The Oppo R11 features a dual-camera setup. One camera uses the Sony IMX398 1/2.8" Exmor RS Stacked sensor with 1.12-micron pixel size, the same camera image sensor used in the Oppo R9s smartphone for the rear camera and an upgrade version of the IMX298. I've already seen images taken with this camera and it produce really sharp and detailed images in daylight and has quite good low-light performance as well. The IMX398 is a 16MP sensor boasting a f/1.7 aperture lens. This is a very fast lens that helps push up its low-light capabilities.
The second camera is a 20MP Sony IMX350. The same sensor found in the Axon 7s. It has a 1/2.8" sensor with 1.0-micron pixel size and a 6P f/2.6 aperture lens. When shooting with the 2x magnification, the camera uses this camera. The main problem with this camera is that it has a relatively slow lens compared to the f/1.8 on the 1x zoom lens. This means that it's less suitable for low-light photography, which is something to keep in mind when you take shots during nighttime or in a dark indoor place.
The two cameras have different focal length, one with a wider angle and a second, the IMX350 20MP, with a longer telephoto lens with twice the focal length of the first one, giving you a 2x optical magnification. The Oppo R11 can seamlessly switch between the two. This is kind of the same setup used in the LG G6,but the G6 features an ultra-wide angle lens.
The advantage of a telephoto lens is that it's more suited for portrait shots and when you want to capture an image of a subject which is further away from the camera. The Oppo R11 can also produce images with a very shallow depth of field Bokeh effect, which we all learn to love in many other recently released phones.
Here is an OPPO R11 Plus hands on video shot by mobilegeeks.de. It gives you an example of how the two camera defer in terms of zoom range.
As you can see, there is one camera that captures a wide angle shot and a second that gets much closer to the subject with 2x magnification compared to the first lens.
Just for comparison, the Xiaomi Mi6 also features a rear dual camera setup that offers 2x lossless optical zoom. However, in the Mi 6, both cameras have a 12MP Bayer image sensors, one with 27mm equivalent focal length and a second with a 52mm equivalent focal length. I think that having two sensors with identical resolution might help producing more accurate bokeh effect, which what the Mi 6 does as well, but I am not sure about that. I'll have to see some OPPO R11 sample images to see how well the digitally generated bokeh effect is in that phone. The R11 still uses the data from both cameras to produce a depth of field effect for portrait shots. Judging by the results seen in the video above, it looks pretty good.
2x optical zoom is nothing new and although it's a great feature to have in a phone, I'm looking forward to the first company who will bring us greater magnification. By the way, Oppo already showed off a 5x optical zoom camera prototype in Mobile World Congress which it intends to use in its future devices (check this video out). As for no, OPPO is just following the popular trends with really nothing revolutionary, but this will change when and if that 5x camera comes out. Oppo can really make a name for itself in the camera category (if another company doesn't release it before Oppo, this can certainly happen).
In the Oppo R11 and R11 Plus camera UI you have a circular icon showing 1x on the bottom (portrait orientation) / right (landscape orientation). 1x means that the camera is currently shooting in normal mode, with the wider field of view. You can tap on that icon and it will change to 2x, which means 2x optical zoom. In that mode you are shooting with the second telephoto camera. The transition between the two is very smooth, although you don't get to have that smooth transition as you get with a 2x optical zoom lens. This is not a zoom lens, it is just two separate cameras and you just switch between the two.
Here is another video by finder.com.au that posted an Oppo R11 hands-on review. You can jump to minute 2:08 to check out how the R11 2x zoom looks in the camera app itself.
All in all, the OPPO R11 Plus dual-lens camera is one of the key features of this phone. It brings better versatility and creative options to the hands of every user who buys this new smartphone. The fast aperture lens on the wide-angle camera ensures good image quality even in low-light compared to some other camera setups from other companies that are less impressive in that aspect. It's great to see a dual camera coming to the mid-range segment and I'm sure more and more companies will implement this type of camera system in their mid-range phone's lineup. If you love this feature on premium phones, now you can have it in a less expensive smartphone.
If you prefer an ultra-wide angle lens instead of a second telephoto lens, you might want to check out the LG G6 dual-camera setup. It's certainly better if you enjoy taking pictures of landscapes, group or indoor shots.