Sigma APO 120-400mm F4.5-5.6 DG OS HSM Lens Review

A close cousin to the APO 150-500mm F5-6.3 DG OS HSM lens, which has also been reviewed on the Photo Review website, Sigma's APO 120-400mm F4.5-5.6 DG OS HSM lens can be used on both 'full frame' and 'APS-C-sized' DLSR cameras as well as traditional 35mm SLRs. Smaller and lighter than the 150-500mm model, it is a significant upgrade on the 135-400mm f/4-5.6 lens it replaces.
Key features of the new lens are the inclusion of Sigma's original OS (Optical Stabiliser) and the use of the company's HSM (Hyper Sonic Motor), which provides fast and quiet autofocusing as well as full-time manual focusing capability. Like its sibling, it is compatible with Sigma's APO Tele Converters.
The optical design is similar to the 150-500mm lens, with 21 elements arranged in 15 groups. Three SLD (Special Low Dispersion) glass elements have been included to correct chromatic aberration and super multi-layer coating is applied throughout the optical system to minimise flare and ghosting. For general photography, this lens has a minimum focusing distance of 150cm throughout the zoom range and delivers a maximum magnification of 1:4.2, making it useful for close-up photography.
A rear focusing system minimises the risk of image softening caused by focusing and ensures optimum image quality throughout the entire zoom range. The maximum apertures of f/4.5 at 120mm and f/5.6 at 400m are relatively large for 3.3x zoom lenses of this type.|
Build quality is similar to the 150-500mm lens. With a metal mounting plate and stylish matte black coating. Rubberised focusing and zoom rings ensure a secure and positive grip. As in the 150-500mm lens, the zoom ring is towards the front of the lens barrel with the focusing ring about mid-way back to the camera.
The zoom ring in broader and measures just under 28mm deep and its rubber coating has thicker ridges than those on the focusing ring, which is 18mm thick. The removable tripod collar fits behind the focusing ring. Just behind it is a distance scale with markings for metres and feet.
Just behind the zoom ring on the side of the barrel is a lock that prevents the lens from extending when carried on a downward-facing camera. Behind the focusing ring are two sliders, the top one switching between auto and manual focus modes and the lower one controlling the optical stabiliser. Full-time Two stabilisation settings are provided, along with an off position.
According to Sigma's website, the lens is supplied with end caps, a hood and a soft carrying case (although we received only the end caps with the review lens).

Margaret Brown

more : photoreview