Abstract: An optical system includes, in order from an object side to an image side, a first lens unit having negative refractive power, an aperture stop, and a second lens unit having positive refractive power. The first lens unit includes a first lens having negative refractive power disposed closest to an object. The first lens has a meniscus shape that is convex to the object side. A predetermined condition is satisfied.

Abstract: A stereoscopic optical system includes two optical systems arranged in parallel. Each of the two optical systems includes a plurality of lens units that consist of, in order from an object side to an image side, a first lens unit having negative refractive power, a second lens unit, and a third lens unit having positive refractive power. The first lens unit includes a first reflective member disposed closest to an image plane. The third lens unit includes a second reflective member disposed closest to an object. The second lens unit includes a plurality of lens units that consist of, in order from the object side to the image side, a first subunit having positive refractive power and a second subunit having negative refractive power that are spaced by a widest air gap. The second subunit includes an aperture stop disposed closest to the image plane.

Abstract: A lens apparatus includes two optical systems each of which includes, in order from an object side to an image side, a negative first lens unit, a first reflective member, an aperture diaphragm, a second reflective member, and a positive second lens unit. Each optical system satisfies following inequalities: 5.9<DR/f<13.6 0.7<D2/f2<5.2 10.4<DP/f<19.8 DR represents a distance on an optical axis from a reflective surface of the first reflective member to a reflective surface of the second reflective member. f represents a focal length of the optical system. f2 represents a focal length of the second lens unit. D2 represents a distance on the optical axis from the reflective surface of the second reflective member to an image plane. DP represents a distance on the optical axis from the aperture diaphragm to the image plane.

Abstract: An optical system includes, in order from an object side to an image side, a first lens unit having negative refractive power, an aperture stop, and a second lens unit having positive refractive power. The first lens unit includes a first lens having negative refractive power disposed closest to an object. The first lens has a meniscus shape that is convex to the object side. A predetermined condition is satisfied.

Abstract: A lens apparatus includes two optical systems each of which includes, in order from an object side to an image side, a negative first lens unit, a first reflective member, an aperture diaphragm, a second reflective member, and a positive second lens unit. Each optical system satisfies following inequalities: 5.9<DR/f<13.6 0.7<D2/f2<5.2 10.4<DP/f<19.8 DR represents a distance on an optical axis from a reflective surface of the first reflective member to a reflective surface of the second reflective member. f represents a focal length of the optical system. f2 represents a focal length of the second lens unit. D2 represents a distance on the optical axis from the reflective surface of the second reflective member to an image plane. DP represents a distance on the optical axis from the aperture diaphragm to the image plane.

Abstract: An optical system consists of, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power. A distance between adjacent lens units changes during focusing. The second lens unit moves during the focusing. The following conditional expression is satisfied: ?0.20<f3/f<?0.05 where f is a focal length of the optical system focused on an object at infinity and f3 is a focal length of the third lens unit.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power, a distance between the first lens unit and the second lens unit changing during zooming. A predetermined condition is satisfied.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power, a distance between the first lens unit and the second lens unit changing during zooming. A predetermined condition is satisfied.

Abstract: A lens apparatus includes an optical system L0 including a plurality of lenses. The optical system L0 is changeable to a first state in which a focal length of the optical system L0 is a first focal length and a second state in which the focal length is a second focal length shorter than the first focal length, by changing one or some of the plurality of lenses. The maximum image heights and maximum angle of views in the first state and the second state are substantially constant and satisfy a predetermined condition.

Abstract: An optical system consists of, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power. A distance between adjacent lens units changes during focusing. The second lens unit moves during the focusing. The following conditional expression is satisfied: ?0.20<f3/f<?0.05 where f is a focal length of the optical system focused on an object at infinity and f3 is a focal length of the third lens unit.

Abstract: A lens apparatus includes an optical system L0 including a plurality of lenses. The optical system L0 is changeable to a first state in which a focal length of the optical system L0 is a first focal length and a second state in which the focal length is a second focal length shorter than the first focal length, by changing one or some of the plurality of lenses. The maximum image heights and maximum angle of views in the first state and the second state are substantially constant and satisfy a predetermined condition.