This lens covers all the focal lengths from 28mm wide angle to 200mm telephoto, the most frequently used focal length range. With a maximum diameter of 70mm (2.75 in.) and length of 77.7mm (3 in.), it has a compact size. And with a triple-cam internal-focus system, it packs a lot of performance in a compact package. Portable and mobile, the lens can be carried anywhere, so it is ideal for travel and snapshot photography.
With 2 aspherical lenses, it has excellent correction for all types of aberration, and it displays a high level of optical ability throughout the entire zoom range. The inner focus system allows the lens to be focused without having to rotate the front of the lens, and the lens accepts a Petal-type hood and it is also easy to use a circular polarizing filter.
High-performance zoom lenses, although offering a wide range of use, have one drawback: they are hampered by their size and weight when they have to be carried around. Smaller and lighter lenses are in demand, therefore, especially for travel photography, when space inside a camera bag or hand bag is at a premium. In order to achieve a compact lens, Sigma has combined a high-refractive-index, low-dispersion lens and aspherical lenses. The result is a compact lens only 70mm (approximately 2.70 in.) in diameter and 77.7mm (3 in.) in length. And by equipping the lens with the triple-cam internal-focus system, it achieves high performance in a small package.
The aspherical lens contributes more than compact size: it also delivers improved image quality. The front lens group has excellent correction for distortion at the wide-angle setting, and the rear lens group effectively corrects for spherical aberration, coma aberration, and astigmatic aberration throughout the entire zoom range.
The new DG multi-layer lens coating and lens design reduces flare and ghosting, and creates an optimium color balance resulting in better picture quality. This adds up to a lens with outstanding optical ability.
Because of the inner focus system, the front barrel does not have to rotate to focus the lens, and a circular polarizing filter can be easily used. In addition, a Petal-type hood can be mounted on the lens to give optimum protection from flare.
At the 200mm telephoto setting, the lens is capable of macro photography with a 1:3.8 maximum magnification. The minimum focusing distance is 48cm at all zoom settings. And with a photography magnification scale displayed on the lens barrel, the lens is user friendly.
A zoom lock switch mechanism is provided to prevent the lens from creeping due to its own weight, and to avoid the danger of the lens receiving a shock while it is being carried.