Sigma 18-35 mm f1.8 lo zoom DX professionale

Fa parte della linea ART proprio come il 35mm 1.4, questo farebbe pensare ad un obiettivo che privilegia le prestazioni, e solo su formato APSC, ma indica la chiara intenzione di Sigma nel voler coprire tutti i segmenti abbandonati dai produttori principali, in questo caso gli zoom ad alte prestazioni per APSC.

Lo schema ottico


la messa a fuoco


Vignettatura


Distorsione


MTF



Un po di specifiche:
17 lenti in 12 gruppi
passo filtri 72 mm
angolo di campo 76.5° - 44.2°
Minima distanza di messa a fuoco : 28cm
Dimensioni : 78x 121mm
diaframma a 9 lamelle
rapporto di ingrandimento 1:4.3
peso 810g

Comunicato stampa :

RONKONKOMA, NY, Apr. 18, 2013 — Sigma Corporation of America , a leading researcher, developer, manufacturer and service provider for some of the world's most impressive lines of lenses, cameras and flashes, today announced the Sigma 18-35mm F1.8 DC HSM Art lens, the market’s first zoom lens to achieve a maximum aperture F1.8 throughout the entire zoom range.
This revolutionary, wide aperture, standard zoom lens is created for DSLR cameras with APS-C size sensors, which translates to a focal range of 27-52.5mm on a 35mm camera. With a minimum focusing distance of 11 inches, and a maximum magnification ratio of 1:4.3, the 18-35mm is ideal for landscapes, portraits, still-life, studio, close-up and casual photography.
"Exceptionally fast apertures were previously unavailable in zoom lenses, so photographers turned to several prime lenses in a session to get bright images at various focal lengths. We're incredibly excited to be the first manufacturer to bring the F1.8 standard zoom to the market and to provide photographers with a new level of creativity and convenience, with the outstanding image quality at the core of the new Sigma Global Vision," said Mark Amir-Hamzeh, president of Sigma Corporation of America.
Amir-Hamzeh added that because developing a large aperture wide angle zoom lens can prove to be technologically and optically challenging, often resulting in various distortions, aberrations and field curvature, Sigma has tapped into its long history as a lens pioneer to overcome those issues in this new generation lens.
"Our experience with the wide angle designs of our 12-24mm F4.5-5.6 II DG HSM and our 8-16mm F4.5-5.6 DC HSM, and our research and development in our Aizu factory have prepared us for this technological advancement,” he said. “Our wide, glass-molded aspherical lens and the incorporation of Special Low Dispersion (SLD) glass have optimized power distribution of the optical elements and compensated for various aberrations, as well as curvature of field at the widest angle. We’re extremely proud of this achievement."
The 18-35mm is the latest addition to the company’s company’s Art line of lenses, designed under the new Global Vision. The Global Vision lenses have a sleek new design with the manufacturing year stamped on the barrel, and are categorized by use into one of three groups: Art, Contemporary and Sports. The Art category delivers high-level artistic expression through sophisticated and abundant expressive power.
The new 18-35mm lens incorporates Sigma’s improved AF/MF switch and the use of Thermally Stable Composite (TSC) compound material, which has a high affinity to metal parts, consistently performs well at extreme temperatures, and reduces the size and weight of the lens. It is also compatible with Sigma’s new USB Dock, which will be available in coming months, enabling photographers to update lens firmware and adjust focus parameters from their computers.
Convenient handling is achieved with internal focusing and zooming, which prevents changes to the size of the lens. Additionally, the front part of the lens does not rotate, so special filters like circular polarizers can be used.
The 18-35mm lens’ Super Multi-Layer Coating reduces flare and ghosting and provides sharp and high contrast images, even in backlit conditions. The petal-type hood that is supplied with the lens will provide extra protection from flare and ghosting. Sigma’s Hyper Sonic Motor (HSM) ensures a silent, high-speed AF function and the optimized auto focus algorithm results in smooth focusing and full-time manual focusing capability. Lastly, the nine-blade, rounded diaphragm creates an attractive, round bokeh at large-aperture settings.