Sigma 18-35mm f/1.8 DC HSM A

The Sigma 18-35mm f/1.8 DC HSM Art lens is a fast, constant-aperture wide standard zoom lens made by Sigma Corporation. It was announced April 18, 2013.
This lens, at its time of manufacturing, was the only standard zoom with a constant f/1.8 aperture. The lens was designed specifically for crop body DSLRs enabling a crop factor adjusted of f/2.88 for Canon or f/2.7 for Nikon crop body DSLRs across an equivalent range of 28mm-56mm or 27mm-53mm.
In the year of its introduction, the lens won an EXC!TE award and was named Lens of the Year at the Camera Grand Prix.