Smooth AF ideal for video shooting The combination of optical design for video AF and use of the stepping motor enables smooth and quiet autofocus. The lens is also compatible with the Sony E-mount Fast Hybrid AF, achieving precise AF tracking. By using the face recognition or eye AF functions of cameras, focus will continuously be on the face or the eyes even if the subject moves during the shot. High-precision, rugged brass bayonet mount The brass mount combines high precision with rugged construction. Its rugged surface and enhanced strength contribute to the exceptional durability of the lens. Mount with dust- and splash-proof construction The mount features a unique sealing to make the lens an excellent choice in a wide variety of conditions. Impressively compact construction with image quality rivaling SIGMA's Art line. To achieve such a compact construction, lens design is considered based on the strengths of the camera body function to correct peripheral light amount and distortion. In addition, axial color aberration, which is difficult to eliminate by image processing, is corrected by incorporating an SLD glass element. Overall, a compactness and lightweight construction combined with superb image quality is achieved.