I got a new phone for christmas, a Sony Xperia XZ1 Compact, to replace my old (well, not that old actually) Xperia Z3 Compact. After using it for a few months, I’d like to share my experiences with this phone.

The predecessor: Z3 Compact

From October 2014 to December 2017, I’ve been a very happy user of the Sony Xperia Z3 Compact. This was a beautiful phone: Small enough to be held and operated with one hand, very nice design, long battery life, yet with the most powerful hardware you could buy at the time. It would have been perfect if the camera was also top-notch instead of just somewhat okayish, but well – if you want a high-end Android smartphone with a smaller than 5-inch screen, you need to get one from the Sony Xperia Compact series. There wasn’t any choice, and any complaints I could have about the Z3 are pretty high-level. There was of course the camera, which showed strong horizontal and vertical grid-like artifacts when used in it’s full 20-Megapixel resolution. But then again, there was a perfectly fine 8-Megapixel mode without such problems; combined with the very well-balanced noise reduction that completely removed all chrominance noise and let the luminance noise look like natural film grain, it was actually pretty darn good, only white balance and exposure weren’t always perfect.

Since performance of the »Z3c« (which I’ll be using as an abbreviation from now on) was still more than decent in 2017, there would have been no need to replace it by another phone. I would absolutely still use it, if it had not started to fall apart: First, the GPS antenna broke. That’s a common problem; the various antennae in the phone all use pogo pins to connect the mainboard to ground plates molded into the case, and the GPS antenna’s ground plate connection failed. The result: No signal, at all. First, wiggling with a USB plug in the USB port helped, but eventually that wasn’t an option any longer, because of problem number two – the SD card slot’s locking mechanism failed, and ejected the card every time when the USB/SD compartment was opened. One time, the card wouldn’t lock in again; I finally managed to get it back in, but from that time on, I never opened that compartment again. I could still use and charge the phone because I had a charger docking station, but still, its days were over – I needed a new phone!

The selection

Selecting a successor wasn’t easy. When I first started looking, the XZ1c (another abbreviation I’m going to use frequently in this post) didn’t even exist. In the end, my shortlist of potential models boiled down to the following, neither of which would fit the bill perfectly:

• Sony Xperia XZ1 Compact (obviously) — more of the same, but less attractive and still sub-par camera (I’ll come to that)
  (the XZ2 Compact wasn’t a thing back then)
• Samsung Galaxy S7 — a little too large, but would perhaps still be OK. No pesky Qualcomm SoC (yay!), but a boring Samsung phone with some questionable design choices (like an absolutely bonkers display resolution only to compensate for the crappy PenTile OLED layout)
  (the successors with their obnoxious huge screens aren’t even worth thinking about)
• Huawei P10 — same thing, but different: a little too large, no Qualcomm SoC, slightly weird camera, quite cheap
  (again, the P20 didn’t exist at that time)
• Google Pixel 2 — not very nice-looking, but boy, that camera! Oh, and that price …
• Apple iPhone 8 — no, just kidding! Android is already a pretty bad operating system, but at least it’s not the utter shitfest that iOS and the whole Apple ecosystem is.

In the end, I didn’t come to choose – I put all alternatives on my Christmas wishlist for my relatives to see, not really expecting them to fulfill this particular wish. I arranged myself with the broken Z3c well enough that I could wait a few months longer. But then, at Chrismas eve, there was that suspicious-looking present that turned out to be an XZ1c. I was very happy – not just that I finally had a working phone again, but also that I didn’t need to make that choice.

In hindsight though, the XZ1c wasn’t necessarily the best option. And now I’ll finally start explaining why …

Design & Handling

Once every few years, there’s a phone model with a design that’s just perfect. The Samsung Galaxy S2 is such a case, or the S7 (non-edge); Apple’s iPhones 4 to 5S were quite beautiful, too, and the Z3c also belonged into that category. Sure, the glass bottom caused the phone to slide a bit on smooth surfaces, but other than that, the design was perfect. But just like Samsung and Apple before them, Sony used a much less attractive design for the successor models. Specifically, starting with the Z5c, the Xperia Compact series gained a lot of thickness. I got used to it quite quickly, but compared to the Z3c, the XZ1c looks really cheap. (However, it’s still nowhere near as ugly as the newer XZ2 Compact.) The case is made of plastic, except for the glass front. The material is bit slippery; I always feared that the phone might slide out of my hand until I put it into a case.

All the buttons and interfaces are where they used to be, except for the Z3c’s pogo-pin charging interface, which is no longer needed because from the Z5c on, the USB port is waterproof and a normal charger can be used without opening any sealed compartments. The USB port is of the USB-C variety, which is still a bit of a nuisance in this day and age where pretty much all existing infrastructure (chargers, cables) is for Micro-B – but that’s really not Sony’s fault, and if they didn’t use USB-C, people would likely complain about them being too conservative. Oh well.

The standby switch is a little recessed into the case, which prevents accidental activation. The ergonomics of it are just perfect. It contains a fingerprint reader, which works well enough that when I just want to look at the lock screen clock, I tend to accidentally unlock the phone, but when I really want to unlock the phone, it often takes a few tries. Overall I’d say the fingerprint reader is a net win, as I’m not forced to do the obnoxious Android 5 unlock finger dance every time I want to use the phone, even though it does get a bit frustrating when the reader needs its occasional three attempts to recognize my thumb.

The camera shutter button, one of the features unique to Sony phones, is present on the XZ1c as well, but it’s really hard to press down. In the case I bought for the phone, which has an additional rubber bumper over the keys, it’s basically impossible to use it: Pressing it half down already takes quite some effort, and pushing it all the way down to actually release the shutter requires so much force that my hand starts to tremble at that point.

Sony still includes a proper headphone jack, and they still care about audio quality, as the quality of that output is just fine in my subjective tests. I don’t have any proper tools for objective measurements, though.

Performance

The XZ1c uses 2017’s top-of-the-line Qualcomm Snapdragon 835 SoC and as a result, Android feels really snappy. I don’t do many CPU or GPU intensive tasks with it, so I can’t really comment on specific performance numbers (and I don’t feel a difference to the Z3c’s Snapdragon 801 either). What I do note, though, is the increase in available RAM (from 2 GiB to 4 GiB) which causes the web browser to reload tabs much less often, and the blazingly fast UFS flash storage. I’ve never seen a phone install apps that fast :) WiFi also seems significantly faster than with the Z3c, but I don’t have any hard numbers for that, as the PingTools app doesn’t like to talk to my iperf server for whatever reason.

The only complaint I have in terms of performance is that the gallery app takes ages to load full-resolution tiles when zooming into an image. The Z3c already wasn’t exactly fast in this regard, but the XZ1c is even half an order of magnitude slower. Let’s just hope that this is some kind of firmware fuckup that will be fixed by Sony at some time.

Display

Owing to the relatively small display area, Sony only puts 720p screens into their Compact models. This seems to be low for today’s standard, but in fact, it’s really not an issue: You have to look very closely to notice individual pixels, and less pixels means less power consumption and more performance. (That’s why the Compact models usually beat their full-sized siblings in 3D benchmarks: Same GPU specs, but only half as many pixels to fill.)

There are three color management presets: normal (sRGB), too colorful (the default setting) and extremely colorful (what Sony calls »super vibrant« mode, or whatever it is in English). I always use sRGB mode to get as realistic colors as possible. The default mode’s color rendition seems to be bearable though; the »vibrant« setting, however, is complete garbage and even squashes dark and bright grayscale tones.

The white point of the display is a bit strange: Sometimes, but not always, it looks too yellow (low color temperature). It might be my imagination, or a software bug, or some weird automatic setting stuff going on, I don’t really know. It doesn’t correlate with any of the usual suspect environmental conditions (ambient light levels, time of day) or settings. All I know is that it’s occurring much less often now than it did when the phone was new – I don’t have an idea whether this is due to me getting used to it, or whether it has actually improved. A big mystery.

The display’s black level is pretty impressive for an LCD: the difference between a black pixel in the status bar and the bezel is only noticeable on careful inspection. The backlight can be very bright, and if this isn’t enough, the firmware enables a high-contrast mode with a lot of sharpening applied. In this mode, text remains somewhat readable even in direct sunlight, even though pictures look like garbage, but at least you can see something in adversarial lighting conditions.

Automatic brightness control was extremely flaky in the first firmware revisions, but over the last few updates, it has been tamed a bit. It’s still far from perfect though; it often sets the brightness too low, something I can’t remember happening that much with the Z3c.
The XZ1c’s combined brightness/proximity sensor is a strange beast anyway: In darkness, a faint, constantly flickering red LED can be seen above the screen, next to the earpiece, even if the display is off. I wonder if this is the most energy-efficient way of implementing a proximity sensor, but so far, I haven’t noticed any bad side effects.

Battery

Good battery life was always one of the hallmark features of Sony smartphones, and the XZ1c does deliver in this regard too: With moderate use, it’s no problem to survive two to three days without recharging. While it is certainly possible to drain the battery in the course of one day, it takes some serious effort to do so. (Or a misbehaving app that constantly runs in the background – I had that once too.)

In addition to the already good battery life, there’s Sony’s custom »Stamina« mode: If the remaining capacity drops below a certain (configurable) threshold, everything that’s dispensable is deactivated and display brightness is reduced to a minimum. Even UI animations become jerky at 15 or 20 fps, either deliberately or as a side-effect from reducing CPU/GPU clock speeds. To my taste, the performance reduction is a little too extreme, as the phone suddenly feels ten years older.

Another nice feature is a »smart« charging mode that should (in theory) slow down the battery’s aging process: The phone observes when it’s typically being charged, and if it’s plugged in and it’s reasonably certain that it’s going to be charged until 7am (because that’s what the user has done in the past, or because an alarm has been set for that time), it stops charging at 90%. The remaining 10% will only be filled up towards the end of the charging phase, minimizing the time during which the battery is fully charged, which Li-Ion batteries generally don’t like.

Camera Features

Photography is one of my few hobbies, so I tend to take this aspect of a phone more seriously than many other people; that’s why I’ll split it across two sections here.

The rear camera is powered by a 19-megapixel Exmor RS sensor, ostensibly an IMX400. This is a very strange sensor indeed, as it contains a DRAM die and a (partial?) ISP directly in the same package. Other than that, it’s a normal backside illuminated CMOS sensor; the only noticeable thing the »stacked CMOS« shenanigans can do what a standard sensor can’t is extreme slow-motion video – more on that later. Apart from the sensor itself, the camera system is rather unremarkable: No dual sensors, or dual pixels, no image stabilization, fixed-aperture f/2.0 lens, but at least there’s some phase-detection autofocus. An HDR mode exists, but its effect is minimal (I can’t see much of a difference even in high-contrast scenes). The front camera is a standard 8-megapixel sensor, perhaps an IMX219PQ.

Compared to the Z3c, Sony’s camera app got a significant update in »manual« mode: It starts up as a Program AE mode (like on the Z3c), but EV correction, white balance, sensitivity and shutter speed can be configured manually if the user wants to. The choice of resolutions is a bit disappointing: It’s either full resolution or 12 megapixels, in both 4:3 and 16:9 aspect ratio, and that’s it. There’s no good-compromise resolution like the Z3c’s 8 megapixels that used to hid the camera’s imperfections but still gave sufficiently high resolution for general-purpose photography; and there’s no low-resolution mode with 2-3 megapixels for when you just want to capture a quick note.

In video mode, four settings are available: 1080p30, 1080p30, 2160p30 and 720p120. For unknown reasons, scene-type detection automatic AE (»intelligent auto«) is always on for video and can’t be deactivated or overridden; at least AE and AWB work well enough that this isn’t an issue most of the time. In 4K (2160p30) mode, the user can choose between H.264 and H.265 compression; all smaller resolutions are always recorded as H.264. The video encoder uses quite long GOPs, which make lossless cutting of captured videos harder than necessary.

The stand-out feature of the camera (that has only been matched by Sony’s arch-rival Samsung just now, at MWC 2018, while Sony upgraded it to higher resolution) is the super-slow motion mode. This captures a short burst (100-something milliseconds) of video at 720p960, i.e. almost a thousand frames per second, albeit with reduced image quality. (The technical trick here is that the frames are actually only stored in the sensor’s internal stacked RAM during the 960-fps burst, and then processed afterwards at »only« 120 fps.) In addition to only capturing a single burst, there’s also a mode that continually captures at 30 fps and records a slow-motion burst when the user taps on the screen; the result is a video that runs normally, but slows down dramatically in selected moments.

There’s also a burst mode for still images that makes use of the stacked RAM: When enabled, the phone captures full-resolution frames at approximately 10 fps as long as the physical shutter button is fully held down, or until the buffer is exhausted (which happens after 21 frames). The images are then saved as individual JPEG files into a directory in internal storage (the SD card can’t be selected as a target for this specific mode), but are treated as a logical unit by Sony’s album application. Other gallery apps will show the separate directories for each burst though.

What’s sadly missing from all of this is a way to capture Raw/DNG images. Sony’s official app doesn’t offer this option, and apps using the Android camera APIs don’t see this either. Even worse: The camera behaves completely different with the Android APIs. The old, deprecated Camera API offers additional resolutions (8 megapixels, 3 megapixels and even some really tiny resolutions like VGA and QVGA), but doesn’t allow Raw capture. With the newer Camera2 API, only the smaller resolutions of 8 megapixels and below are possible, and the image quality is worse than with the Sony camera app (specifically, it suddenly shows chrominance noise which normally isn’t an issue).

Camera Quality

At a cursory glance, photos from the XZ1c look quite good: Autofocus is quick and sufficiently precise, automatic white balance works quite well (a huge improvement over the Z3c), auto exposure only struggles in extreme lighting conditions. Colors might be a bit too saturated, and it looks as if there’s some local contrast enhancement applied, but overall it’s quite OK.

Until you zoom in.

At pixel level, the camera’s results are a mess. This has always been a weak spot for Sony: They build the best image sensors in the world, which are used by basically all high-end phones (except those from Samsung), but yet they don’t manage to get the same level of quality out of their very own sensors that the whole competition does. (This seems to be a common pattern in large companies: The division that builds the chips makes recommendations to the customers on how to use them; the external customers follow these recommendations and get good results, but the products division of the company that built the chip claims to know better and ends up with inferior quality. I’ve already seen this happen before with at least one other company.)

I mean, sure, 19 megapixels are a bit too much for a small smartphone camera. All other vendors tried to go as high as 16 in the past, but in the end they all settled for 12 or 13 megapixels a few years ago and never looked back. Only Sony is still stuck with 19+ megapixels, so we need to accept some tradeoffs in pixel-level quality as a result. But even with that in mind, quality just doesn’t hold up with other cameras, and doesn’t look like it’s the sensor’s fault at all – it’s all about bad image processing.

The Z3c used to emphasize lattice-like patterns when shooting in full resolution. The good news is that the XZ1c doesn’t do that any longer, but all the other problems remained. Specifically, the noise reduction algorithm seems to be totally bonkers: It eagerly blurs or removes fine details, yet the whole picture is still covered with grain, like the visual equivalent of »comfort noise« that’s added to phone circuits. Edges are sharpened heavily, and if the image is not perfectly in focus, slight banding is visible in blurred regions. In darker lighting conditions, the whole image looks like it has been upscaled from a lower-resolution photo, including the noise, which becomes low-frequency grain as a result. That being said, the camera and lens are capable of resolving the full resolution, but only in bright daylight, on high-contrast edges, and with considerable ringing (»overshoot« halos from the sharpening filter). The 12-megapixel mode doesn’t help much, because most of these issues are still visible then; if there was a 6- to 8-megapixel mode, that would be ideal: The Z3c’s image quality was pretty bad in full resolution too, but at 8 megapixels, it was really impressive. With the XZ1c, the only viable option is to use the full resolution and live with the issues.

In the first weeks after the phone’s release, many users complained about extreme lens distortion. With the recent firmware revisions, this seems to be resolved, and I never noticed something like that. Lens distortion correction works just fine for me.

I was quite impressed with the front camera: Sure, it’s worse than the rear camera, but the difference is small enough that I don’t need to think twice before using it in situations where it may make sense.

Software

The XZ1 series was among the first devices to be shipped with Android 8.0, which means two things: First, the software is pretty current, and second, thanks to Project Treble, there’s at least some hope that it will stay this way. Currently, Sony is delivering the monthly Android security updates in time with just two weeks delay. With the regular updates, they often fix (and sometimes break) other things, but they stubbornly refuse to publish any kind of changelog.

The really bad thing, just like with all predecessors up to and including the Z3(c), is that you’re limited to official updates from Sony. While it’s possible to unlock the bootloader, doing so will erase all DRM keys from the device, which is fair – if this wouldn’t make the camera unusable, because for some unfathomable reason, Sony’s image processing algorithms are as DRM-protected as they are mediocre.

Sony didn’t meddle much with the Android UI itself, except for integrating their custom features into the otherwise unchanged Settings app. Older Sony-exclusive features like the Z3c’s »Xpedia mini apps« are gone in favor of Android 8’s built-in split screen mode.

Sony ships its own set of default applications: a custom launcher, gallery, music and video player, e-mail client, you name it. The quality of these is decent; I like the randomized headings in the gallery, and I wonder why Sony’s e-mail client still doesn’t handle deleting mails from a notification properly (on the Z3c, it would often do nothing at all; on the XZ1c, it works, but plays the »new mail« notification sound again), but in general, there’s nothing wrong with them. For the keyboard, Sony uses neither the stock AOSP one nor its own version (as in the Z3c), but SwiftKey; I don’t use it myself, but I think it’s a pretty solid choice.

Unfortunately, Sony also installs a lot of stuff that gets in the way and isn’t easy (or even impossible) to get rid of. For example, »What’s New«, Sony’s own app store kind of thing, which regularly produces notifications about special offers (free apps, themes, crap like that) that can’t be deactivated. Or the »smart assistant« that is so incredibly smart that it warns me that one of my regular alarm clock timers is deactivated right after I explicitly and deliberately deactivated it.

Miscellaneous

The Z3c had stellar GNSS (GPS/GLONASS) reception until it broke, with typical TTFF (time to first fix) of less than 20 seconds indoors and 3 seconds outdoors. The XZ1c is quite disappointing in this regard; reception is significantly worse. Indoors, it usually doesn’t get any signal – the typical GNSS testing tools report no signal at all, not even the tiniest bit. As a result, it’s completely unusable indoors or in vehicles, and even with clear sky, it’s not the best performer.

The other wireless interfaces (LTE, Bluetooth, WiFi, NFC) work as expected.

A very weird part is the vibration motor, which seems to be unusually heavy. Its long spin-up and spin-down times make short bursts of vibration impossible. Instead, it sounds like a miniature jet engine is starting – in most cases, I can hear the vibration better than I can feel it.

Conclusion

The XZ1c is the second successor in a direct line from the Z3c (or the third, if you consider the mid-range Xperia X Compact to be part of the line too). In the three years inbetween, you’d expect a vendor to fix the issues of the older models and emphasize on their benefits. In a way, Sony succeeded at that: The most blatant camera issue has been fixed, and the phone is even faster than before. But along with these steps forward, they didn’t fix all the quality issues with the camera and they even made several steps backward: The case design isn’t as slick as it used to be, GNSS reception sucks, and there are lots of smaller rough edges. Maybe I would have been happier with an S7, P10 or Pixel 2, even though these would be even larger; I’ll never know.

For other people thinking about buying a compact high-end Android phone, there’s just the choice between the XZ1c and the XZ2c (its direct successor) anyway. According to reviews, the latter has some improvements in the camera department, but then there’s the super bulky, ugly design and the even larger screen. If one can live with the sub-par camera and doesn’t need geolocation that often, the XZ1c may still be a viable contender.