Abstract: A catadioptric lens system includes: a first lens group including a concave mirror and a convex mirror and having positive refractive power; a second lens group having positive refractive power; and a third lens group having negative refractive power, the first to third lens groups being provided, in order, on a light path of incident light and in a direction of travel of the incident light.

Abstract: A zoom lens includes first to fourth lens groups having negative, positive, negative, and positive refractive power, respectively, and arranged in order from an object side. The first lens group includes negative lenses. The fourth lens group is configured of one positive lens. A zooming operation from wide end to telephoto end allows the first to third lens groups to travel along an optical axis, and allows the fourth lens group to be fixed. A focusing operation allows the third lens group to travel along the optical axis. The conditional expressions 1<(R1a+R1b)/(R1a?R1b)<5 and 2<(R4a+R4b)/(R4a31 R4b)<7 are satisfied where R1a and R1b are curvature radii on the object side and on the image side of a most-object-sided negative lens in the first lens group, respectively, and R4a and R4b are curvature radii on the object side and on the image side of the positive lens in the fourth lens group, respectively.

Abstract: A zoom lens includes first to fourth lens groups having negative, positive, negative, and positive refractive power, respectively, and arranged in order from an object side. The first lens group includes negative lenses. The fourth lens group is configured of one positive lens. A zooming operation from wide end to telephoto end allows the first to third lens groups to travel along an optical axis, and allows the fourth lens group to be fixed. A focusing operation allows the third lens group to travel along the optical axis. The conditional expressions 1<(R1a+R1b)/(R1a?R1b)<5 and 2<(R4a+R4b)/(R4a?R4b)<7 are satisfied where R1a and R1b are curvature radii on the object side and on the image side of a most-object-sided negative lens in the first lens group, respectively, and R4a and R4b are curvature radii on the object side and on the image side of the positive lens in the fourth lens group, respectively.

Abstract: A catadioptric lens system includes: a first lens group including a concave mirror and a convex mirror and having positive refractive power; a second lens group having positive refractive power; and a third lens group having negative refractive power, the first to third lens groups being provided, in order, on a light path of incident light and in a direction of travel of the incident light.