US Patent 7869141 Compact fisheye objective lens

A compact fisheye objective lens comprising a series of six lens elements arranged on an optical axis to focus an image on an image plane, the compact fisheye objective lens having a first lens element with a convex object surface that faces the object and a concave image surface that faces image plane, and a second lens element spaced to the right of the first lens element concave image surface, the second lens element having a concave object surface and a concave image surface. The compact fisheye objective lens having singlet third and fourth lens elements, the fifth and sixth lens elements being combined to form a doublet having a positive power.