Sigma 15-30mm F3.5-4.5 EX Aspherical DG DF AutoFocus Super Wide Angle Zoom Lens         

This rectilinear 15-30mm f3.5-4.5 EX Aspherical DG DF lens provides focal lengths from 15mm ultra-wide angle to 30mm wide-angle and is the first of its kind in the world. This lens has minimum focusing distance of 11.8 inches (30 cm) at all focal lengths with 110.5 degrees (wide) to 71.6 degrees (tele) of angle of view. (Maximum magnification is 1:6.)

It incorporates hybrid aspherical lens in the front lens group to minimize distortion and astigmatism, and molded glass aspherical lens in the rear lens group to minimize spherical aberration.

This lens equipped with dual focus mechanism and also inner focusing system. It is easy to hold the lens, since the focusing ring does not rotate during auto focusing, and yet it provides adequate torque of the focusing ring during manual focusing the lens.

This lens is desirable and for digital SLR cameras also. Its effective zoom range will be 22.5mm-45mm wide angle zoom lens on most SLR digital cameras. Sigma 15-30mm f3.5-4.5 EX Aspherical DG DF has a mechanical design which has six groups zoom system. This mechanical design will minimize astigmatism for all focal lengths.

This lens is equipped with a non-removable type lens hood (Petal-shaped) to prevent extraneous light harmful for image quality. This lens uses rear gelatin (insert type) filters. The iris diaphragm has 8 blades to obtain beautiful out focus of image in the foreground and background.

Specifications
Construction 13 groups /17 elements
Angle of view 110.5°-71.6°
F stop range F22-32 / F3.5-4.5
Closest Focusing Distance 12 in. (30cm)
Maximum Magnification 1:6
Filter Size Rear (gelatin filter insert type)
Dimensions (Length x Diameter) 3.42 in. (dia) x 5.12 in. (length) 87mm (dia) x 130mm (length)
Weight 21.8 oz. (615g)
For Canon
For Nikon