Dual-camera phones started appearing five years ago, spent years dismissed as a bit of a gimmick, but now phones like the Honor 8 and iPhone 7 Plus prove two cameras really can be better than one. They are not copycats, though. These phones have totally different approaches to the concept. And both are entirely valid. Let’s dig a little deeper.
The Honor 8 has two high-quality 12-megapixel Sony sensors that sit next to each other on the back. First off, you’ll notice that unlike a lot of other phones, including the iPhone 7 Plus, neither sticks out from the 7.5mm thick frame.
As well as looking great, this means you’re much less likely to scratch the glass lens covering. Anything that sticks out of a phone is liable to earn a few scrapes after a while.
Carrying the no-compromise style on with the hardware, the Honor 8’s sensors are both Sony IMX 286 models. Most dual-camera phones use one fancy sensor and a second basic one, but not here. For example, the iPhone 7 Plus’s second camera is a “2x zoom” lens, but it takes in less light and doesn’t have the optical stabilisation of the main one.
Honor bucks the trend as the main role of the second camera is to take in more light than the primary one, because it has a monochrome sensor. To explain why a B&W sensor harvests more light, we’re going to have to get a tiny bit technical.
When light enters a camera, the lens directs it towards the sensor, which is stimulated by light in order to piece together your photos. However, in order to tell greens from blues, light has to be split into different colours.
Just before the light reaches the sensor it passes through a colour filter that organises the light into red, green and blue streams. Here’s where the issue arises: in order to isolate green, red and blue light has to be discarded. Camera sensors waste light even though it’s their currency.
This is where the Honor 8’s monochrome sensor steps in. As it doesn’t need to discern colours, it can use more of the light coming its way to make each pixel of the final image. This leads to better sensitivity, meaning superior low-light photos, and better dynamic range with day-time shots.
According to Honor it is like having a sensor with pixels 1.75 microns in size rather than 1.25 microns. That’s a big, big difference. The phone merges together what each camera sees to make its photos. The standard one judges colour while the monochrome sensor acts like a powerful image quality turbo charger. This technological feat is down to years of research by Honor's R&D teams.
As each camera has its own ISP, the brain that processes image data, this merging process doesn’t slow the Honor 8 down either. These ISPs have a lot to handle too: smart scene recognition, noise reduction, post-processing algorithms, face detection and responsibility for image quality. It’s an important job.
This dual lens team is what lets the Honor 8 take such beautiful pictures. You can also take monochrome shots for an instant extra-arty hit if you like.
There are two other great uses for the dual-camera setup too. The first is focusing.
The Honor 8 tackles focusing in three different ways, to lock-on lightning-fast every time. First, it has contrast detection like most other phones. This is where what the sensor ‘sees’ is analysed, and the phone looks for the AF point at which contrast is highest. More contrast means greater sharpness, so max contrast means you’ve hit a perfect focus.
The dual-camera array can help out here because it lets the Honor 8 map out a 3D view of the scene. As the cameras are set slightly apart, just like our eyes, their views are ever so slightly different. This lets the camera brain tell between foreground and background instantly, without having to rely on the contrast detection method we just looked at. It’s pretty smart.
There’s a third helper too. Just next to the Honor 8’s two cameras sits a laser module. This fires out a laser that bounces off your subject and returns to the camera, and the time it takes to return tells the phone how far away it is. Like the dual-camera benefits, it lets the AF skip to the right focus point, letting contrast detection do the final bits of focus fine-tuning.
With these three tools in its arsenal, the Honor 8 is fast to focus in all conditions, even if there’s barely any light with which to work.
When blurry photos are great
The second extra-special feature the dual camera gets you is a simulated depth of field effect. It’s similar to what you’d see from a big DSLR with a £1000 lens, throwing the background out of focus to make your subject pop like nothing else. It gives the Honor 8’s portraits a pro-quality look.
Apple is working on adding this feature to the iPhone 7 Plus, but as we write this it’s in beta and doesn’t give you the control the Honor 8 has. With this phone you can select the aperture you want to emulate: the wider the aperture, the more blurred the background will appear.
The Honor 8 can go all the way down to f/0.95, which makes everything but your subject a deliciously soft blur. And up to f/16, making every part of the image sharp. You can alter the aperture after shooting too, from the Gallery app. With an iPhone you have to just take what Apple gives you.
The Honor 8 is the sort of camera that’ll make even photography nuts leave their big cameras at home more often, and that’s not to be sniffed at.