An improved version of Leica's ultrawide lens for the R-mount series of SLR cameras, the new 15mm f/2.8 exhibits several improvements over its predecessor such as smaller dimensions, internal focus, a great depth of field scale & just 2% barrel distortion. The lens is composed of one aspherical & four low-dispersion glass elements. The light loss at larger apertures is incredibly low, at just 1.3 stops in the corners.