• 17 pieces in 15 groups adopt 2 SLD glass and 3 aspherical lenses to compensate for aberrations. It achieves high image reproductions from 1.4 open F to 1.4 degrees, and the image is clear and high uniformity without flowing from the center of the screen to the peripheral. In particular, the Sigma's largest large double-sided aspherical lens thoroughly reduces sagittal coma flare and image curvature to create a small star at every corner of the screen while maximizing the angle of view with an ultra-wide angle of 0.8 inch (20 mm) • With a focus mode switch, AFL button to assign any function from the camera, MFL switch to prevent accidental operation, aperture ring lock switch, anti-drop locking mechanism and non-slip rubber parts, the attached flower hood supports you to perform the shooting scene • The lens heater retainer is used to properly attach the lens heater to prevent condensation from forming inside the lens • Sony E-Mount