The Blackmagic URSA Mini B4 Mount is an accessory for URSA Mini PL models that lets you swap the built in PL lens mount on your URSA Mini with a B4 lens mount. Featuring precision glass optics, the B4 mount is specifically designed to match URSA Mini’s sensor with high definition B4 lenses. The mount also has spherical aberration correction so lenses can be used wide open with no blooming effect. B4 lenses can be fully electronically controlled from the URSA Mini PL lens control connection.