The rear camera is one of the most hotly-contested (and ruthlessly-promoted) features in today’s premium smartphones — a fact driven home by the constant jousting for top spot in DxOMark’s renowned best mobile camera rankings. The competition has become so close that, even when vendors like Apple, Google, Samsung or Sony launch a new phone that takes out first place, that ‘winner’ often has to share the lead position — and ultimately, almost all of them have their short reigns overthrown within a few months, or less.
Over the last couple of years, dual rear cameras have slowly become the norm for flagship smartphones, but this year’s Galaxy S8 and S8 Plus bucked that trend by sticking with the same 12-megapixel, single-sensor camera spec that was used in their 2016 predecessors, with just a few enhancements to boost overall picture quality and performance. That’s made the new Note 8 the first device from Samsung that includes a dual-camera array, which — as always — brings with it a raft of much-touted new photography features.
In a recent visit to Samsung’s headquarters in Seoul, South Korea, we chatted to Dr. Yoon Young Kwon from the company’s Advanced Camera R&D Group about the work that goes into building one of the best smartphone cameras on the market, and why the electronics giant decided to change a winning formula for the Note 8. Addressing the larger picture, Dr. Kwon explained that the company’s ultimate goal with its cameras is fairly straightforward.
“Our main focus is to make sure the users feel satisfied with the photos that they take,” he told us. “Samsung started to research the dual camera because we believed it had the potential to offer features that were difficult or impossible to provide through single lens cameras.”
The not so ‘mega’ pixel
According to Kwon, Samsung began researching dual-sensor and lens cameras between four and five years ago, but the reason it’s only first appeared in the Note 8 is due to timing. The Note 8’s launch has lined up with a time when there’s less demand to increase megapixel counts just for the same of doing so, accompanied by a new interest in optical zoom – a feature that’s prevalent with dual camera arrays. Kwon explained that “the megapixel is just one of the factors that influence the picture quality of cameras. If you have a higher megapixel count, that’s more advantageous for printing and large displays, however this also means that the image’s pixel size goes down, which results in lower resolution and lower colour accuracy.”
“We believe that the smartphone user trend is shifting toward on-device photo consumption, where increasing the individual pixel size is helpful for picture quality. Currently, the majority of consumers take the pictures on the device, view them on the device and then share it on the device,” said Kwon.
Bokeh in full bloom
One of the key features that the dual rear camera brings is an effect called ‘bokeh’ where a photo has a particular object in focus, but anything behind or in front of the subject is blurred into obscurity.
“In order to create the bokeh effect, you need to measure the distance between the camera and the object that you are shooting. Using the dual cameras you get two perspectives and, based on the differences between the two images, you can extract the depth information and create the bokeh effect,” Kwon explained.
Single lens cameras can create this effect using dual-pixel sensors, but Kwon noted that this technique is generally too ‘noisy’ to provide consistent results. “The purpose of the dual pixel camera that we’ve had since the S7 is not to create the bokeh effect, but to accelerate the autofocus,” said Kwon.
“[In dual pixel cameras], behind one lens there are two different image sensor pixels, so you have light coming from the left and light coming from the right. You compare the different intensity of the light coming from the left to that of the right, and based on the difference you can estimate the depth and you can estimate the required focus,” explained Kwon. “In DSLRs, there is the face difference technology, which measures the distance between the camera and the object based on face information.” Further iterating his stance on single lens setups, Kwon stated that ”these techniques only provide partial information of what we need and are more noisy than the dual-camera technology. They do not provide enough information to create the bokeh effect.” He explained that “even in the future, it will be difficult to create the bokeh effect using a single lens dual pixel technology.”
That said, the Pixel 2 smartphone, which launched shortly after the Note 8, has manage to score higher in DxOMark, despite its single lens camera. Google’s taken a left-of-field approach however, relying on machine learning algorithms for detecting subtle patterns in dual-pixel readings, which allows it to get a convincing bokeh effect with a just a single lens. It’s a novel breakthrough that defies the former understanding of the limitations in dual pixel technology.
Through another lens
The Note 8’s two cameras consist of a 12-megapixel, 26mm, f/1.7 dual-pixel wide angle camera with a 1/2.55″ sensor size and 1.4µm pixel size, alongside a 12-megapixel, 52mm, f/2.4, telephoto lens with a 1/3.6″ sensor size and a 1.0µm pixel size. In and of itself, simply having two cameras should be enough to give a photographic advantage, but the particular combination of cameras can dramatically shift the feature set from one dual lens camera array to another.
“We chose the combination of a wide angle lens and a telephoto lens because we believed this would be able to provide a very crisp and clear long distance optical zoom that no other smartphone has been able to provide yet,“ said Dr. Kwon.
For consumers, the new camera array brings new features like 2x optical zoom, Live Focus (with realtime bokeh effect) and Dual Capture modes while reducing background noise and improving the low-light quality of video capture. Both cameras have optical image stabilisation and an enhanced set of image processing features, adding up to a considerable bump in the camera quality on the Note 8, as we noted in our review.
Moreover, despite Google throwing its considerable AI advantage behind the Pixel 2’s camera, the Note 8 still produced very good results — even outdoing the Google in some areas. Check out our video face-off where we compare the two (alongside the iPhone 8 Plus and Huawei Mate 10 Pro) and see for yourself.