SIGMA 18-35mm F1.8 DC HSM is the first zoom lens ever to achieve a maximum aperture of f1.8 throughout the zoom range. It is a wide aperture, standard zoom-lens for digital single lens reflex camera's with APS-C size sensor's. The lens has a focal range equivalent to 27mm - 52.5mm in a 35mm format and it can cover the angles of view of multiple fixed focal length lenses. This wide aperture, standard zoom lens enables the photographer to expand creative possibilities on any occasion. Our Art line delivers high-level artistic quality Sigma is organizing all its interchangeable lenses into three product lines; Contemporary, Art and Sports. Designed with a focus on sophisticated optical performance and abundant expressive power, our Art line delivers high-level artistic expression. Developed with the maximum emphasis on artistic touch, they are designed to meet the expectations of users who value a creative, dramatic outcome above compactness and multifunction. Along with landscapes, portraits, still-life, close-up and casual snaps, they are perfect for the kind of photography that unleashes the inner artist. Ideal for studio photography, they offer just as much expressive scope when capturing architecture, starry skies, underwater shots and many other scenes. Excellent Usability A zoom lens is very convenient as it offers various angles of view just by rotating the zoom ring. However, the down side was that no zoom lens ever offered a faster aperture than f2.8 which led photographers to select fixed focal length lenses for brighter images. While the aperture value of prime lenses is superior to zoom lenses, their field of view is always the same, and therefore it was always necessary to carry many fixed focal length lenses. SIGMA 18-35mm F1.8 DC HSM is a new generation lens that can deliver images at f1.8 aperture throughout its focal length. The bright viewfinder is very helpful for checking the focus and composition of the image. If it is compared with a lens of F2.8, the faster shutter speed and the shallow depth of field of F1.8 further expands creativity. From wide to standard range this lens offers the excellent versatility and performance of multiple fixed focal length lenses. Fruit of cutting edge technology To achieve a wide zoom lens with a maximum aperture of f1.8, various technical problems need to be overcome. As the aperture value gets larger, the depth of focus becomes shallower, thus it makes the lens design extremely complicated in order to compensate for various distortions, such as spherical, axial chromatic and astigmatic aberration along with curvature of field. In order to compensate for astigmatic aberration across the entire focal range, we have relied on the experience and know how gained when designing our super wide angle zoom lenses such as SIGMA12-24mm F4.5-5.6 II DG HSM and SIGMA 8-16mm F4.5-5.6 DC HSM. In addition, the technological innovation at our Aizu factory also contributes to better lens production. It has enabled us to develop a wide glass-molded aspheric lens, and the incorporation of SLD (Special Low Dispersion) glass has optimized power distribution of the optical elements and compensated for various aberrations as well as curvature of field at the widest angle. Thanks to our knowledge of lens design accumulated over a long period of time plus the latest lens manufacturing techniques, SIGMA has finally made the dream of a zoom lens with F1.8 throughout its entire focal range come true. Convenient handling Convenient handling is achieved by incorporating internal focusing and zooming which prevents any change in the length of the lens when focusing and zooming. It is possible to use a specialist filter, such as a Circular Polarizer, as the front part of the lens does not rotate. Designed to minimize flare and ghosting Flare and ghosting were thoroughly measured and monitored from an early stage in the lenses development to establish an optical design which is resistant to strong incidental light such as backlight. The Super Multi-Layer Coating reduces flare and ghosting and provides sharp and high contrast images even in backlit conditions. Attaching the matched petal type hood, which is supplied, will provide extra protection from flare and ghosting. Minimum focusing distance of 28cm With a minimum focusing distance of 28cm and a maximum magnification ratio of 1:4.3, this lens is excellent for close-up photography. Hyper Sonic Motor The HSM (Hyper Sonic Motor) ensures a silent, high-speed AF function. Optimizing AF algorithm, smoother AF is achieved. It also enables full-time manual focusing capability which allows sensible focus adjustment by simply rotating the focus ring. Incorporating Rounded diaphragm The 9 blade rounded diaphragm creates an attractive round bokeh at large-aperture settings.