Xiaomi announced the new Mi 10 Youth Edition yesterday and the phone managed to attract many ayes thanks to the complex and potent camera setup. Even though it is a mid-range smartphone, the device will be capable of taking great photos and even have a 5x optical zoom and 50x hybrid zoom capabilities. In a detailed post on Weibo, Xiaomi explains how the periscope camera present on the Mi 10 Youth Edition works.
The Mi 10 Youth Edition has a four-camera camera module on the back. The main camera has a 48MP sensor, an 8-megapixel telephoto camera, another 8-megapixel ultra-wide lens, and a 2MP macro lens, covering a 15-122mm superlens. The 8MP telephoto lens camera is the interesting one since it has a periscope configuration capable of 5x lossless zoom and 50x hybrid zoom. The periscope lens structure is relatively complex and is usually only used for flagship models, but Xiaomi managed to include it in a mid-range smartphone.
With normal cameras and lenses, only 3x zoom was capable on smartphones, but with this modules similar to the ones present on the Mi 10 Youth Edition, the company managed to achieve 5x zoom, with more advanced version being able to surpass even this. Telephoto lenses are actually not uncommon in mobile phones. Most three-camera and four-camera mobile phones will be equipped with a telephoto lens to achieve lossless telephoto shooting. But to achieve a longer focal length, the lens length must also be longer.
This is a schematic diagram of the focal length and the shooting distance (the actual lens group is much more complicated than the above picture). To achieve higher magnification zoom, the distance between the lens and CMOS is also longer, which means that the camera module will be thicker.
How is the periscope lens implemented? Right-angle prisms change the direction of the optical path so that the mirror group can be placed horizontally. The video above further explains the lens and prism placement as well as the position of the image sensor. As can be seen in the image, there is a prism that redirects light to the 5-lens setup that better focus and adjust the image quality that is then captured by the sensor.
After refraction, the light changes its path, passes through the 5P lens, and finally enters the CMOS device for imaging. The lense setup also has optical image stabilization, something that is also usually found on high-end devices only. With a telephoto lens, any jitter will be magnified infinitely, making it very easy to blur. Therefore, optical image stabilization is more needed to ensure image quality. Mi 10 Youth Edition’s periscope combination lens uses a split OIS control system.
The reason why it is called split OIS anti-shake is because the vertical OIS of the right-angle prism part and the lateral OIS of the 5 lens group part are independent structures (as shown above). The XY axes are independent of each other, without crosstalk, and the physical structure guarantees the stability of the picture without the slight deflection of the image. Because the periscope lens group has a longer optical path and a complicated structure, it must also ensure that other devices in the optical path do not affect the light. The Xiaomi Mi 10 Youth Edition uses an extinction motor to change the reflected light from the inner wall of the motor from an orderly reflection to a diffuse reflection, eliminating a large amount of extra specular reflection light and ensuring clean and transparent photos.
Since the image sensor and lens are perpendicular on the phone, there was a high risk of increasing the thickness of the device. Xiaomi used a so-called D-Cut technology that reduces the thickness of conventional periscope lenses by 7.6%. Compared with mainstream products on the market, Xiaomi Mi 10 Youth Edition may be the thinnest periscope zoom phone.