SIGMA Lens Technology

Sigma Lens Technology

Lens Technology

Sigma lens development is dedicated to one thing: creating great photographs. The key is core technology research, which lets us refine our advanced processing and fabrication technology, while finding unconventional solutions to optics challenges. It is only when a lens can deliver an excellent image that you may appreciate features of mechanical design or control technology that support operational comfort and convenience. Technology should be dedicated to ever more faithfully capturing precious moments and beautiful scenes, with functionality commensurate with this ability. The scrupulous care with which we approach all facets of technology is reflected in the extraordinary quality of each and every Sigma lens. Each of Sigma’s more than 40 lenses incorporates original Sigma technology and expertise gained from decades of experience, guided by an uncompromising philosophy. Here we introduce Sigma's technology, developed and perfected to meet the varied and sophisticated needs of photographers while stimulating fresh photographic creativity.

Original technology minimizes secondary spectrum

Exclusive low-dispersion glass

The degree to which light is refracted (bent) by glass depends on the light’s wavelength (color). This fact causes different colors of light to focus at slightly different points. The result is chromatic aberration, the color fringing that is particularly noticeable in telephoto lenses. Most chromatic aberration can be removed by combining a high-refractivity convex lens element with a lowrefractivity concave element. But residual chromatic aberration known as “secondary spectrum” can only be corrected with selected lowdispersion glass materials.

Lens technology

In addition to ELD (Extraordinary Low Dispersion) glass and SLD (Special Low Dispersion) glass, Sigma uses FLD (“F” Low Dispersion) glass, which has the highly desirable anomalous dispersion characteristics of fluorite. Careful arrangement of these exclusive low-dispersion glass elements gives Sigma lenses superlative image rendition untarnished by residual chromatic aberration.

Focus systems for optimized performance

Inner and Rear Focus

In a conventional lens, focusing requires an extension of the entire lens or the front lens group. However, to better accommodate autofocusing mechanisms and closeup photography, a need has arisen for lenses that do not change their length during focusing or suffer from focus-dependent variation in aberration. Therefore, Sigma has developed focusing systems that only move elements within the lens barrel. These incorporate smaller and lighter moving lens elements which help improve auto-focus speed. With their unchanging barrel length and small variation in the center of gravity, these lenses also enhance balance and stability for the photographer. Furthermore, since the front of the lens does not rotate, polarizing filters can be used with extra convenience.

Lens technology

AF drive motor for rapid focusing and quiet operation

Hyper Sonic Motor (HSM)

The Hyper Sonic Motor (HSM) is an original Sigma development that uses ultrasonic waves to drive the autofocus mechanism. Its extremely quiet operation helps avoid disturbing photographic subjects. High torque and speed assure rapid auto-focus response. Sigma uses two types of HSM: Ring HSM and Micro HSM. The Ring HSM configuration permits manual fine tuning of focus (manual override) by turning a focusing ring after auto-focus operation.

Effective correction of spherical aberration and distortion

Aspherical Lens

Sigma’s aspherical lens technology contributes to outstanding optical performance and compact dimensions. These aspherical lens elements compensate for the spherical aberration and distortion which cannot be completely eliminated using conventional spherical lens elements alone. They are also key to reducing the size and weight of high-power zooms and other large lenses while improving image quality. Sigma has two kinds of aspherical lens technologies. Hybrid aspherical lens elements are made by forming a polymer in an aspherical shape on a glass lens surface. Glass mold aspherical lens elements are made by direct forming of the glass lens material.

Proprietary multi-layer coating technology to virtually eliminate ghosting and flare

Super Multi-Layer Coating

Sigma’s own Super Multi-Layer Coating suppresses flare and ghosting by preventing reflections within the lens. All DG and DC lenses in the current Sigma range feature this original technology. In digital cameras, flare and ghosting may also be caused by reflections between the image sensor and lens surfaces. Here too, Sigma’s Super Multi-Layer Coating is highly effective, assuring images of outstanding contrast.

Advanced focusing mechanism reduces lens movement and aberration variation

Floating System

This system adjusts the distance between lens groups while focusing, thereby reducing the amount of lens movement required. The result is less variation in aberration at different shooting distances. Benefits are particularly great in macro lenses because they cover a wide range of shooting distances, and in wide-angle lenses which employ asymmetric configurations of lens elements.

Lens technology

Designed to optimize bokeh near maximum aperture

Rounded Diaphragm

The polygonal shape of a conventional iris diaphragm causes outo-focus light points to appear polygonal. A rounded diaphragm is designed to produce rounded outo-focus light points when opened to near maximum aperture. This creates attractive bokeh effects in many situations, such as when photographing a subject against an out-of-focus surface of water from which light is being reflected.

Original Sigma technology counteracts camera shake

Optical Stabilizer (OS)

Sigma’s original Optical Stabilizer (OS) technology uses two sensors inside the lens to detect vertical and horizontal motion. By adjusting particular lens elements, the OS compensates for detected movement, thereby minimizing blur caused by camera shake. This can provide stabilization equivalent to using a shutter speed four stops faster. Since stabilization takes place within the lens, what you see in the viewfinder is the resulting stabilized image. This lets you confidently judge focus and composition. Two OS modes are available, depending on the lens. Mode 1 detects and corrects vertical and horizontal motion, ideal for shooting with the camera in a fixed position. Mode 2 detects and corrects only vertical motion, making it ideal for panning, as when shooting motor sports, for example.

Camera shake correction mechanism OFF

Camera shake correction mechanism OFF

Camera shake correction mechanism ON

Camera shake correction mechanism ON