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Sigma 28-70mm F2.8 EX DG -- A Pro-Caliber lens

Sigma Corporation, a Japan based company best known for producing lenses, optical equipments and other photographic accessories. Sigma 28-70mm F2.8 EX DG SLR (Single Lens Reflex) lens is a well built and well specified lens with a decent price. This lens is very sharp having good construction.

The size of this lens will be 2.9 inch x 3.4 inch (74mm x 87.2mm). The focal length range is 28-70mm. It has f/2.8 aperture zoom lens and is excellent for digital SLR cameras. It includes canon AF mount. This lens gets constructed with a combination of 14 elements in 12 groups. It includes two SLD (Special Low Dispersion) glass elements and four aspherical lenses which provide ultimate correction against distortion and all types of aberrations, especially spherical aberration.

The maximum close-up photography magnification is 1:4.4. This lens has a special low dispersion glass for higher image quality. It has an internal focusing. This Lens does not support full-time manual focusing. The focus ring physically turns during autofocus. The autofocusing is fast and accurate on stationary subjects. The filter size diameter is 67mm. The angle of view of this lens will be 75.4 degree to 34.3 degree. Sigma 28-70 has a petal type of hood which is excellent for blocking the unwanted light as the front barrel of this lens does not rotate during focusing. It also includes a circular polarizing filter.

Chromatic Aberrations CA are under control and this lens has no flare. The minimum focusing distance of this lens is 13 inch (33 cm). Sigma 28-70 has a maximum magnification of .23x. At the universal close focus distance (12 inches), the magnification ratio of this lens ranges from 1:7.7 at 28mm to 1:4.5 at 70mm. Sigma 28-70 has no zoom creep. It has a nice torque. This lens has advanced optical design which ensures high performance over the entire zoom range. This lens weighs 510g (18 ounces).

The Sigma 28-70 has some flaws also. It has a noisy autofocus. The resistance of zoom ring is not consistent. It has a high contrast. This Sigma 28-70mm F2.8 EX DG SLR lens is available in Canon, Pentax, Minolta, Nikon and Sigma mounts. This lens is not so heavy and very comfortable to hold. Sigma 28-70 is a sharp, compact and outstanding lens for all users.

dbal
Sat, 12 Dec 2009 19:31:18 +0000

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