1、Equipped with a round filter holder to support the installation of 72mm/2.8in diameter filters. 2、The front of the lens is equipped with removable metal hood, one corner is hollowed out to prevent obstructing the eyepiece viewing angle. 3、Metal lens barrel, aviation‑grade aluminum anodizing process, fine sandblasted surface, focus ring is equipped with metal focus handle. 4、F1.5 large aperture with 21mm wide‑angle focal length, enables the background to show information in humanistic subjects, and obtain a three‑dimensional sense of space. 5、13 elements in 11 groups optical structure design, including 5 high‑folding lenses and 1 APSH lens structure, compressed in 70mm in length. 6、In the design, the idea of using a fully opened aperture to reduce the contrast and closing one gear to obtain the best center sharpness.