Zooming optical system, imaging optical device, and digital device

摘要

A zooming optical system has, from the object side, a positive first group, a negative second group, a positive third group, a positive fourth group, and a negative fifth group. During zooming, at least the third to fifth groups move relative to the image plane, and focusing is achieved by moving the fourth group along the optical axis. The conditional formula −1.0

主权项

1. A zooming optical system comprising, from an object side, a first group having a positive optical power, a second group having a negative optical power, a third group having a positive optical power, a fourth group having a positive optical power, and a fifth group having a negative optical power, the zooming optical system achieving zooming by varying axial distances between the individual groups, wherein
during zooming, at least the third, fourth, and fifth groups move relative to an image plane, focusing is achieved by moving the fourth group along an optical axis, and conditional formulae (1), (3) and (5) below are fulfilled:
−1.0 M4 represents a distance along the optical axis from a position of the fourth group at the wide-angle end to a position of the fourth group at the telephoto end; M5 represents a distance along the optical axis from a position of the fifth group at a wide-angle end to a position of the fifth group at a telephoto end; f3 represents a focal length of the third group; f4 represents a focal length of the fourth group; and f5 represents a focal length of the fifth group.