Sigma 17-50mm F2.8 EX DC OS HSM is an Auto Focus (AF) Standard Zoom
lens with APS-C / DX max sensor coverage and it is designed to be used with Pentax KAF3 mount cameras.
Sigma 17-50mm F2.8 EX DC OS HSM is compatible with cameras that have Pentax KAF3 lens mount.Some of the latest released cameras with Pentax KAF3 lens mount are
Max sensor coverage of Sigma 17-50mm F2.8 EX DC OS HSM is APS-C / DX.
Sigma 17-50mm F2.8 EX DC OS HSM has a focal range of 17-50mm and 2.9X zoom ratio.
Optical Image Stabilization
Sigma 17-50mm F2.8 EX DC OS HSM features an optical image stabilization system which helps to reduce the blur that occurs due to shaking during hand-held shooting.
Sigma 17-50mm F2.8 EX DC OS HSM features Rotary (extending) zoom method where the length of the lens changes as you zoom in or out. This makes it possible to design the lens with a smaller minimum length ( generally when it is zoomed out) compared to internal zoom lenses. The disadvantages of this design are being harder to seal against dust and moisture, weight balance shifting while zooming and zoom creep in certain lenses.
Sigma 17-50mm F2.8 EX DC OS HSM is a fixed aperture lens with a constant max aperture of f2.8 from 17mm all the way to the 50mm .
Sigma 17-50mm F2.8 EX DC OS HSM's optical formula consists of 17 elements in 13 groups.