The 135L on 50MP fullframe.
Panasonic 12-60mm you mentioned few days ago?
Sony 50/1.8 on APS-C ?
http://flickr.com/ephankim
Could be much worse if it were 12/1.4?
actually could it be the Laowa Zero-D 12 mm f/2,8? (although the boarders would be really good for a 12mm 2.8 lens)