yip i was wrong sorry. telestars is right. i found this trawling through the web - 'A rectilinear lens will preserve the straightness of lines throughout the frame, but objects at the edge become stretched, losing their proportion. These lenses are desirable for architecture. For normal appearances, keep people away from the edges.
An angular fisheye preserves the angle between two lines, but lines become increasingly curved at the edge of the frame. Subjects with recognized proportions, like people, will look best with this lens. For normal results, keep straight lines away from the edges.'