For what seems like the first time in ages, Sony is announcing a trio of flagship phones at the same time. From big to small, we've got the Z5 Premium, the Z5 and the Z5 Compact. The trio share many attributes, but thanks to one spec, the Premium is by far the most interesting.

The world's first 4K phone display

I'm totally besotted with the Premium's display. It's got a truly ridiculous, world-beating 5.5-inch 4K (3,840 x 2,160) panel, with rich colors and deep blacks. We'll need to spend more time than the few hours we've had with the new lineup to give a proper verdict, but right now we can say for sure that it looks great. I'm not sure I want a 4K display in my phone, but I am sure that the allure of an 806-ppi display will be enough to win some over. Sony's thrown down the gauntlet, and at least in pixel density, the Z5 Premium is the phone to beat.

Unfortunately, Sony's saved all of its new screen tech for the Premium, with the regular Z5 retaining the same 5.2-inch 1080p unit as the Z3 and Z3+, and the Z5 Compact getting a 4.6-inch 720p display.

Apart from their displays, the devices are almost identical.

As far as specs go, though, the displays are pretty much the only things distinguishing the Z5 Premium from the Z5 and Z5 Compact. All three have Qualcomm's Snapdragon 810 processor inside, up to 32GB of internal storage (expandable by microSD), high-res audio chips and "up to two-day battery life." That's a cute way Sony found to say "you only need to charge this one once a day." How they eke out that battery life differs of course, with the Premium having a 3,430mAh battery, the Z5 a 2,900mAh and the Z5 Compact a 2,700mAh. The only other differentiator is RAM: The Z5 Premium and Z5 have 3GB; the Z5 Compact only has 2GB.

The same, but different

The Z5s' power buttons house fingerprint sensors.

If you've seen any Sony phone made in the last couple of years, I'm sure you've already noticed the Z5 family is a very familiar one. Sony's "OmniBalance" design theme has been knocking around since the Xperia Z1, and it's really difficult to get excited about: They're rectangular slabs with clean lines; they're waterproof; and they're uncomplicated. That said, this is probably the tightest iteration on that theme. The Z5 Premium and Z5 both feel very polished, with carefully considered color schemes and materials. The Z5 Compact feels sturdier and a little chunkier, but not necessarily in a bad way.

The Z5 Premium is available in black, gold or chrome, all with a mirrored glass back, while the Z5 has white, black, gold and a subdued green, with a frosted glass back. Sony's clearly targeting the younglings with the Compact, especially with some of the bright and "fun" colors. It comes in the usual white and black, but also vibrant yellow and coral (pink) -- again with frosted glass at the back. Of course they're all different sizes too; The Z5 Premium has a 5.5-inch display and is 7.8mm thick; the Z5 has a 5.2-inch display and is 7.3mm thick; while the Compact has a 4.6-inch display and is 8.3mm thick.

The Z5 Premium in chrome makes for a very effective mirror.

I think the yellow Z5 Compact is probably my favorite of the bunch; the bright color wrapping around the edge of the black display frames the device really well. The green Z5 is also kinda classy looking, and it's a nice step away from the staid colors we're used to from flagships. Also, big shout out to the chrome Z5 Premium, which is essentially a mirror with a phone attached to the back. It's ostentatious; it's ridiculous; and it's impossible to keep clean, but I kinda love it.

So all these new Xperias are familiar, but changed. The same, but different. Those coming from a previous-generation Z will notice how nicely this latest bunch feels to hold, as well as some neat design additions. There's now a little "Xperia" wordmark etched into the phones' metallic sides, and the series' small circular power button is no more, replaced by an oval-shaped button that somehow squeezes in a tiny fingerprint reader.

Taking care of number one

All three phones share the same camera setup.

Sony's new sensor is exclusive to Xperias, for now.

Sony's image sensors are everywhere. Of course you'll find them in the company's own smartphones, mirrorless and SLT cameras, but they're also in high-end Nikon and Fujifilm models. Not to mention flagship smartphones like the Samsung Galaxy S6 and LG G4. Put simply, they're considered some of the finest in the business, and one of the increasingly few areas that Sony is a market leader in. Not all sensors are created equal, though, and this time, Sony's keeping the best smartphone sensor for itself. All of the Z5s have a 1/2.3-inch Exmor RS 23-megapixel image sensor. It's brand-new, and Sony says it'll be exclusive to Xperias, at least for a while.

Click image for original 7MB file. Shot by Sony at f/2.0, 1/2500s, ISO 40.

This fancy new sensor is backside illuminated and has embedded phase-detection pixels. It's housed in Sony's first mobile camera module with a closed-loop actuator, and in front of the sensor is a new six-element 24mm lens with a wide f/2.0 aperture. If you're unsure what all of this means, I'll break it down for you:

Sony says that, thanks to the phase-detection pixels, the Z5 family can autofocus in as little as 0.03 second, claiming it's the "world's fastest autofocus in a smartphone." All we can say is it's very quick. The actuator helps with this by swiftly moving the lens to focus, and because it's closed-loop, it'll also offer better image stabilization, especially for video. As you'd expect, all three will shoot movies in 4K, although evidently the Z5 Premium is the only one capable of playing footage back natively on the phone itself. Sony says the new sensor is capable of oversampling images (PureView style) for digital zoom "without loss of image quality." Take that claim with an ocean's worth of salt, of course, but the zoomed images definitely seemed good enough for a Facebook or Twitter share.

Click image for original 3MB file. Shot by Sony at f/2.0, 1/30s, ISO 250.

All of this adds up to... well, no one knows yet. What I can say is that Sony's sensors are the envy of the business; Sony's "unedited" sample images look fantastic; and, in my brief time with the Z5s, I took some quite pretty images that I'm sadly unable to share with you. But it's too early to say whether this new camera represents a huge leap forward, or even if it's at the front of the pack.

A fresh start

Although it's not quite stock, Sony has all but removed its Android skin.

On the software side, the Z5 family runs Android 5.1.1, and Sony says "stay tuned" about an Android M update. The good news for virtually everyone but the most die-hard of Sony fans, though? The company's Android skin is no more. Instead, the devices all run a virtually stock Android experience. Sure, there are some differences in iconography, but the general look-and-feel isn't too far from a Nexus device. That's a huge step forward from current Xperias, which feel like they're stuck in the past despite many of them actually being on the latest version of Android.

Google won't officially bake in fingerprint support to its OS until Android M is released this fall. Like other manufacturers, though, Sony already has things up and running. I wasn't able to test out the functionality myself, but the placement seems very natural, and I watched Sony staff unlocking their devices with various fingers and thumbs at a 100 percent success rate.

The big questions

A close-up of the Xperia Premium's etched metal wordmark.

I'm pretty impressed with Sony's new lineup. But there are still three lingering questions that Sony needs to answer. First, there's the small matter of price. So far, we've got this from Sony: "Pricing will reflect the premium quality of the smartphone." Make of that what you will, but Sony isn't exactly known for producing budget devices. In the age of the OnePlus 2 and the Moto X Pure, you can get a lot of smartphone for a few hundred dollars.

Second is battery life and performance. The chip inside all three, the Snapdragon 810, has had some well-reported issues with overheating, and is not known to be very frugal when it comes to battery life. Couple that chip with a 4K display, and it's easy to question Sony's claim of "up to two-day" endurance when it comes to the Premium. The company points to its on-display memory (which effectively switches off the processor when the screen isn't moving), and other battery-saving tech as proof it can hit that target. Many will remain unconvinced until the phone's been properly tested.

Third, and perhaps most importantly for Sony's shot at a global success, is availability. The Z5 and Z5 Compact will be "globally" available in October, with the Z5 Premium following in November. But Sony has really struggled to persuade carriers to push its devices. That's especially true in the US, where sometimes it feels like Sony doesn't exist.

If a 4K display doesn't pique the US carriers' attention, nothing will.

You could argue that this is Sony's fault. Several generations of Xperias have come and gone, all of which looked pretty much the same, and none of which blew the competition out of the water. They've been solid phones, but plenty of companies make solid phones. Why should carriers put their weight behind Sony when Samsung et al. offer the same basic package? With iPhone season fast approaching, there's a real chance Sony could be left by the wayside again. At least with the Z5 Premium, Sony has clearly put everything it can into a single device, short of a new design. If the world's first 4K smartphone doesn't get the attention of AT&T, Verizon, Sprint and T-Mobile, nothing will.

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