This ultra wide angle lens has the shortest focal length in the l series element 2 is an aspherical lens to correct distortion other aberrations such as astigmatism are also corrected resulting in idea image quality the lens has a fixed petal type hood and a gelatin filter holder at the rear lens construction 14 elements in 10 groups diagonal angle of view 114 degrees focus adjustment rear focusing system with usm closest focusing distance 025m 08ft filter size