| 摘要 |
Lens apparatus includes adjacent concave and convex lens surfaces adjacent with an air layer therebetween. At least one of the lens surfaces includes an antireflection film including multiple subwavelength structures at an average pitch of 400 nm or smaller. The surface satisfies: 0.7<R1/R2<1.3, and |&thetas;2−&thetas;1|>15°, provided that: D=f/FNo, &thetas;1=sin−1(D/(2×fi)), and &thetas;2=sin−1((h×D)/R2), where f and FNo represent focal length and F-number of the entire optical system, f1 represents focal length of an optical system on object side with respect to the air layer between the lens surfaces, h represents axial conversion beam height on the at least one surface having anti-reflection film, R1 and R2 represent curvature radii of surfaces of respective object and image sides between the lens surfaces. |
