Scientific Photography and Applied Imaging

33 Fisheye lens photography

33.1 Imaging requirements

The usual demands for extreme wide-angle photography may be met by panoramic recording methods (Chapter 31), but the recording of subject matter filling a hemispherical or hyperhemispherical FOV usually requires use of a fisheye lense.

By reducing focal length relative to format diagonal, a wide angle lens gives an increase in FOV (2θ) to include more subject area from a given viewpoint. But for a lens with rectilinear or central projection as the image height (y) increases by the y = f.tanθ relationship, peripheral illumination reduces rapidly due to the cos⁴θ law of illumination, so that off-axis imagery may be of little use. Even retrofocus design and coma of the entrance pupil (Slussarev ...