A fast maximum aperture of F1.8 with macro focusing capability down to 18cm/7.1 inches (reproduction ratio 1:2.7). The iris diaphragm has 9 diaphragm blades to obtain beautiful out of focus image. It incorporates Sigmas floating focus system and uses two aspherical lens elements for minimizing distortion and spherical aberration and astigmatism. Internal focus system eliminates front lens rotation, thus allowing the use of a Perfect Hood and the easy use of polarizing filters. The lens incorporates non-vignetting optical construction, in order to obtain adequate peripheral brightness even at open aperture. This is desirable for digital cameras. The lens also incorporates dual-focus mechanism. It is easy to hold the lens, since focusing ring does not rotate during auto-focus, and yet it provides adequate focusing torque of the focusing ring during manual focusing of the lens. The lens materials used in this new lens are lead and arsenic free ecological glass.
All the features of this lens help to give excellent distortion free photos from corner to corner and will provide you with faithful colour and contrast performance.