Along with its new full-frame digital SLR camera, the Sony Alpha DSLR-A850, Sony has also introduced a new lens, the Sony 28-75mm f/2.8 SAM, which is a standard zoom lens with a fast constant maximum aperture of f/2.8 made for the company’s range of full-frame digital SLR cameras. The solidly-built Sony 28-75mm f/2.8 SAM has an optical construction that consists of 16 elements in 14 groups including 3 LD elements, 4 aspherical elements, and 2 XR elements. It comes with 7 rounded aperture blades and supports 67mm non-rotating filters. Measuring 78 x 94 mm (3 x 3.7 in) and weighing only 565 g (20 0z), the Sony 28-75mm f/2.8 SAM is not only compact but also lightweight, it is actually one of the lightest lenses in its class.
As the name suggests, the Sony 28-75mm f/2.8 SAM uses a built-in SAM autofocus motor rather than the SSM autofocus motor used by the company’s more expensive Carl Zeiss Vario-Sonnar lenses. SAM is the abbreviation of Smooth Autofocus Motor, it is an in-lens autofocus technology developed by Sony in 2009, while SSM is the abbreviation of Supersonic-wave Motor, which is an in-lens autofocus system developed by Minolta in the late 1990s. Although the SAM is a less-expensive system, it still offers quick and accurate autofocusing. Both SAM and SSM are in-lens autofocus systems, which mean that the focusing is done by a motor inside the lens, not by a motor inside the camera body.
The Sony 28-75mm f/2.8 SAM’s focal length marks come at 28mm, 35mm, 50mm, 60mm, and 75mm, it also features a zoom lock which can only be set at 28mm. Zooming with the Sony 28-75mm f/2.8 SAM is very smooth and easy with appropriate dampening. It is also worth noting that the zoom movement only adds 34 mm (1.3 in) to the overall length of the lens. Overall, the Sony 28-75mm f/2.8 SAM is a high-quality standard zoom lens, suitable for use with high-end Sony digital SLR cameras. With a price tag of less than US$800.00, the Sony 28-75mm f/2.8 SAM is an excellent alternative to the Sony 24-70mm f/2.8 ZA SSM Carl Zeiss Vario-Sonnar T* lens (SAL2470Z).