Focal Length: Determines the lens's field of view and magnification, usually indicated in millimeters (mm). Short focal lengths are suitable for wide-angle shooting, while long focal lengths are suitable for long-distance shooting. Aperture: Indicates the lens's maximum aperture size, affecting the amount of light entering and the depth of field. The smaller the aperture value (e.g., f/1.8), the more light enters, and the background blur effect is more pronounced. Lens Type: Common types include prime lenses (fixed focal length) and zoom lenses (adjustable focal length). Prime lenses are usually brighter and have higher imaging quality, while zoom lenses offer greater flexibility. Optical Features: Such as aspherical elements and low-dispersion elements, can improve image quality and reduce distortion and chromatic aberration. Compatibility: Lenses from different brands may only be compatible with specific camera models. Before purchasing, it is necessary to confirm the compatibility of the lens with the camera.