Sigma HF

Sigma HF ... of front lens elements. Thus the front of the lens does not rotate it allowing the use of a "perfect hood" and the easy use of polarizing filters. Minimum focusing distance from the film plane to subject at all focal lengths is 15.7inch (40cm). It incorporates aspherical lens to minimize distortion, spherical aberration and astigmatism, resulting in high image contrast and resolution. The lens also features a depth of field scale that serves for determining the subject's depth of field at a specific focal length and distance. The lens materials used in this lens are lead and arsenic free ecological glass.