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
Backstreet Boys: Larger Than Life making it the most attended residency in Las Vegas in terms of average audience. Encore: Clips from BACKSTREET BOYS – SHOW 'EM WHAT YOU'RE MADE OF feature film (c) Pulse Films/K Bahn LLC 2015 and BSB personal archives Special Thanks: Notes Backstreet Boys: Larger Than Life Backstreet Boys: Larger Than Life is the first concert residency by American vocal group Backstreet Boys, performed at Zappos Theater (formerly The AXIS Theater) in the Planet Hollywood Resort & Casino in Las Vegas, Nevada. The show had its opening night on March 1, 2017 and is scheduled to close on April 27, 2019