Sigma 18-50mm F2.8-4.5 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 18-50mm F2.8-4.5 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 18-50mm F2.8-4.5 DC OS HSM is APS-C / DX.
Sigma 18-50mm F2.8-4.5 DC OS HSM has a focal range of 18-50mm and 2.8X zoom ratio.
Optical Image Stabilization
Sigma 18-50mm F2.8-4.5 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 18-50mm F2.8-4.5 DC OS HSM features Rotary (internal) zoom method where the length of the lens doesn't change while you are zooming in or out. Even though this design has a size disadvantage in general compare to extending designs, it has the benefits of better sealing against dust and moisture, no zoom creep and no weight balance shift while zooming.
Sigma 18-50mm F2.8-4.5 DC OS HSM is a variable aperture lens with a max aperture of f2.8 and a minimum aperture of f22 at 18mm, and a max aperture of f4.5 and minimum aperture of f36 at 50mm .
Sigma 18-50mm F2.8-4.5 DC OS HSM's optical formula consists of 16 elements in 12 groups.