used the 4GB version, we can only speak to its merits.

But interestingly, the $299 price for the 4GB does put it in an interesting position, since the focus recently has been on either great low-value phones and high-end handsets. The ZenFone 2 could still be attractive for those who want near high-end performance without being tied to a contract.

Aloysius Low/CNET

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