A versatile wide-angle zoom for Nikon DX-format DSLRs, the AT-X 11-20mm f/2.8 PRO DX Lens fromTokina offers a 16.5-30mm equivalent focal length and features a constant f/2.8 maximum aperture for maintained brightness throughout the zoom range. One P-MO hybrid aspherical element and two glass-molded aspherical element work in tandem to minimize distortions and control various aberrations while three SD ultra-low dispersion elements reduce chromatic aberrations for increased clarity. A multi-layer lens coating has also been applied to further enhance overall light transmission and color accuracy by suppressing lens flare and ghosting. Well-suited to working in a wide variety of situations, this ultra-wide zoom covers an array of wide-angle perspectives while maintaining consistent illumination for working in challenging lighting.
 
https://www.bhphotovideo.com/c/product/1084644-REG/tokina_at_x_11_20mm_f_2_8_pro.html