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 Many Birds How Many Birds "How Many Birds" is a song written by Barry Gibb, recorded by the Bee Gees in 1966 for the "Spicks and Specks" album. Recording took place at St. Clair Studios, Hurstville outside Sydney. The song was recorded on one-track tape machines and required the use of sound-on-sound for all overdubs. "How Many Birds" was recorded around April and May 1966 as part of the sessions for what became the Spicks and Specks album. The song starts with a guitar riff and the chord became E as Barry sings the introduction. After Barry sings the lines, the song