With Apple announcing the iPhone 7 Plus with two cameras on the back, it's worth looking at where this has come from and romp through the history of dual lens smartphones.
Dual lens cameras on smartphones aren't new, with a number of models offering a range of unique features using this camera setup.
Apple might be bringing it to the masses in 2016, but follow us as we walk you through smartphones dual lens camera systems of the past and present.
LG Optimus 3D and HTC Evo 3D: Another dimension
In 2011, 3D was a thing. The world's TV manufacturers were lining up 3D TV sets, there were 3D films being produced and we were being told that 3D was the next big thing, again.
For smartphones, it was the opportunity for innovation. The LG Optimus 3D was announced in February 2011 and the HTC Evo 3D launched on Sprint in March 2011.
Both these smartphones (and there were some others) used dual lenses to allow them to take 3D video and 3D photos. They use the same technique used by regular 3D cameras, using those dual lenses to create a sense of depth in images. This was boosted with a 3D display to view those images, without the glasses.
But 3D was just a passing phase, and although we could capture 3D, ultimately, that was only the start of the story for dual lens cameras.
- LG Optimus 3D vs HTC Evo 3D: Which has the better 3D camera?
- LG Optimus 3D review: Seeing double
- HTC Evo 3D review: Three's a crowd
HTC One M8: Making sense
It was the HTC One M8 that really introduced dual lens cameras to the world and saw HTC trying to do something different. The HTC One M8 was launched in April 2014.
With a 4-megapixel UltraPixel main image sensor and a secondary 2-megapixel sensor capturing extra data, the dual lens camera was used, like 3D, to create a sense of depth in photos. The idea was that the second lens could capture this depth information to create a depth map and feed it into the final image.
That meant you could create bokeh/background blur effects, you could refocus the image with a tap and you could easily manipulate photos, keeping the subject sharp and changing the backgrounds.
The One M8 was clever, but the camera wasn't that impressive. The effects were rather gimmicky and the benefits of having a dual camera didn't really make an impact - even if the full metal body did.
LG G5: Going wide
Suddenly we arrive in 2016 and LG announces the LG G5 in February. There are two things that are interesting about it. Firstly, it attempts to integrate modular accessories. Secondly, LG has equipped it with dual cameras.
In the case of this LG smartphone, there's a main 16-megapixel sensor and a second 8-megapixel sensor.
Rather than combining information to create effects, LG's dual camera approach is straight shooting. The 16-megapixel camera offers regular photos, but the second lens is wide-angle.
With 135-degree lens on the rear for that 8MP camera, the LG G5 can shoot wide-angle photos to great effect. You simply switch from one camera to the other by tapping the button in the app and you can get more in. Perfect for tight spots or landscapes, with that slight fish-eye effect that's on trend.
It's a lovely addition that actually adds something to the feature set. While panorama is common, there's no shortage of after-market wide-angle lenses you can clip on, but the G5's pairing is more useful as it's so simple to use.
Huawei P9: Leica's monochrome mark
With LG making its mark, Huawei launched the P9, in partnership with Leica, in April 2016. With two cameras sitting on the back, Huawei's big selling point wasn't about depth sensing or wide-angle, it was about monochrome.
Leveraging Leica's classic monochrome cameras, the Huawei P9 presented two cameras on the rear, claiming one lens captured RGB colour and the second lens captured monochrome detail. Both cameras are 12-megapixels.
This results in some great black and white photos, but working together, the P9 attempts to combine information from both sensors to make all your photos better. The results are very good, it's a very capable partnership.
There's also a P9 Plus with the same offering, but slightly larger.
- Huawei P9 Leica camera explored: Double the camera, double the fun?
- Huawei P9 review: The flagship and the folly
Honor 8: Slightly less Leica, but very much the same
With the Huawei P9 launched, it was only a matter of time before sub-brand Honor produced an equivalent model. Called the Honor 8, again, there was a dual camera on the back.
With the Leica tie-in being for the Huawei phone, the Honor 8 doesn't make much of the monochrome side of things, but again offers twin 12-megapixel cameras, one with an RGB sensor, the other with a monochrome sensor.
The message is the same: data is combined to result in sharper images, with better grip on colour and monochrome detail. Again, the result is a camera that's very capable, especially on a phone that's purportedly mid-range.
Apple iPhone 7 Plus: A play to zoom, with bokeh to come
The Apple iPhone 7 Plus features two cameras on the rear. Both are 12-megapixels, both offer optical image stabilisation, but they offer a different focal length. The first camera offers 23mm zoom, which is sort of wide - not super wide like LG, but wider than the old iPhone camera.
The second camera is zoomed at 56mm. This means that everything appears closer through this lens. It's like LG's pairing, but reversed. The idea, according to Apple, is to let you zoom without losing so much quality. To get closer to the subject you can switch to the 56mm camera and any digital zooming you then do is starting from a closer position, so the loss in quality will be slightly lessened compared to a regular smartphone camera.
Apple is also looking to play HTC's game by offering a portrait bokeh effect. This will aim to get you that blurred background effect that is created by shallow depth of field on DLSR cameras. Using information from both sensors it will create a depth map, keeping the subject sharp and blurring the background.
This latter feature will arrive as a software update later in 2016.