| 摘要 |
PROBLEM TO BE SOLVED: To obtain an imaging optical system that makes it easy to correct various aberrations including a chromatic aberration, has high optical performance, and what is more, to enable achievement of downsizing of an entire system, and light-weight of a lens weight.SOLUTION: A partial group St has one or more pieces of positive lenses, and let a focal length of a first lens group be f, a focal length of a second lens group be f, an entire length of a lens be L, a focal length of an entire system when focused on an object at infinity be f, a focal length of an i-th i positive lens when counted from an object side to an image side of the positive lenses be fPi, an Abbe number at d-line reference of a material consisting of the i positive lens and abnormal partial dispersion ratio be νand Δθ, and n be the total number (where, when the partial group st plurally exists) of the positive lenses included in the partial group St, and each value is appropriately set.SELECTED DRAWING: Figure 1 |
