This full aperture series comparison includes HD and UltraHD images from f/2 through f/16 along with analysis of performance and large crops. In DAP:
Sigma SD1 Merrill + Sigma 35 Sigma 18-35mm f/1.8 @ 18mm (Water-Worn Rocks)
Also added is a page on correcting color fringing for the 18-35mm f/1.8 zoom.
Sigma SD1 Merrill + Sigma 18-35mm