The new Sigma 12-24mm F4.5-5.6 II DG HSM Lens For Canon Mount  is an update to the 12-24mm F4.5-5.6 EX DG ASP HSM. The new 12-24mm contains three glass mold elements, SLD and FLD to provide high image quality.
Sigma's new 12-24mm F4.5-5.6 II DG HSM Lens has been a photographer favorite since it was first introduced in 2002. Revisions to the lens include the inclusion of one Special Low Dispersion (SLD) glass element and four of the company's new "F" Low Dispersion FLD glass elements to compensate for color aberration and provide high image quality. FLD glass is the highest level, low dispersion glass available with extremely high light transmission and performance equal to fluorite glass. The new 12-24mm contains three glass mold elements and one hybrid aspherical lens for advanced performance and compact and lightweight construction. It also features Super Multi-Layer Coating to reduce flare and ghosting, and a Hyper Sonic Motor (HSM) to ensure quiet and high-speed autofocus, while allowing full-time manual focus override. Its minimum focusing distance is 11 inches throughout the entire zoom range; its maximum magnification ratio is 1:6.4.
- Ultra wide angle zoom superb optical performance
- FLD glass with performance equal to fluorite
- Carrying case, front adapter ring, front & rear caps
Ultra wide angle zoom lens compatible with digital SLR cameras with 35mm full frame image sensor.
This ultra wide angle zoom lens incorporates the latest optical design provides superior performance. FLD ("F" Low Dispersion) glass elements, which have performance equal to fluorite, and SLD (Special Low Dispersion) glass elements provide excellent correction of color aberration. Aspherical lenses give advanced performance with a compact and lightweight construction. The Super Multi-Layer Coating reduces flare and ghosting. High image quality is assured throughout the entire zoom range. Incorporation of HSM ensures quiet and high speed autofocus as well as full-time manual focus capability. This lens has superior peripheral brightness and provides sharp and high contrast images even at the maximum apertures.
Sigma designed and produced the first wide-angle zoom lens, the "zoom gamma 21-35mm F3.5-4", in 1979. Sigma has since introduced a number of wide angle zoom lenses. This ultra wide angle zoom lens is ideal for digital SLRs with a 35mm full frame image sensor and incorporates the latest optical design.
Superior image quality
The ultra wide angle zoom lens is possible due to large diameter of the front lens. Four FLD ("F" Low Dispersion) glass elements, which have performance equal to fluorite, and one SLD (Special Low Dispersion) glass element provide excellent correction of color aberration. Three glass mold elements and one hybrid aspherical compensate for all types of aberration and ensure high optical performance.
*FLD glass is the highest level low dispersion glass available with extremely high light transmission. This optical glass has a performance equal to fluorite glass which has a low refractive index and low dispersion compared to current optical glass. It also benefits from high anomalous dispersion. These characteristics give excellent correction for residual chromatic aberration (secondary spectrum) which cannot be corrected by ordinary optical glass and ensures high definition and high contrast images.
Super Multi-Layer Coating
Due to the ultra wide angle, the front of this lens is very large. Sigma's Super Multi-Layer Coating reduces flare and ghosting which could otherwise create problems when extraneous light hits the lens' front element. It also provides sharp and high contrast images throughout the entire zoom range.
Superior peripheral brightness
The design of front lens group minimizes light fall off and increases peripheral brightness.
The wide-angle of view produces striking images with exaggerated perspective, enabling photographers to emphasize the subject.
Incorporation of four aspherical lenses provides a compact construction with a diameter of 85mm (3.3"), overall length of 120.2mm (4.7") and weight of 670g (23.6oz.). The compact construction makes this lens ideal for travel photography.
Quiet and high speed autofocus
Incorporation of HSM (Hyper Sonic Motor) ensures quiet and high speed autofocus, while allowing full-time manual focus override.
Inner focusing system
This lens incorporates an inner focusing system, which eliminates front lens rotation which also minimizes fluctuation of aberration caused by the focusing system.
This lens is equipped with a Petal-type hood to block out extraneous light and reduce internal reflections.