| 摘要 |
PROBLEM TO BE SOLVED: To provide a wide angle lens for projection having such brightness that an aperture ratio is about 1:4.0 and achieving a projection angle such as 120 degrees or more. SOLUTION: In the wide angle lens for projection, a first lens group G<SB>1</SB>and a second lens group G<SB>2</SB>are arranged in order from a projection surface side. The first lens group G<SB>1</SB>is constituted of three negative lenses and a cemented lens obtained by bonding a negative lens and a positive lens, and has negative power. The second lens group G<SB>2</SB>is constituted of a negative lens, three positive lenses, a cemented lens obtained by bonding a negative lens and a positive lens, and a cemented lens obtained by bonding two positive lenses and a negative lens, and has positive power. The first lens group G<SB>1</SB>includes at least one aspherical lens. The wide angle lens satisfies a conditional expression (1) 0.3≤¾F<SB>1</SB>/F<SB>2</SB>¾≤1.3 (provided that F<SB>1</SB>: synthetic focal distance of the first lens group and F<SB>2</SB>: synthetic focal distance of the second lens group). COPYRIGHT: (C)2008,JPO&INPIT
|
