ABSTRACT
Image illumination is acceptably uniform, especially at small apertures. The curvature and protrusion of the anterior surface of the lens and its resemblance to a fish eye has led to the name fisheye lens, but the imagery also approximates to what is seen of the exterior scene by a fish through ‘Snell’s window’. The use of appropriately designed fisheye lenses underwater is advantageous in that even the reduced field angle of view is considerable and edge distortion is acceptable. The use of fisheye lenses and fisheye attachments to produce panoramic photos by selective enlargement is described by D. Richards. The use of a fibre-optic taper to reduce the image circle of a fisheye lens from 23 to 10 mm diameter to suit a charge coupled devices array for whole-sky photography is described by G. Grant. Depending on lens coverage and orientation of the optical axis, large areas up to full hemispherical coverage is possible.
