APS-C Format - F/1.8 to f/16, 52.5mm (Full-Frame Equivalent for APS-C), Eye Detection AF Compatible, Autofocus with Digital Stepping Motor, 1 ED Element, 2 High Index Elements, Aircraft-Grade Aluminum Construction, Multicoating, 52mm Front Filter Size, 9 Aperture Blades, USB-C Interface for Firmware Upgrades. A versatile normal-length prime lens the AF 35mm f/1.8 Lens from Yongnuo is a 52.5mm-equivalent lens designed for APS-C-format FUJIFILM X-mount mirrorless cameras. It is well suited to street photography and casual portraiture. The lens's bright f/1.8 design suits working in low-light conditions and also enables increased control over depth of field for isolating subject matter. The optical design incorporates a low dispersion elements and one high reflective index element which helps to reduce chromatic aberrations and color fringing. The lens elements feature multicoating to suppress flare and ghosting for improved contrast in strong lighting conditions. The lens has a DSM autofocus system which promotes fast and quiet focusing performance to suit both photo and video applications.The lens barrel is made with precision machined aviation-grade aluminum alloy for durability and long life. The barrel has a USB-C port for installing firmware upgrades for any future camera designs.