Rokinon 10mm F2.8 ED AS NCS CS Ultra Wide Angle Lens for Pentax K and Samsung K Mount Digital SLR Cameras (10M-P) Nano Crystal Coating System (NCS) for increased light transmission and reduced internal reflections Fast F2.8 maximum aperture + close-focusing to 9.5 inches = maximum versatility in all shooting conditions Optimized for excellent optical quality and true ultra-wide 110 degree edge to edge coverage with APS-C sensor digital cameras Utilizes 3 high precision (2 Aspherical + 1 ED) lens elements for superior image quality Inner focusing system (IF)  length doesn't change and front element does not rotate  keeps integrated petal-type lens hood properly oriented