*20mm focal length, F2.8 aperture *8 groups of 10 elements optical construction, including 2 ED lenses, 1 lenses with high refractive index and 2 aspherical lenses *HD Nano multilayer coating with water-resistant and antifouling coating *Electronic aperture,internal focus,constant lens length *Noiseless STM focus motor *Precision hardened aluminum alloy bayonet *Convenient and lightweight