| 摘要 |
PROBLEM TO BE SOLVED: To obtain a satisfactory optical performance while having a small F number and a wide projection angle, in a projecting optical system. SOLUTION: The projecting optical system 100 includes, in order from a long conjugation side, a first lens group G1 with negative refractive power and a second lens group G2 with positive refractive power. The first lens group G1 includes: a plurality of negative lenses; and a positive lens 4B made of a glass material with a refractive index of 1.9 or greater. The second lens group G2 includes: a diaphragm 8; and an aspherical lens 9 with at least one aspherical face and negative refractive power. The aspherical lens 9 is disposed adjacent to the diaphragm 8 at the short conjugation side. COPYRIGHT: (C)2011,JPO&INPIT |
