Upload & Sell: On
The manual focus Samyang UMC 14mm f/2.8 AS is worth a shot. It's relatively dirt cheap, very sharp, and has simple barrel distortion that's easy to quickly fix in PP. The Zeiss 18/3.5 ZE is very sharp, fairly expensive (but less than a TS-E 17/4L ), but it has moustache distortion that's not so easy to fix. Plug-ins are available, but I don't use them as my 18 ZE is mostly used for scenics, where you don't care so much. The Samyang 14mm cropped to a 17mm FOV has better IQ than both the EF 17-40L and Tokina AT-X Pro 17/3.5 AF; the AT-X is better than the EF at the edges and in the corners. I own or have owned all of the lenses mentioned above.