| 摘要 |
<p>PROBLEM TO BE SOLVED: To secure desired visibility while increasing the magnification of a magnifying glass.SOLUTION: An eyepiece optical system includes: a first lens having a biconvex shape in an optical axis center and having positive refractive power; a second lens having negative refractive power; a third lens having positive refractive power; and a fourth lens having positive refractive power. The first to fourth lenses are arranged in order from the side of an image to be observed. The following conditional expression is satisfied, 0.47<f3/f4<3.00 (1) where f3 is a focal length of the third lens, and f4 is a focal length of the fourth lens.</p> |
