The long-awaited first macro lens in the Art line
Design prioritizing optical performance
In order to realize top-level performance at every shooting distance, the lens features an extending, floating, two-group focus mechanism. This configuration minimizes aberration to produce optimal results at any focus distance. To minimize axial chromatic aberration, the optical system incorporates two FLD glass elements, two SLD glass elements, and one element with a high rate of anomalous partial dispersion and a high index of refraction. In addition, two aspherical lens elements help increase resolution at close shooting distances. This optical system makes possible a razor-sharp in-focus area contrasted with a bokeh area free of colour streaking.
Designed to minimize flare and ghosting
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.
Exclusive low-dispersion glass
The degree to which light is refracted by glass depends on the light's wavelength. This fact causes different colours of light to focus at slightly different points. The result is chromatic aberration, the colour 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.
Focus-by-wire system for comfortable and precise focusing
The focus-by-wire system eliminates the direct mechanical connection between the focus ring and the focus drive system. Controlled by SIGMA’s latest algorithm, a newly developed coreless DC motor adjusts focus with optimal speed and low noise. Full-time manual focus is available even during autofocus, allowing the photographer to make minute focus adjustments simply by turning the focus ring. In addition, the focus ring’s large angle of rotation helps the photographer achieve the extremely precise focusing required for effective macro photography.
