Ultra wide angle lens the difference is only whether distortion is present or not. However, the shorter the focal length, the more difficult it is to implement rectilinear correction. In fisheye lenses, the visual angle is close to or more than 180 degrees in at least one direction. For example, a "diagonal fish eye" would have a viewing angle of at least 180 degrees within the diagonals of the frame. A "circular fisheye" would represent the image in the form of a circle. Rectilinear ultra-wide angle lenses are used in photography and cinematography sometimes to achieve three-dimensional perspective distortion instead of simply two-dimensional barrel
How Are Things in Glocca Morra? made up by composer Lane, who had devised a dummy lyric beginning with the line, "There's a glen in Glocca Morra". Harburg liked the name but insisted on changing the line to "How are things in Glocca Morra?" because this is personal and immediately evocative of nostalgia and homesickness. James Stephens' work "The Crock of Gold" (first published in 1912) refers to "the leprechauns of Gort na Gloca Mora" ("the field of the big rock" in Gaelic). It is unknown whether Lane or Harburg were aware of the novel or if this is a coincidence. Many versions of this song