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
Allied Masonic Degrees Allied Masonic Degrees The Allied Masonic Degrees (AMD) are a series of Masonic degrees conferred by "Councils of the Allied Masonic Degrees". The Allied Masonic Degrees form an appendant order of Freemasonry that exists in some Masonic jurisdictions; its degrees are conferred only by invitation. Councils of the Allied Masonic Degrees exist in Great Britain, the United States, Canada, France and Australia and their members also educate one another by presenting research papers on Freemasonry. The structure is very like that of the craft lodges, with the exception that the offices of Secretary and Treasurer may be combined in some