Smartphone manufacturers want to add DSLR type of features in mobile phone cameras. DSLR cameras have lenses with variable focal length and zoom lenses, while smartphone cameras are limited to small and fixed lenses. Mobile devices often depend on digital zoom to close in on details in an image. However, digital zoom have limited resolution and set field of view for near and far details, meaning that a pixel can only capture fewer detail at a distance. So, images mostly appear pixelated as user zoom in, and it’s the same as simply magnifying the image in a gallery app post shutter. Variable lenses in DSLR cameras provide adjustable focal length and longer focal length narrows the camera’s field of view, therefore same limited resolution image sensor captures its detail over a smaller area, so each pixel represents a finer point in space. Optical zoom doesn’t suffer from the same pixelation problems as digital zoom.
Dual camera phones have two cameras including a primary camera and a second primary camera. Primary camera does the same work with basic modification as it does in typical smartphone while the second primary camera normally has two features. First feature is to enhance clarity of the image with the help of monochrome feature and the second is for zooming of image. In some mobile devices, dual lens camera is used to take the pictures and the other one is to capture the depth of field. Advantages of dual cameras include greater depth of field in pictures, faster focus, and refocus ability and better picture clarity.
The basic purpose of using two sensors to improve quality of image, but each phone manufacturer has a slightly different approach in using this technology.
Apple uses second camera by permanently zooming in telephoto lens, with the device switching between them whenever necessary and Apple’s software makes the transitions as easy as possible.
Huawei’s smartphones, including the Huawei P10, is the most technically complicated and involves two separate sensors, but the difference here is that one of them shoots exclusively in monochrome. This camera setup is more sensitive to light, and can therefore take better photos in low-light conditions.
Qualcomm also have introduced Clear Sight technology which requires a Snapdragon 820 or 821 processor in the device. Qualcomm designed it to make dual cameras easier to integrate without requiring specialized development and it utilizes second camera to enhance image quality by pairing a color sensor with a monochromatic one that's able to capture greater detail. The output from the pair of sensors is combined into a theoretically sharper photo.
Main benefits of this technology include superior quality zoom at long distances and superior post processing effects, including advanced HDR. The dual camera system proves more useful in the budget range mobiles where manufacturers can’t afford to put in the best available costly sensors. Dual camera performance is more of a function of software than hardware and this technology will improve with time in upcoming devices.