I've been tasked with finding a lens wider than 24mm for our 5D Mark III. I'd be open to using a zoom, but it would need to be sharp. Currently, I'm thinking an 18mm or 14mm. We are strictly using this lens for video, so I'd prefer to stay away from still lenses, unless it is a REALLY amazing lens that holds up with minimal breathing. So...best EF Mount prime (18mm or 14mm)...ready...GO!