(From Sigma lens literature) This large aperture wide-angle lens is equipped with macro focusing capability with a maximum magnification of 1:2.7 and fast ƒ/1.8 maximum aperture. The use of aspherical lenses offers superior peripheral brightness and compensation of aberrations and astigmatism. This is an ideal DG lens for Digital SLR cameras.
This lens is capable of macro photography at minimum focusing down to 18cm (7.1 in.) with a maximum reproduction ratio of 1:2.7. It incorporates the floating focus system in order to minimize distortion, spherical aberration and astigmatism, which provides high performance at all shooting distance down to 18 cm (7.1 in.). A maximum reproduction ratio of 1:2.7 and an angle of view of 84.1 degrees allow capturing of high quality images of not only the subject, but also the surrounding scenery.
This lens has an advanced optical construction in order to obtain adequate peripheral brightness at open aperture. Also, the iris diaphragm has 9 blades to obtain beautiful out of focus images in the foreground and background.
This lens also incorporates a Dual-Focus (DF) mechanism. It is easy to hold the lens, since the focusing ring does not rotate during auto-focus, yet it provides adequate focusing torque of the focusing ring during manual focusing of the lens. This also allows the use of a "Petal-type Hood."
