Asus ZenFone 3 ZE552KL Review

Asus ZenFone 3 ZE552KL is the first model from the ZenFone 3 series. Presented in the spring of 2016, the new series is Asus's attempt to expand its market reach in the high-end smartphone zone. Originally, the ZenFone series has been created to satisfy budget-conscious users with a quality mid-range smartphone, but while the first generation experienced lots of problems, the second one managed to offer lots of improvements. The third ZenFone series is here not only to offer an upgrade in terms of design and performance but has the more global goal to reserve a place for Asus among well-established smartphone manufacturers. Evidently, it has managed to do that. ZenFone devices have been awarded over 649 significant honours globally, and the Zenfone 3 ZE552KL, which we're currently reviewing, has won the latest d&i award 2016 by iF at COMPUTEX 2016 and the Good Design Award 2016 by the Japan Institute for Design Promotion.

Specifications

Asus ZenFone 3 is built around a 5.5-inch Super IPS+ display with an FHD resolution and 600 nits brightness. It is protected by a Corning Gorilla Glass 3 with 2.5D curved glass edges and oleophobic coating. The same glass protects the back. The chassis and frame are made of aluminum alloy. Inside the body ticks a Qualcomm Snapdragon 625 MSM8953 chipset with a 2GHz octa-core CPU and an Adreno 506 GPU. The SoCs performance is aided by 3/4GB of RAM (LPDDR3, single-channel, 933MHz). The internal storage can be either 32GB, or 64GB. Power is supplied by a 3000 mAh battery with a 5V/2A charger. The model features an advanced camera department. The primary camera is equipped with a 16-megapixel Sony IMX298 Exmor RS sensor with a 1.12 µm pixel size along with a 6-element Largan lens with an f/2.0 aperture. The latter is protected by a sapphire glass. It employs a TriTeck auto-focus system that focuses in 0.03 seconds and includes laser, PDAF and continuous AF systems. The camera also features OIS and EIS for blur-free photos and videos. The software is also advanced and includes a manual mode along with 19 others. The selfie snapper packs a 8-megapixel OmniVision OV8856 CMOS BSI-2 sensor and a 84° wide-angle lens with an f/2.0 aperture. The model supports a wide range of networks, which are market-dependent and include 4G LTE with VoLTE. ZenFone 3 also supports Wi-Fi 802.11 a/b/g/n/ac, Wi-Fi Direct, WiFi-Hotspot, Bluetooth 4.2. It is equipped with a 3.5 mm jack and a USB Type-C port. The device runs Android 6.0.1 Marshmallow with ZenUI 3.0 on top, which includes VisualMaster 3.0, SonicMaster 3.0, and PixelMaster 3.0. For the full list of Asus ZenFone 3 ZE552KL specifications you can check the model's page.

What's in the box

Asus ZenFone 3 is placed in a rectangular box that (in our case) matches its color - the sapphire black, which sometimes looks as a very, very dark blue. On the top of the lid the model's name is imprinted in gold. Inside, in the top level compartment you'll see the device itself, carefully packaged. The set of accessories includes Asus ZenEar with Mic earphones, a Type-C to USB cable, a SIM-tray ejector pin, some documentation (warranty card and user guide), as well as the 5V/2A charger. The latter is the US NEMA-1 plug standard meaning it has two flat pins and no grounding area. This standard is used in the US, Canada and some Latin American countries, and if you reside elsewhere, you'll need a plug adapter.

Design, build and controls

Asus ZenFone 3 combines glass and metal into one, creating a body that is sculpted with precision and attention to the smallest details. The metal chassis is covered with a 2.5D contoured Corning Gorilla Glass 3 on both the front and rear. The shiny surface of the glass is combined with Zen's signature concentric-circle hairline finish, creating a fluid, multi-dimensional look. The glass panels on both sides finish in 40-degree diamond-cut chamfered edges that are 0.88 mm wide. The precision goes even further by creating a 0.37 mm bevel framing the fingerprint sensor and a 0.18 mm ring around the rear camera. The rounded aluminum frame between the two edges is only 6.16 mm thin and the overall depth of the device is 7.69 mm. More importantly, following Zen's philosophy, all parts of the body stick and feel like being one, which brings aesthetic and tactile pleasure. The body is graced by a 5.5-inch FHD display with 2.1 mm thin bezels. It accounts to 77.3% screen-to-body ratio, meaning 77.3% of the total front surface of the device is taken by the display. While the device is well-below average 5.5-inch smartphones in terms of thickness, its width and height fall within average limits and measure 77.38 and 152.59 mm, respectively. At the same time with its weight of 155 grams, Asus ZenFone 3 is one of the lightest smartphones with a 5.5-inch display and a 3000 mAh battery. It is available in four beautiful colors: Sapphire Black, Moonlight White, Shimmer Gold, Aqua Blue. We are reviewing a sapphire black unit. Exquisite build and looks don't remain unnoticed. The model has won the d&i Award at Computex 2016 (iF certificate) and this month it has received the Good Design Award 2016 by the Japan Institute for Design Promotion. Along with Reddot awards, these two form the top three most important awards for design in the industry. The layout of controls is pretty classic. The top frame of the device is where you'll see a 3.5 mm jack and a microphone hole. The bottom frame houses a microphone hole, USB Type-C port and a speaker grille. The left frame is where the dual-SIM card tray is placed, while the volume and power buttons are on the right frame. Above the display, on the front, from left to right, are positioned the LED notification light, earpiece, light and proximity sensors, front-facing camera. Below the display, there's a capacitive navigation bar containing a back, home and menu button. They are not backlit but made of a shiny material visible at all times. On the back of the smartphone, you'll see the laser module to the left of the camera and the dual-tone LED flash to its right. Below the camera is the fingerprint sensor, which has an unusual rectangular shape and a 0.37 mm bevel. The Asus logo is at the lower end of the back. The display has an oleophobic coating, but it actually does not prevent entirely from smudges.

Display

Asus ZenFone 3 is adorned by a 5.5-inch Super IPS+ display. It is protected by a 2.5D contoured Corning Gorilla Glass 3, the same protects the back of the device. The 10-finger capacitive touch display panel has a resolution of 1080 x 1920 pixels, peak brightness of around 600 cd/m², 178˚ wide-viewing angles. The bezels are 2.1 mm thin. The display has a fingerprint and smudge-resistant oleophobic coating supports glove touch and employs a blue light filter for eye care. Asus shares that the display has 60 ms response time, while competitor devices have 80-100 ms response time. The display hardware is supported by Asus VisualMaster 3.0 - a suite of visual enhancement technologies, which includes Asus Tru2Life+, Color Gamut Display and Bluelight filter. The Tru2Life+ technology is actually created for 4K UHD TVs. It optimizes every pixel to provide better contrast and sharpness and employs motion-estimation and motion-compensation (MEMC) algorithms for blur-free videos. Indeed, the peak brightness of our review unit of ZenFone 3 is 615 cd/sq.m. and the smartphone is perfect for outdoor viewing without any doubt. The only other smartphone that we have reviewed and has a similar peak brightness is the Elephone S3. White and black luminance values proportionally decrease with the decreasing of the brightness level from 100% to 0%, hence the contrast ratio remains almost one and the same at all brightness levels - 1235-1270:1, which is a sign of a quality display unit. Another indicator for this is the stable temperature of the white dot. Besides varying only a little at all brightness levels, it is also within the normal range for a smartphone display - around the 7700 K mark. In case you want to tweak your display, you can use the Splendid app or Settings>Display, both open one and the same options, including a color temperature bar, choice of color modes (balanced and vivid), a customized mode, in which you can change the hue and saturation, as well the Bluelight filter bar, which disables the color temperature one.

Brightness	White luminance	Black luminance	Contrast	Color temperature
100 %	615.106 cd/m2	0.484 cd/m2	1271	7649 K
75 %	471.764 cd/m2	0.376 cd/m2	1255	7667 K
50 %	326.256 cd/m2	0.262 cd/m2	1245	7682 K
25 %	177.576 cd/m2	0.142 cd/m2	1251	7745 K
0 %	25.943 cd/m2	0.021 cd/m2	1235	7777 K

The display panel of Asus ZenFone 3 has a traditional striped sub-pixel geometry. By default, the device employs the balanced display color mode and under it, the CIE diagram shows a standard gamut coverage, which is close to the sRGB one with slight deviations in the blue, green and red areas. It remains almost unchanged (the color gamut does not expand further) even if you change it to vivid color mode. Viewing angles are specified as being 178-degree ones, and though colors are excellently preserved, there is a certain loss in brightness, when the device is looked at from aside.

OS, UI and software

Asus ZenFone 3 runs ZenUI 3.0 based on Android 6.0.1. Marshmallow. Well, if you haven't used an Asus device before, the ZenUI will look like nothing else to you. Literally, it is overwhelming. It is designed to be pretty and to provide various tools and options for customization of just about anything installed and appearing on the device. It's a matter of personal taste whether you'd like it or not, but you'll definitely need some time adjusting to it and finding your way around. Let's start with the lock screen. It includes a large digital clock and an animated icon for the current weather in your location. Below this widget three large shortcuts to the Dialer, Messenger, and Chrome are placed. At the bottom right corner is the shortcut to the Camera. By default, the notifications and quick settings appear on the lock screen. Swiping up unlocks the device and lands you at the home screen. It has two and a half rows of apps and folders, none of which is docked. That is, you can move and re-arrange them the way you prefer. The lowest row includes the Dialer, Messenger, App Tray shortcut, Chrome and Camera. The row above it contains a folder with Asus apps, a folder with Google apps, Themes, and Play Store. The top row has a shortcut to the Power & Boost app, which kills all background processes and frees memory, and the MyAsus app. There's a second screen of apps as well that includes ZenFone Care, ZenTalk, and Mobile Manager. You can access the list with apps either by clicking on the App Tray, or by swiping from the home screen to the left or right (works both ways). From Preferences>Home screen (discussed below) you can choose to remove the App Tray icon. A single swipe from the top of the screen brings up the list of notifications. It has a "Tap to manage notifications" option below it and Clear button above it. A second swipe opens the Quick Settings with the most used toggles, brightness level, shortcut to the Settings and a shortcut to the options for changing the Quick Settings themselves. The Task manager can be accessed by taping on the menu button from the navigation bar. If you tap and hold it, it will make a screenshot. The functions of the navigation bar buttons can be managed from the corresponding section in the Settings. The Volume menu is different as well. It includes level bars for system, alarm and media volumes along with a turn on/off function for the Outdoor mode. The Power off menu includes power off, restart and airplane mode options. A single swipe up from the bottom of the home screen brings and extensive menu called Manage Home, which we will describe in the next paragraph. The Manage Home menu contains a total of 9 groups of options for customizing the appearance of the ZenUI. The Apps & widgets group is the first one. It opens an interface that contains all apps and widgets available on the device, separated in tabs. The Apps tab lists all applications in alphabetical order, which appear on successive screens that can be swiped back and forth. The second tab is for the Widgets, which again are listed on several screens. For each tab you have an option to search among apps and widgets, respectively, as well as options for how you'd like to view them, sort, group, lock, uninstall, disable and otherwise interact with them. When you want to go back from one group to the main Mange Home screen the back button leads to the home screen and you have to swipe up again to access Manage Home, which is a bit annoying. The second group is called Home Edit and lets you add, remove, and replace existing desktop screens on your device. The second sub-option is to decrease the size of the icons, the third allows you to change the icons alignment, and the fourth is to choose the type of effect, with which screens open and close. The third and fourth Manage Home groups are called Wallpapers and Icon packs, but once you access either of them you actually access both. This is a single app with various tabs for content that is available online (free and paid) and for wallpapers and icon packs, available on the device. ZenUI Theme is the fifth main group, which, actually, has the same function as the Themes app. Similar to the Wallpapers and Icon packs it provides access to plenty of online themes, which you can download as well as offline themes available on the device. However, there's a DIY (do-it-yourself) option, which allows you to create a theme of your choice. If you like that sort of stuff, you'll definitely have fun with it. The Lock apps group is self explanatory and its options can also be accessed from the Apps & widgets settings described above. Preferences is the name of the seventh Manage Home group. It gives you additional tools for more customization. For starters, you can further change the appearance of the home screen by choosing to remove the App Tray icon and accessing apps by swiping from the home screen only. You can also choose the grid size for it and for the app screens, choose various scroll and transparency effects, etc. Secondly, you can also change the appearance of folders and icons from the Folder/Icon group of options under Preferences. The third and fourth options allow you to manage the App Locks and the Unread counts badge, appearing on app icons. Search settings are fifth in the list and from there you can choose the way you access this feature, the default search engine, etc. Show my ZenUI is a feature, which lets you share with your contacts the current UI of your smartphone. The last options are general and regard ZenUI 3.0. They include a "check for updates" feature, Encourage us - a rating system, which is actually found on every single option available from anywhere inside the device, Feedback & help, and About. After Preferences, you'll see the group for all Settings, which can also be accessed from the corresponding app icon and the shortcut from the Quick Settings. The More group of options includes the typical set of ZenUI updates, Show my ZenUI, Encourage us, Feedback & help. Once you open the Settings menu, things will look more familiar to you. It follows the general outline and includes the four main groups of options - Wireless & networks, Device, Personal, and System. Of course, you can expect more customizations here and many of the settings are regrouped, re-arranged, new ones are added and others are removed. Let's start with the Wireless & networks. It provides more options than standard and shows them in a slightly different way that you might have used to with the data usage and SIM card settings being brought a level up for quicker access. Call settings is also placed at the top level as an additional feature. The More... section includes three new features - Emergency broadcasts, Digital media Sever (you can share media with other devices) and PlayTo (let's you connect the device to a wireless player). Being a media-centered device, it is no wonder that the ZenFone 3 has more extensive options in this regard. Device is the second main group of settings and it starts with the Display options. It contains the usual settings for the brightness level, font size, wallpapers, and a Daydream mode, which is slightly altered. However, ZenUI 3.0 also allows you to change the font-style and contains a whole set of options for tweaking the display. You can access them either from Display>Screen color mode, or from the Splendid app, which is actually the same thing. You also get the usual Sound & Vibration, notifications and DND mode settings. There's a separate Asus Cover option, which manages your phone's behaviour if you use an Asus cover for it. Storage & USB, Downloads, Apps management and Memory is something you're already familiar with, so let's roll to the ZenMotion. In its essence, this is a whole set of touch and motion gestures, which once activated should provide more ways of smart somatosensory interaction with your smartphone. It also includes a One Hand Mode, which can also be accessed from the corresponding toggle in the Quick Settings list. Another interesting feature is the Asus Customized Settings. From there you can choose which functions the menu button should perform. You can also switch on a glove mode that increases the sensitivity of the display, while you're wearing gloves. It is under this section that you'll find the Quick Settings options as well as the Game Genie Settings. The latter is a brand-new feature in ZenUI 3.0 and activates an in-game tool bar that will improve your gaming experience. You can summon the pop-up search window to hunt for tips as you play, use the booster feature to speed up the action, or broadcast your gameplay live via YouTube or Twitch. The Device group of options includes two other sets called Battery and Power management, but these two will be discussed in detail in the Battery section of this review. The third main group of settings is called Personal and is very large. It starts off with the Themes options, which does what the Themes app does. It is followed by the Lock screen options, including types of lock, theme, wallpaper, animations, widgets, quick access. Actually, the latter allows you to remove entirely the shortcuts from the Lock screen. However, if you find such a feature useful, you can also choose to place shortcuts to other apps. Location services is self-explanatory and is followed by Fingerprint management. Setting up a fingerprint ID is very easy, the sensor is extremely fast. You can save up to five IDs and assign to them various functions besides unlocking. There are also two interesting modes - Easy and Kids mode. The first one changes the UI to show very large font and icons, so people who are visually impaired can interact easier with the device. The Kids mode looks like being a fun one and you can activate it, if you allow your children to play with your smartphone. The Security settings are standard and include the familiar Smart Lock, which allows your device to remain unlocked near trusted places, devices, voices or your body. The Language & input set of options is enriched with ZenUI keyboard, which is the default one in the device, and options for the behaviour of the navigation buttons. There's a special section for Screenshot settings and, of course, there's a Backup & reset menu. The fourth and last group of settings is the System one. It does not offer surprises and contains Date & time, Accessibility and Printing options, all of which are standard. There's a separate ZenUI Instant Update function, which also appears in the options of any app installed in the device and is used to check for app updates. It is followed by a System updates menu and the About section, which, besides all else, contains a shortcut to System update as well, device status, and legal information. ZenUI is actually a major overhaul of Android. It has not only changed the appearance and behaviour of screens, folders, and icons, but has also added very extensive options for customization and includes a number of Asus-developed apps, which serve as a means to deliver rich media content to ZenFone 3 owners. The Dialer and Contacts are actually two tabs in one and the same app, which also has a third tab for Groups. They look standard, but the developers have added more options for customizing the dial pad, which can take up the whole screen, or be shrunk to its original size, or appear with a dark theme. There's a convenient speed dial list, in which you can add your favourite contacts, as well as a shortcut to the Call settings. There's a Voice search option among contacts and conversations. Besides all usual editing options for every contact, you can also change the cover photo. The Messenger is standard, too, but works with the ZenUI keyboard, which offers plenty of tools and customizations as well, including keyboard resizing and style, an additional keypad for text editing, and toolbar settings. The File Manager is also redesigned in ZenUI's style and contains some additional functions as wireless PC-file transfer, Hidden Cabinet (private files accessed only with a PIN code set by you), Storage analyzer, and Recycle Bin. The Calculator is entirely re-designed and contains a standard calculator, unit and currency converters as well as shortcuts to the Flashlight, File manager and Clock. The latter contains the four main tabs for this app - clock, alarm, stopwatch, and timer. However, its appearance is entirely changed. The clock tab also contains information about the location and weather, which can be removed, a shortcut to the night mode, the weather-only information and an option for changing the location. ZenUI developers have opted to place as a separate shortcut the Power & Boost, appearing on the home screen only. This is actually the Clean all function, which kills all background processes and frees memory. This Power & Boost function is actually a minor part of the elaborated Mobile Manager app. It contains a scanner that monitors battery and RAM performance and checks the device for security threats and potential options for optimization. It has a Data usage section, Boost feature, Notifications management (accessed from the list with notifications as well), a Cleanup feature, Privacy & Security, and App Permissions. The Power Saver is an integral part of the Mobile Manager and is explained in detail in the Battery section of this review. ZenFone 3 features other useful tools such as a Sound Recorder with options for the recording quality, a laser ruler, which uses the rear camera and laser module, and the Asus Share Link app, which is a tool for sharing files with other nearby Android devices or PCs. Being a media-centered smartphone, ZenFone 3 is equipped with two interesting apps called PhotoCollage and MiniMovie. Both apps allow you to tinker with the photos you have already made by making various creative photo collages and movies with them. There are plenty of stickers and photo effects to choose from. The apps are intuitive and playing with them is definitely fun. The Quick Memo app is definitely interesting as well. You can choose either to write with your fingers or use a keyboard. Whatever you write in a note can be further edited, so everything is organized and quickly accessed. You can also use it together with the Do It app, which is basic list of to do tasks, which can also be app-related. Splendid is the name of the app, which allows you to tweak the display. It includes a color temperature bar and a choice of screen color modes: balanced, vivid, and customized. The latter allows you to change the hue and saturation to your liking. There's a Bluelight Filter as well, which disables the color temperature bar. The Weather is another pretty app created by Asus. There three other apps for ZenUI users, all of which require a ZenUI account, - ZenCircle (a social media service), ZenFone Care (includes tests for all main functions of the device), and ZenTalk (a type of chat service). ZenUI developers have also included a MyAsus Service Center app, which provides you with direct access to Asus support 24/7.

Networks, calls and connectivity

Asus ZenFone 3 features a dual-SIM card tray with 4G/3G support. It can house either two SIM cards (micro- and nano-), or a micro-SIM card and a microSD card (up to 2TB) for additional storage, when needed. The device works with 2G GSM (850, 900, 180, 1900 MHz), 2.5G CDMA 800 MHz, 3G TD-SCDMA (1880-1920 and 2010-2025 MHz), 3G UMTS (800, 850, 900, 1900, 2100 MHz), 4G FDD-LTE (700, 850, 900, 1800, 1900, 1700/2100, 2100, 2600 MHz) and 4G TDD-LTE (1900, 2300, 2500, 2600 MHz) networks. Network-support is market-dependent. Download 4G speeds are Cat. 7 ones (up to 300Mbps), VoLTE is supported as well. Reception and call quality have been excellent at all times during our test period. The model also provides extensive wireless connectivity options, including Wi-Fi 802.11 a/b/g/n/ac, Wi-Fi Hostpot, Wi-Fi Direct, and Bluetooth 4.2. All these features work like a charm. The device packs a USB Type-C port and supports GPS, Glonass and BeiDou, and during our test, it managed to detect a good number of satellites from all three systems with excellent accuracy.

Performance

Asus ZenFone 3's hardware is based on a Qualcomm Snapdragon 625 MSM8953 chipset. It includes a 2GHz octa-core CPU and an Adreno 506 GPU. The system-on-chip is made following the 14nm FinFETs process and its goal is to provide a balance between performance and power efficiency. In fact, it provides 35% improvement in power efficiency compared to its predecessor - the Snapdragon 617. At the same time the Adreno 506 GPU supports the latest APIs, including both DirectX 12 and OpenGL 3.1, which means you should not experience gaming issues, unless you run very heavy graphics. Actually, ZenFone 3, together with Samsung Galaxy C7 is one of the first smartphones to employ this SoC from earlier this year. The device managed to score 62586 points in AnTuTu, a result, which is very good having in mind that Xiaomi Mi Max and Xiaomi Redmi Note 3 Pro score more than 70000 points and are based on a Snapdragon 650 MSM8956 chipset. Moreover, if you compare the PCMark Work performance results, the ZenFone 3 outperforms both Mi Max and the Redmi Note 3 Pro. The model has two variants in terms of RAM and storage. The first is with 3GB of RAM and 32GB of storage. We are reviewing the second variant with 4GB of single-channel, LPDDR3 RAM clocked at 933MHz and 64GB of eMMC storage, expandable with up to 2TB. Asus also offers 2 years of free 100GB Google Drive space. The RAM is generous enough and despite being of an older generation, it manages in helping the device run swiftly and smoothly. The storage also performs excellently, according to both the PCMark Storage and Androbench tests. As long as it concerns the on-board sensors, the ZenFone is equipped with an accelerometer, magnetometer, gyroscope, gravity sensor, step counter and motion detector, light and proximity sensor. On the back, below the camera module is placed a fingerprint sensor made by FPC. Its structure is as follows: FPC + sensor IC + diamond cut + smooth coating. It provides 360-degree recognition and can store up to 5 IDs. Adding and managing fingerprint ID(s) is very easy and besides for unlocking the device, you can use them for authorizing purchases, answering a call, snapping photos or just launching the camera app. The module is very sensitive and unlocking is extremely fast even from a switched-off screen.

Cameras

The camera department is ZenFone's series main selling point. ZenFone 3 arrives with the latest PixelMaster 3.0 technology, which in its essence is a combination of advanced hardware and optimized software fro DSLR-like shooting experience. The camera application is strongly modified to suite the camera's advanced capabilities. The home screen of the app contains a shutter button, a video recording button to its left and a shortcut to the manual mode on its right. There's a shortcut to the list with photos and to the one with various modes. PixelMaster 3.0 includes 20 different shooting modes - Auto, Manual, Beautification, HDR Pro, Super Resolution, Children, Low Light, QR Code, Night, Depth of Field, Effect, Selfie, GIF Animation, Panorama, Miniature, Time Rewind, Smart Remove, All Smiles, Slow Motion and Time Laps. The Manual mode lets you adjust the focus, shutter speed, ISO, exposure value (you can even achieve 32 seconds long exposure), and white balance. It also contains a Histogram feature, which can help you determine the correct exposure for your photos. The Super Resolution mode burst captures five 16-megapixel photos and combines them to create one photo with the equivalent resolution of up to 64MP. The Depth of Field is created if you want to achieve beautiful bokeh effect on your photos, while shooting close-up objects. The Low Light mode increases light sensitivity by up to 400%, using pixel-merging technology to merge four adjacent pixels into one. The Smart Remove removes unwanted moving objects from the background. Children mode plays fun tunes to grab your kids' attention and once detected it manages to snap a photo in mere seconds. From the home screen of the Camera app you can also choose a preferred flash and HDR mode as well as directly access the camera settings, which are quite extensive, too. For example, you can further optimize the photo by selecting a manual mode, which gives you access to changing the contrast, saturation, sharpness, noise reduction, backlight and detail optimization. You can also change the metering and focus modes, change the white balance and exposure values for videos, too. The settings for the rear and front camera differ slightly and include options for both shooting photos and videos. The two cameras have a Beautification mode, which includes skin tone adjustment, cheeks slimming, eyes enlargement, makeup, blush effect, etc. There are also plenty of editing options after you take a photo. There's an additional beautification mode, a shortcut to a rotate function, while the list with editing options includes a choice of filters and stickers, cropping, straightening, and otherwise adjusting the photo as well as tweaking the autocolor, exposure, vignette, contrast, etc. You can share any via all available apps on the phone, even send it to a paired device like a TV, for example. There's a spacial information shade about every photo, containing data about its properties.

Primary camera

Asus ZenFone 3 is "built for photography" and indeed, its camera department is feature-packed. For starters, the primary shooter is equipped with a 16-megapixel Sony IMX298 Exmor RS sensor with a 1.12 µm pixel size along with a 6-element Largan lens with an f/2.0 aperture. The latter is protected by a sapphire glass. More importantly, the camera employs a subject-tracking TriTech auto-focus. It includes a 2nd generation laser AF system, an advanced phase-detection AF system, and a continuous AF one for movement tracking. Furthermore, the camera boasts optical image stabilization (OIS) and electronic image stabilization (EIS) for blur-free photos and videos, respectively. More specifically, the OIS functions across all four axis and is aided by an 8-direction OIS compensation and 4 stops OIS stabilization. At the same time, the EIS functions across thee axis and includes 6-direction EIS compensation. This advanced stabilization system will allow you to use very low shutter speeds in low light conditions and still make good photos, which is otherwise impossible. Another important feature of the ZenFone 3 camera is its excellent color reproduction. It combines a deep trench isolation technology (DTI) with a color correction sensor and low-light enhanced ISP. DTI prevents photons of light from leaking from one pixel on the sensor to another, meaning details and definition will be better. The color correction sensor detects unusually-lit subjects and makes them look natural in the photo. You can also enjoy several advanced functions, mentioned above, such as the HDR Pro with real-time preview feature and Super Resolution, for example. Finally, the dual-LED Real Tone flash provides a very natural illumination for more realistic photos. The camera makes photos with a resolution of 4656 x 3492 pixels and shoots 4K videos at 30 fps. For the latter it applies High Efficiency Video Coding (HEVC) to keep your 4K UHD file sizes to a minimum without sacrificing quality. Other smartphone that we have reviewed and have the same Sony IMX298 sensor are the Xiaomi Mi 5 Standard Edition, OnePlus 3, and nubia Z11.

Secondary camera

Asus ZenFone 3 features an 8-megapixel front-facing camera, equipped with an OmniVision OV8856 CMOS BSI-2 sensor and a 84° wide-angle lens with an f/2.0 aperture. It makes photos with a resolution of 3264 x 2448 pixels and can capture FHD videos at 30 fps. Other smartphones that we have reviewed and have the same sensor for their front camera are the ZTE Axon 7 and the Zopo Speed 8.

Audio

ZenUI does not offer a special music player. It utilizes Google's default one, which besides several tools for arranging and playing files, offers nothing else. However, there's a special app called AudioWizard 3.0 (powered by ICEpower) part of Asus SonicMaster 3.0 technology - a combination of optimized software and hardware for improved audio performance. It contains 6 pre-set audio profiles. The Smart one is witched on by default and cannot be altered. The Outdoor one cannot be changed, either, however, the other four profiles can be edited. They include Movie, Gaming, Music, and Vocal. For each you can adjust the volume, bass, treble, switch on/off dialog enhancement and set equalizer properties (it is flat for all profiles by default). ZenFone 3 is equipped with a new audio chamber powered by Smart AMP, which increases the sound pressure level to 94.5dB SPL, lowers the resonance frequency and reduces bass total harmonic distortion. According to specifications, the device is able to play back 192kHz/24-bit audio that is 4 times better than CD quality. There's a dual internal mic with ASUS NoiseZero Talk Technology and, of course, the company's signature 5-magnet speaker, which has been introduced with the ZenFone 2 and is driven by a powerful NXP Smart AMP. However, the new one is 20% louder, extends low frequencies by 17% and produces 42% fewer distortions when the bass is increased. Subjectively speaking, the sound through headphones and from the speaker, does come out very good. However, we have detected a frequency boost at 3kHz, which to our opinion is made on purpose, but we could not find a way to disable it, so it rates as Poor, influencing the overall result of the device to be Good. Actually, this is the first smartphone we've tested with a result lower than Very good. At the same time noise levels are Excellent, which is a very rare quality. THD + Noise is rated as Average and the rest of the parameters are very good. We do our audio test by using the TASCAM US-2x2 audio interface and the RightMark Audio Analyzer software.

Test	Value	RMAA rating
Frequency response (from 40 Hz to 15 kHz), dB	+4.32, -1.81	Poor
Noise level, dB (A)	-95.5	Excellent
Dynamic range, dB (A)	92.7	Very good
THD, %	0.0079	Very good
THD + Noise, dB (A)	-78.7	Average
IMD + Noise, %	0.010	Very good
Stereo crosstalk, dB	-83.5	Very good
IMD at 10 kHz, %	0.016	Very good
General performance		Good

Battery

As mentioned earlier, Asus ZenFone 3 has a special app called Mobile Manager. It contains many tools for optimizing the performance of the smartphone and one of them is the Power saver. It contains a scanner, shortcuts to main functions that consume power, several pre-set battery saving profiles and two smart switch toggles for additional convenience. You can run the scanner at any time and it will come up with suggestions what can be optimized, so the device could save more power. The pre-set battery saving profiles include Performance, Normal, Power saving, Super saving, and Customized. You can change the settings only of the Customized mode and these the brightness and networks options. The Power saver can be accessed from the Power Management settings as well. It also provides you with an option to auto-start the manager. Of course, you also get the standard Battery monitor with shortcuts to the Power saver and the Battery optimization. Asus ZenFone 3 is equipped with a 3000 mAh Li-Ion, non-removable battery, coupled with a 5V/2A charger. The latter is the US plug standard, so you'll need a plug adapter if you live outside the US, Canada and some Latin America countries. The graph below demonstrates the time, needed for the battery to charge in full from 0% to 100% (the yellow line). Our review unit needed almost 2 hours to charge completely. It started charging rapidly right from the start and 50% of the charge were reached in 35 minutes. Another 17 minutes were needed to reach 70% of the charge, when the speed started slowing down. The next 10% to 80% needed 13 minutes and the charging speed slowed down even more. The last 20% to 100% needed 55 minutes. The red line in the chart depicts the battery temperature during charging. When the process started, the temperature was 28°C and gradually increased to 36°C. At 70% of charge it started decreasing and reached 25°C at the end of the process. In addition, ZenFone 3 showed some serious battery stamina during our test period and the PCMark Work battery life test, which showed almost 10 hours (9 hours and 52 minutes to be exact). This is an excellent result for a smartphone with an FHD 5.5-inch display and a 3000 mAh battery. As usual, the test has been performed with the display's brightness calibrated at 200 nits as per Futuremark's recommendations.

Final thoughts

Asus ZenFone 3 ZE552KL is definitely worth its money. It has a high-end design, solid build and a very bright display. The battery shows some serious stamina, turning it into a very reliable device. The Snapdragon 625 chipset might not be the top one, but it does a great job with day-to-day tasks and entertainment, while preserving battery life. At the same time the camera department is one of the most sophisticated on the market and is ready to compete with a lot more expensive models. All in all, this model is the perfect choice for everyone looking for a quality smartphone at an affordable price.