| 摘要 |
Provided is an observation optical system including: an objective lens; an image inverting unit; and an ocular lens, the objective lens including, in order from object side to observation side: a positive first lens unit; a negative second lens unit; and a positive third lens unit, wherein the first lens unit consists of a positive front unit and a positive rear unit separated by an air interval, which is largest along optical axis, wherein the second lens unit moves to have a component orthogonal to optical axis for image blur correction, and wherein a lateral magnification of second lens unit, a curvature radius of a lens surface of second lens unit closest to observation side, a curvature radius of a lens surface of third lens unit closest to object side, the air interval between front and rear units, and a focal length of first lens unit are appropriately set. |
| 主权项 |
1. An observation optical system for observing an object image enlarged by an ocular lens, the observation optical system comprising:
an objective lens; an image inverting unit configured to invert an object image formed by the objective lens to an erect image; and the ocular lens configured to enlarge the erect image, the objective lens comprising, in order from an object side to an observation side:
a first lens unit having a positive refractive power, which is configured not to move for image blur correction;a second lens unit having a negative refractive power, which is configured to move for image blur correction; anda third lens unit having a positive refractive power, which is configured not to move for image blur correction, wherein the first lens unit consists of, in order from the object side to the observation side, a front unit having a positive refractive power and a rear unit having a positive refractive power, which are separated by an air interval, which is a largest air interval in a direction of an optical axis, wherein the second lens unit is configured to move so as to have a component in a direction orthogonal to the optical axis for image blur correction, and wherein the following conditional expressions are satisfied:
2.0≦|β2|≦10.0;−0.5(G3R1+G2R2)/(G3R1−G2R2)0.5; andd/f1>0.1,where β2 represents a lateral magnification of the second lens unit, G2R2 represents a curvature radius of a lens surface of the second lens unit that is closest to the observation side, G3R1 represents a curvature radius of a lens surface of the third lens unit that is closest to the object side, d represents the air interval between the front unit and the rear unit on the optical axis, and f1 represents a focal length of the first lens unit. |
