| 摘要 |
A six element fisheye objective lens comprising a first lens element having a convex object surface facing the object and a concave image surface facing the image plane, a second lens element having a convex object surface facing the object and a concave image facing the image plan. A third lens element has a positive power. A positively powered lens group has a positively powered cemented doublet lens pair. A singlet lens element has a positive power, The lens group has an object surface facing the object and an image surface facing the image. The ratio of the total track to the focal length satisfies the condition that 8<TT/fo<15. The fisheye objective lens has an optical axis, the first, second, third and the lens group being coaxially aligned on the optical axis.
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