Sigma 120-400mm F4.5-5.6 DG HSM is an Auto Focus (AF)
Telephoto Zoom lens with 35mm FF max sensor coverage and it is designed to be used with Pentax KAF3 mount cameras.
Lens Mount
Sigma 120-400mm F4.5-5.6 DG HSM is compatible with cameras that have
Pentax KAF3 lens mount. Some of the latest released cameras with Pentax KAF3 lens mount are
Pentax K-3 III,
Pentax K-1 II and
Pentax KP.
Sensor Coverage
Max sensor coverage of Sigma 120-400mm F4.5-5.6 DG HSM is
35mm FF.
Focal Range
Sigma 120-400mm F4.5-5.6 DG HSM has a focal range of 120-400mm and 3.3X zoom ratio. When it is mounted on an APS-C sensor camera with 1.5x crop, it provides an 35mm (FF) equivalent of 180 - 600mm.
Optical Image Stabilization
Sigma 120-400mm F4.5-5.6 DG HSM doesn't have an optical image stabilization system so the only option to stabilize the image taken with this lens is to mount on a camera body with IBIS (sensor based In-body image stabilization).
Zoom Method
Sigma 120-400mm F4.5-5.6 DG 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.
Maximum Magnification Ratio
Sigma 120-400mm F4.5-5.6 DG HSM has a Max Magnification Ratio of
0.24x and has a minimum focusing distance of
1.5m.
Aperture
Sigma 120-400mm F4.5-5.6 DG HSM is a variable aperture lens with a max aperture of f4.5 and a minimum aperture of f22 at 120mm, and a max aperture of f5.6 and minimum aperture of f28 at 400mm .
Optical Formula
Sigma 120-400mm F4.5-5.6 DG HSM's optical formula consists of 21 elements in 15 groups.