The Sigma EX 12 mm - 24 mm is a wide-angle lens which has the varying angle of view in the range of 84.1 degrees to 122 degrees. The focal lengths can be adjusted in the range of 12-24 mm whereas the minimum focusing distance of the f/4.5-5.6 Sigma lens has the value of 11 inches at all focal lengths. The Sigma EX 12 mm - 24 mm comes with an inner focusing system, which means that the length of the lens stays the same at every focal length. Moreover, a hypersonic motor is also included in the lens guaranteeing high quality photos fast. The optical construction of the wide-angle lens consists of 16 elements, which have been arranged into 12 different groups and include three aspherical elements as well as 4 special low dispersion elements. These optical features correct the distortion and aberration and ensure higher performance levels. Furthermore, the Sigma lens comes equipped with six diagonal aperture blades. As far as the dimensions of the Sigma EX 12 mm - 24 mm are concerned, they are 3.9 inches by 3.4 inches by 3.4 inches while the filter size is 82 mm and the lens weighs 1.4 Ibs. The lens can be used with digital Sony and Minolta SLR cameras.