Lens Sigma 18-35mm f/1.8 DC HSM Art - wide-angle lens is the first in the world with a constant maximum aperture of f / 1.8 for cameras with partial height APS-C sensor format. When installed on a SLR lens of this format will cover the range of effective focal lengths from 27 to 52.5 mm. The lens is great for landscapes, portraits, still life, studio shot, close-up shots and everyday photos.
The new lens uses internal focusing and zooming, so that the dimensions of the lens during use remain unchanged, and the front element does not rotate, which simplifies the use of polarizing filters. Other advantages include ultrasonic drive autofocus multilayer antireflection coating and aperture rounded with nine lobes.
Optical lens Sigma A 18-35 f / 1.8 DC HSM circuit consists of 17 elements in the groups 12, including molded aspherical lenses 4 and 5 of the elements with SLD low dispersion glass. Super multilayer coating reduces halos with glare and provides a high contrast even when the subject illumination.
The ultrasonic autofocus drive motor ring type with a constant possibility of manual correction (FTM) and an optimized AF algorithm enables quick and quiet focusing. In tests LensTip site, very high resolution - to open a small drop, hardly affects the DF, larger than the previous drop in resolution at the edges - but not more than 20%