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
180 Degrees South: Conquerors of the Useless of so many ecological horror documentaries on topics ranging from global warming to the corn syrup in our peanut butter." He writes "The regard for the planet shown in "180° South" comes from the quiet, philosophical nature of the people profiled in the film, who realize there is more adventure in the preservation of nature than in its conquering." "Minneapolis Star-Tribune" praised the film by writing "If you are this close to chucking it all in, packing your bags and going vagabond, by all means do not see "180° South." Director Chris Malloy's eco-tourist documentary could stoke your wanderlust to