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
Less than Angels with an air of detachment. Anne Wyatt-Brown writes that "Catherine represents Pym’s view of the world. She shares her author’s imagination, her amused reaction to anthropologists, and her detachment." Less than Angels Less Than Angels is a novel by Barbara Pym, first published in 1955. The novel is largely concerned with the activities of a group of anthropologists, and is to some extent based on the author's own experiences working at the International African Institute in London. It is set in a period of social change which is subtly represented within the novel's plot and setting Catherine Oliphant is a