| 摘要 |
PROBLEM TO BE SOLVED: To provide an imaging lens system which is capable of focusing without changing a total length of an optical system and offers a wide half view angle of approximately 32 to 33 degrees, a low F value of approximately F2.5, a compact optical system with a total length of approximately 2.2 times an image height, a small variation of distortion aberration while focusing, and high performance.SOLUTION: An imaging lens system includes a first lens group Gr1 having positive refractive power, a second lens group Gr2 having negative refractive power, and a third lens group Gr3 having positive refractive power, arranged in order from the object side. The first lens group Gr1 comprises an aperture stop AD and five lenses. The second lens group Gr2 comprises a lens L6 having low refractive power and a negative lens L7 having a concave surface on the object side. The third lend group Gr3 comprises a positive lens L8 having a convex surface facing an imaging plane. The entire optical system comprises eight lens elements or less. |
