
I’ve not seen an APS-C lens quite like Sigma 17-40mm f/1.8 DC | A since back in 2013, when the company took me by surprise and launched the Sigma 18-35mm f/1.8 DC HSM | A.
From the company’s ‘Art’ stable of lenses, it was built for APS-C format Canon and Nikon DSLRs, as well as Sigma's SA mount cameras. The fast and constant f/1.8 aperture made the lens feel (approximately) like a trilogy of 28mm, 35mm and 50mm prime lenses all rolled into one convenient package.