Sony has a slightly different release cycle to the rest of its competition, normally announcing a new handset every 6 months rather than one a year. The Xperia Z1 arrived in 2013 and since then we have seen the Z2, Z3 and the Z3+.

The Xperia Z3+, known as the Xperia Z4 in Japan, launched just a couple of months ago but that hasn't stopped rumours and speculation flying around for the Xperia Z5. The Z3+ felt rather incremental rather than the huge step forward, as we discovered in our review.

Step forward, then, the Sony Xperia Z5. With IFA 2015 fast approaching, the rumours have been hotting up. We've been filtering through the gossip to bring you a better picture of what to expect come Xperia Z5 launch day.

Sony has tweeted a photo of smartphone with reference to a reveal on 2 September - right when IFA 2015 kicks-off, so it looks pretty certain that we'll be seeing one or more new Xperia handsets at IFA 2015. This fits with murmurings that the Xperia Z5 would have a September release.

There are also rumours of more models, including a Z5 Compact and a Z5+. Whether all these models will launch, or if all the rumours are pointing to the same devices, isn't clear at the moment. Recently we've seen more leaks suggesting three sizes: Sony Xperia Z5 Compact, Sony Xperia Z5 and for the first time, we've seen the Sony Xperia Z5+ referred to as Z5 Premium.

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The Sony Xperia Z range has stuck to the same OmniBalance design since it began. There has been some refinement over the handsets, but nothing too dramatic. From the Z1 to the Z3+, you get a flat rectangular slab that features an aluminium frame and a tempered glass rear.

The Z3 rounded off the edges slightly while the Z3+ dieted for a slimmer waistline. The latest device also did away with the flap covering the Micro-USB charging port.

Leaked images claiming to be a display model in a case show that the Z5 may have a squarer profile than previous devices. That matches a leak showing the phones compared to an iPhone, revealing two sizes and the fingerprint scanner.

There have been several reports of a fingerprint scanner on the side, pictured in leaked Z5 photos and schematics, seeing the traditional round aluminium power button giving way to a flat power button incorporating the fingerprint scanner.

An educated guess would presume the IP68 ratings will remain for the new device(s), as this is one of the unique features that Sony sells itself on.

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Interestingly, the chatter around the Xperia Z5 display has focused on its size, rather than its resolution. Apparently we will see a bump up to a 5.5-inch display on the new smartphone, but the resolution is said to be sticking at Full HD, which would mean a pixel density of 401ppi.

Sony has always stood its ground when it comes to resolution, claiming that users don't want to compromise battery life for the extra pixels and it probably has a fair argument there. That said, to up the screen size and not the resolution seems like a strange move, especially given QHD displays are being seen more and more on competing handsets.

Sony also changed direction with the Z4 Tablet, making the move to 2K, so the Z5 may also follow suit.

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Sony has its fingers in many pies, cameras and audio being two of them. Rumour has it that the Xperia Z5 will also offer the 20.7-megapixel rear camera but if past patterns are anything to go by, you can expect to see some changes, whether it be the lens itself or the camera apps and features.

Sony teased a photo on Twitter of what's presumably the Z5 in a blurred photo saying, "Get ready for a smartphone with greater focus. All will become clear on 02.09.2015". Faster laser-autofocus perhaps? Or maybe after-shot focus selection. Either way we'll find out on that date at IFA.

An 8-megapixel front camera has also been speculated. Sony added some of the features available for the rear camera to the front with the Xperia Z3+, so we'd expect these to be present on the new flagship too.

One thing that is pictured is a dedicated camera button. 

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The Sony Xperia Z3+ arrived with the Qualcomm Snapdragon 810 processor, 3GB of RAM and 32GB of storage. These are the same specs rumoured for the Xperia Z5, but again, we would take this with a pinch of salt as this pretty much suggests the only thing set to change on the new flagship is the display size and design.

Sony has been known to put the latest from Qualcomm in its new handsets in the past, and considering the Snapdragon 820 chipset was announced with an end of 2015 release date, it's not impossible. This was the processor reported in previous rumours in the early part of the year.

We wouldn't be surprised if 32GB storage was accurate, along with microSD support for storage expansion, unless Sony changes the design dramatically. It would be great to see 4GB of RAM to match the OnePlus 2, but at the moment, most recent rumours say 3GB.

A reversible USB Type-C connector and a 4500mAh battery have also been rumoured but while the former is plausible, 4500mAh sounds a little like wishful thinking.

There haven't been any rumours relating to the software we might find on the Sony Xperia Z5 as yet, but we suspect the latest version of Android Lollipop will be on board, along with Sony's usual overlay.

Expect the PS4 Remote Play feature, along with the Sony Entertainment apps at the very least.

Keep checking back as we will update this feature as soon as we learn anymore about the Xperia Z5.