Sony Xperia 5 III uses a periscope camera with two Zoom settings
The Package channel continued building its periscope camera report database with a look inside the Sony Xperia 5 III smartphone. Notably, this is the first periscope camera TechInsights has examined that has a variable zoom; the magnification of the camera has two zoom settings.
The focal length of the camera can be either 70 mm (x3 optical zoom) or 105 mm (x4.4 optical zoom). The changing focal length is achieved by shifting lenses within the lens barrel between two different positions. This is purportedly faster than switching between two different telephoto cameras, the approach used in the Samsung Galaxy S21. The zoom is set using a virtual button on the camera app.
The back facing (main) camera on the handset is a triple configuration combining a 12 MP wide camera (focal length 24 mm) with the periscope camera and a 12 MP ultrawide camera ( focal length 16 mm). Zeiss T* coatings are used on the lenses to reduce ghosting and internal reflections.
The basic idea of a zoom lens is well known. The focal length of the lens (or the viewing angle of light that strikes the sensor) is changed by physically moving some of the lenses in the optical barrel. Consulting Figure 1, a sliding element in the barrel changes the effective zoom. Consider the orange light rays that enter the lens at the same angle in both images. When the middle element is close to the sensor (left hand side) , the orange rays strike the sensor plane further from the center of the array (i.e. the optical zoom is greater or the focal length is greater). Moving the middle element further from the sensor (right hand side) the orange rays now converge closer to the center of the array (i.e. the optical zoom or focal length is reduced).
The periscope camera in the Sony Xperia 5 III implements zoom using a similar lens arrangement, shown in Figure 2, a top X-ray of the module. Light enters from the top, striking the periscope mirror (a right angled prism) that folds the light down the optical barrel .
The barrel is divided into three separate lens assemblies; barrel 1 has 3 lenses that are fixed in place, barrel 2 has 2 lenses that can be in one of two positions in order to set the zoom and barrel 3 has two lenses and can be continuously adjusted for a total of seven plastic lenses in the camera. Barrel 2 is mounted on a plastic slider that shifts between the two positions using the indicated actuator. Barrel 3 uses a separate actuator mounted on the opposite side of the module and performs fine adjustment to focus the imager. A third voice coil is placed under the periscope prism and adjusts the tilt of the prism to perform Optical Image Stabilization.
Manufacturers will continue to explore variable zoom cameras as a way to improve high magnification performance. The mechanical constraints likely restrict theses devices to periscope cameras. Oppo announced in August 2021 a periscope camera with a continuous optical zoom with a focal length range of 85-300 mm, the release date has not been announced.
The main competing alternative is the use of multiple telephoto cameras in a vertical configuration, with each camera having a different magnification. A novel alternative is the use of deformable lenses; the Xiaomi M MIX Fold uses a “Liquid lens” to this effect.
TechInsights provides more details on the Sony Xperia 5 III periscope camera package in this report.