Sigma 20mm f/1.4 Art DG HSM Lens (for Nikon Cameras)
The world's first f/1.4 ultra-wide-angle lens for full-frame DSLRs.
With a focal length of 20mm and a f/1.4 aperture, the Sigma 20mm f/1.4 Art DG HSM Lens delivers outstanding large-aperture brightness and bokeh, delivering unprecedented visual experiences. Allowing the photographer to leverage the perspective provided by the wide -angle and the shallow depth of field provided by the large aperture, this lens is ideal not only for such ultra-wide-angle subjects as landscapes and starry skies, but also for snapshots in low light, indoor photography, portraits with a natural bokeh effect, and much more. Sigma has extensive experience in leveraging its advanced design capabilities and leading-edge technologies to craft large-aperture prime lenses that bring out the full potential of ultra-high-megapixel DSLRs.
Two aspherical glass elements minimize distortion throughout the entire image. It features two FLD ("F" Low Dispersion) glass and five SLD (Special Low Dispersion) glass elements to minimize transverse chromatic aberration, which is mainly visible around the edge of the image. Sigma's Super Multi-Layer Coating reduces flare and ghosting to help photographers produce sharp and high contrast images even in backlit conditions.
The Hyper Sonic Motor (HSM) ensures silent, high-speed autofocusing, while the optimized AF algorithm helps realize even smoother AF performance. The 9-blade rounded diaphragm creates an attractive blur in the out-of-focus areas of the image.
Delivers high-level artistic quality:
Designed with a focus on sophisticated optical performance and abundant expressive power, Sigma's Art line of lenses 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. Ideal for studio photography, they offer just as much expressive scope when capturing architecture, starry skies, portraits and many other scenes.
Advanced technologies make possible a 20mm f/1.4 lens:
To offer an ultra-wide-angle 20mm focal length and f/1.4 brightness at wide-open aperture, this lens incorporates a large double aspherical lens 59mm in diameter. Lenses of this type had been considered extremely difficult to manufacture, but Sigma took on the challenge to realize an f/1.4 ultra-wide-angle lens that fulfills the strict performance requirements of the Sigma Art line. What made this breakthrough possible were Sigma's advanced manufacturing technologies, which the company has developed over time by producing a wide range of ultra-wide-angle and large-aperture lenses. In turn, these advances made possible the Sigma 20mm f/1.4 DG HSM Art. Moreover, Sigma's advanced optical design minimizes distortion, transverse chromatic aberration, sagittal coma flare, and the reduction of brightness toward the edges of the image. Delivering top performance even at wide-open aperture, this lens can be considered the culmination of Sigma's Art line.
Minimized chromatic aberrations:
This lens minimizes chromatic aberrations, a common issue in large-aperture ultra-wide-angle lenses. It features two FLD ("F" Low Dispersion) glass and five SLD (Special Low Dispersion) glass elements to minimize transverse chromatic aberration, which is mainly visible around the edge of the image. The optimized lens power distribution helps minimize axial chromatic aberration. As a result, this lens delivers high image quality in every situation without color smearing, and its rendering performance is consistently sharp with high contrast.
Distortion is a common issue in wide-angle lenses, and it is not possible to correct it simply by changing the aperture value. For this reason, a lens must be designed from the start to minimize this issue. By adjusting the incidence angle of light starting with the first lens element and incorporating optimally positioned aspherical glass elements, the Sigma 20mm f/1.4 DG HSM Art lens minimizes distortion throughout the entire image.
Exclusive low-dispersion glass:
The degree to which light is refracted by glass depends on the light's wavelength. 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 low-refractivity concave element. Yet residual chromatic aberration known as "secondary spectrum" may still remain. To minimize this secondary spectrum, which can be a serious issue with conventional lenses, Sigma lenses feature up to three types of exclusive low-dispersion glass offering superior performance: ELD (Extraordinary Low Dispersion), SLD (Special Low Dispersion) and FLD ("F" Low Dispersion). In particular, FLD glass offers ultra-low dispersion in combination with high transmittance and the anomalous dispersion characteristics of fluorite. Meticulous deployment of these types of exclusive low-dispersion glass and optimization of power distribution gives Sigma lenses superlative image rendition undiminished by residual chromatic aberration.
Flare and ghosting reduction:
From an early stage in the lens design process, flare and ghosting have been measured to establish an optical design resistant to strong incident light sources such as backlighting. Sigma's Super Multi-Layer Coating reduces flare and ghosting to help photographers produce sharp and high contrast images even in backlit conditions. The included lens hood can be attached to block out extraneous light, which can have a negative effect on rendering performance.
Top-level performance for the ultra-high-megapixel era:
Since the Sigma 20mm f/1.4 DG HSM Art provides the benefits of an ultra-wide angle lens with minimal distortion, it is ideal for photographing landscapes, starry skies, and architecture. In addition to capturing wide-angle shots with the whole scene in focus, the photographer can leverage wide-open aperture to take snapshots with the subject in focus and the background blurred with an attractive bokeh effect. Designed for ultra-high-megapixel digital cameras, this high-performance lens delivers outstanding resolution and high-clarity image quality even at wide-open aperture.
A refined, integrated design made with the photographer in mind:
In Sigma's new product lines, the lens caps and AF/MF switches are designed to improve usability. To ensure precise operation, internal parts feature generous use of metal and Thermally Stable Composite (TSC), which is highly compatible with metal parts. The lens barrel is engraved with the year of release for instant access to this information.
Note: TSC offers thermal expansion characteristics similar to those of aluminum. Parts made with TSC deform less, making lens construction of extremely high precision possible. As compared to polycarbonate containing 20% glass, a commonly used material, TSC offers approximately 70% higher elasticity. As compared to polycarbonate containing 30% glass, it offers 25% higher elasticity. (comparison is between Sigma-produced components.)
Hyper Sonic Motor ensures high AF speed:
The Hyper Sonic Motor (HSM) ensures silent, high-speed autofocusing, while the optimized AF algorithm helps realize even smoother AF performance. At any time during AF, users may access MF simply by rotating the focus ring. This feature makes faster focus adjustment possible, since there is no need to use the AF/MF focus mode switch. Also, the optional Sigma USB DOCK allows the user to set the lens to conventional full-time manual focus override.
Metal lens cap available (sold separately):
Matching the high-quality finish of the lens exterior, optionally available metal lens cap LC907-02 will go on sale simultaneously with the lens. Featuring materials identical to those of the lens barrel, this metal lens cap establishes a new level of unity within Sigma's new lens lines.
The 9-blade rounded diaphragm creates an attractive blur in the out-of-focus areas of the image.
Brass made bayonet mount:
This lens incorporates a brass made bayonet mount which has both high accuracy and durability. A special treatment to reinforce its strength is applied to the surface giving it greater strength and making it highly resistant to long-term use.
"Made in Japan":
All Sigma's manufacturing processes -- right down to molds and parts, with a few exceptions -- are carried out under a single integrated production system entirely in Japan.
Evaluation with Sigma's own MTF measuring system "A1":
Sigma used to measure lens performance with MTF measuring system using conventional sensors. However, they have now developed a proprietary MTF (modulation transfer function) measuring system (A1) using 46-megapixel Foveon direct image sensors. Even previously undetectable high-frequency details are now within the scope of quality control inspections. This lens will be checked using this "A1" method before it is shipped.