This Canon 17mm TS-E is the widest in their tilt shift lineup. Of course, the glass is "L" quality and it has a maximum aperture of f/4. Great for architecture to keep the entire frame sharp or work in reverse for that wonderful selective focus.
Focal Length & Maximum Aperture
18 elements in 12 groups
Diagonal Angle of View
104° (without tilt or shift)
Image circle diameter
Manual focus, rear focusing system with focusing cam (with floating system)