Ống kính máy ảnh Lens Sigma Wide Angle 28mm F1.8 Macro

       This 28mm lens has a fast f/1.8 maximum aperture, with macro-focusing capability. It features minimum focusing, down to 7.9" with a reproduction ratio of 1:2.9). The 9-bladed aperture diaphragm obtains beautiful out of focus images. It incorporates the floating focus system and the use of two aspherical lens elements to minimize distortion, spherical aberration and astigmatism. The lens incorporates minimum vignetting optical construction in order to obtain adequate peripheral brightness with open aperture. Internal focus system of the lens eliminates front lens rotation, thus allowing the use of a perfect hood and easy use of polarizing filters. The lens also incorporates a dual-focus mechanism. It is easy to hold the lens, since focusing ring does not rotate during autofocus, yet provides adequate torque of the focusing ring during manual focusing. The lens materials used in this new lens are lead and arsenic free ecological glass.