| 摘要 |
PROBLEM TO BE SOLVED: To maintain excellent optical performance even under use environment where the temperature of the vicinity of a diaphragm position is extremely high, while satisfying both of making the angle wide and the size compact. SOLUTION: A wide-angle lens for projection has, in the order starting from the magnifying side, a first lens group G<SB>1</SB>having negative refractive power, a second lens group G<SB>2</SB>having positive refractive power, and a third lens group G<SB>3</SB>having positive refractive power; the first lens group G<SB>1</SB>comprises three negative lenses (first to third lenses L<SB>1</SB>to L<SB>3</SB>); the second lens group G<SB>2</SB>is configured to include a cemented lens obtained by cementing a positive fourth lens L<SB>4</SB>and a negative fifth lens L<SB>5</SB>in order from the magnification side. The third lens group G<SB>3</SB>includes five single lenses (ninth to thirteenth lenses L<SB>9</SB>to L<SB>13</SB>), having positive, negative, positive, negative and positive refractive powers in order from the magnification side, respectively. The diaphragm position is set in the third lens group G<SB>3</SB>. COPYRIGHT: (C)2011,JPO&INPIT |
