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
The Three Degrees at The Royal Albert Hall" (aka "An Evening with The Three Degrees"), was recorded in October 1979 in which the trio were backed by the Royal Philharmonic Orchestra. In 1980, the compilation album "Gold" was released and became a UK Top 10 hit. Featuring one side of their hits on the Ariola label between 1978–79, and one side of live recordings from their 1979 Royal Albert Hall television special, this would be the trio's second "best of" compilation to make the UK Top 10 in less than two years, after CBS released "A Collection of their 20 Greatest Hits" in