Mark
The images were taken with a Canon 5d (full frame sensor)... the landscape images aren't cropped... square, cropped on the long side.
The Canon 15mm Fisheye produces a rectangular image which is heavily 'circularised' depending on the angle of shooting (if that makes sense).
It's a difficult lens to use... you just gotta slam it on the camera, set it to infinity focus (manual) and get on with it!