The tokina 17 35mm f4 at x pro fx lens is designed is a compact wide angle zoom with a constant bright f4 aperture which makes shooting in low light situations possible designed for full frame cameras the tokina 17 35mm f4 at x pro fx lens includes two super low dispersion glass elements and 1 aspheric glass to ensure excellent contrast and sharpness is achieved with minimum chromatic aberration by simply snapping the focus ring forward you can switch from af and mf allowing you to capture t