ZEISS Loxia 2.8/21
Here's what ZEISS says about this glass: "Despite its compactness, the super wide-angle ZEISS Loxia® 2.8/21 offers outstanding image performance – across the entire image field of a full-frame sensor. Whether architecture, landscape or also three-dimensional subjects in close-up against a spacious background – this focal length with its large image angle is an excellent addition to the Loxia lens family. It is an absolute must for wide-angle fans who want to capture even the tiniest details of a special moment in a photo or on film."