Fisheye distortion

Fisheye lenses have limited use.  However, there is one particular scenario where fisheyes do a great job. When photographing something circular in shape such as the dome inside the tombs of the Medici family in Florence, Italy, there is no apparent distortion.  This happens because fisheyes bend lines into a curvature, but if the subject is already round, there appears to be no distortion at all.  However, even though there is no apparent distortion, the unique look of a fisheye produces a different kind of image than a rectilinear wide angle. It's hard to put into words; you just have to see it to recognize the difference. I shot this in 1991 when I was still using a film camera.  I used a Mamiay RZ 67 with a 37mm fisheye, Fujichrome Velvia 100, and a tripod.  This is equivalent to about an 18mm fisheye lens.  I didn't record the settings, but knowing how I used to shoot with this medium format camera, they were probably f/4.5 and 1/4 second.  Note the blown out  windows.  We didn't have HDR then.