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
How Not to Be Wrong How Not to Be Wrong How Not to Be Wrong: The Power of Mathematical Thinking, written by Jordan Ellenberg, is a "New York Times Best Selling" book that connects various economic and societal philosophies with basic mathematics and statistical principles. "How Not to Be Wrong" explains the mathematics behind some of simplest day-to-day thinking. It then goes into more complex decisions people make. For example, Ellenberg explains many misconceptions about lotteries and whether or not they can be mathematically beaten. Ellenberg uses mathematics to examine real-world issues ranging from the fetishizing of straight lines in the reporting of obesity to