The from delivers crisp, clear and non-distorted images with a versatile set of wide-angle focal lengths. It is a lens often found in the kits of working photojournalists due to its comprehensive wide-angle coverage, relative light weight and durability. On DX format DSLRs it provides the 35mm focal length equivalence of 24-52.5mm. The optical design features 17 lens elements in 12 groups and includes 2 Extra-low Dispersion (ED) and 3 aspherical elements to reduce chromatic aberrations and distortion and lend high contrast images. Nano Crystal Coating virtually eliminates internal lens element reflections across a wide range of wavelengths and reduces flare and ghosting.