| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection lens of improved optical quality such as a long back focus distance, a long exit pupil distance and a small F number. SOLUTION: The projection lens is provided with five optical groups OI to OV with respective effective focal distances fI to fV. The optical groups are moved on an optical axis so as to perform zooming and focusing. The projection lens is provided with at least 13 lenses L1 to L13 as a whole. The lenses are respectively provided with focal distance f1 to f13, Abbe's number V1 to V13, refractive index N1 to N13. The optical group OI is provided with lenses L1 to L3, the optical group OII is provided with lenses L4 to L5, the optical group OIII is provided with lenses L6 to L8, the optical group OIV is provided with a lens L9 and the optical group OV is provided with lenses L10 to L13. The lenses L10 to L12S are combined together so as to form a triplet.
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