How do photo lens stretch and retract?

The extension and retraction of photo lens are mainly achieved through mechanical structures (such as motor drive or manual rotation) to adjust the distance between the lens and the photosensitive element, in order to achieve zoom or focusing functions. The specific operation method varies depending on the camera brand and model.
Working principle of telescopic lens
The essence of camera lens extension is to adjust the imaging effect by changing the physical distance between the lens group and the photosensitive element. This process may involve the following technologies:
Mechanical Drive: High end cameras or mobile phones (such as Huawei P70 Pro+) use precision stepper motors to control lens extension and retraction, which are triggered by circuit signals. ‌‌‌‌
Manual adjustment: Traditional photo lens are usually extended or retracted by rotating the zoom ring on the lens barrel or pressing a dedicated button. For example, Canon cameras can be operated by rotating the lens ring clockwise or pressing the "retract" button. ‌‌
Common operating methods
There are significant differences in the scalability control methods for different devices
Automatic mode: Some smart devices (such as Huawei phones) will automatically extend the lens to optimize image quality when detecting ambient light or zoom requirements. ‌‌
Manually triggered:
Camera: Controlled by physical buttons or rotating rings, some models support automatic retraction in standby mode. ‌‌
Professional mode: allows users to manually adjust parameters and control lens extension and retraction, suitable for fine shooting needs. ‌‌
Technical Implementation and Design Considerations
The design of telescopic lenses needs to balance volume and imaging quality:
Mechanical structure: High precision guide rails and motors are used to ensure telescopic stability and avoid shaking affecting imaging. ‌‌‌‌
Optical performance: During the stretching process, it is necessary to maintain the alignment of the optical axis of the lens group to prevent aberration or loss of image quality. ‌‌