| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact and high-performance telephoto lens having a large diameter and a focusing group reduced in weight, and also provide an imaging optical device including the same and a digital device.SOLUTION: A telephoto lens LN includes, in order from the object side, a positive first group Gr1, a negative second group Gr2, a positive third group Gr3, and a positive or negative fourth group Gr4. When focusing from a subject infinite state POS1 to a subject most approximate state POS3, the first group Gr1 is fixed, the second group Gr2 is moved, the third group Gr3 is moved toward the object side, and the fourth group Gr4 is fixed. The second group Gr2 is composed of a single lens. The third group Gr3 is composed of a single lens or a cemented lens comprising a negative lens and a positive lens. The telephoto lens LN satisfies the following conditional expression: -2<f2/f3<-1.15, where f2 is the focal length of the second group Gr2, and f3 is the focal length of the third group Gr3. |
