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
38 Degrees multi-issue movement. It aims to empower UK citizens by providing easy ways for them to take action on the issues they care about, e.g., climate change, human rights and poverty. It claims "it’s 38 Degrees members who set priorities and we decide on what we campaign on together". They publish the results of their membership polls on their website. While 38 Degrees refers to 'members', there is no formal membership and these are simply people on its email mailing list. Each week 50,000 members, chosen at random, are asked to vote for their top priorities; only ones where there is