The present disclosure relates to zoom lenses and optical devices using the same. A zoom lens may include in order from an object side to an image side: a first lens group, a second lens group, a third lens group, a fourth lens group; and a fifth lens group. The zoom lens may satisfy the following conditions: ?2.28?f.sub.2/f.sub.w??1.08, and 0.15?TTL/(BFL*f.sub.w)?0.45, wherein f.sub.2 denotes a focal length of the second lens group, f.sub.w denotes a focal length of the zoom lens at a wide angle end, TTL denotes a total track length of the zoom lens, and BFL denotes a back focal length of the zoom lens.

A lens barrel which reliably retracts a retractable lens group without increasing thickness in a direction of an optical axis before an adjoining lens group is housed. A first lens holding member holds a first lens. A cam cylinder drives the first holding member along the optical axis. At a shooting position, the second holding member that holds a second lens lies on an optical axis, and at a collapsed position, the second holding member retracts to a retracted position by engaging with a moving member that moves toward the image plane in response to movement of the cam cylinder toward the image plane. The cam cylinder has a cam groove, on which the first holding member moves toward a subject before the second holding member starts retracting in a process of shifting from the shooting position to the collapsed position.

A lens device includes a first lens system including a first lens, a second lens system including a second lens, a moving member configured to move in an optical axis direction of the first lens, and a physical structure configured to move the first lens in the optical axis direction and move the moving member in a direction opposite to a movement direction of a center of gravity of a physical system that includes the first lens.

Provided is an antireflection film that is formed by laminating an interlayer, a silver-containing metal layer containing silver, and a dielectric layer, in this order, on a substrate, in which the interlayer is a multilayer film having two or more layers, in which a layer of high refractive index having a relatively high refractive index and a layer of low refractive index having a relatively low refractive index are alternately laminated, and the dielectric layer has a surface to be exposed to air and is a multilayer film having two or more layers including an oxide layer and a fluorocarbon layer which is a self-assembled film that is formed by a silane coupling reaction to the oxide layer in this order.

A lens barrel including a first lens, an actuator that drives the first lens, a first barrel that holds a first cam follower and the actuator and moves in an optical axis direction, a second lens, and a second barrel that holds a second cam follower and the second lens and moves in the optical axis direction, the second barrel having a first hole portion in which the first cam follower is disposed.

An antireflection film is formed by laminating an interlayer, a silver-containing metal layer containing silver, and a dielectric layer in this order from the substrate, an anchor region including an oxide of an anchor metal is provided between the silver-containing metal layer and the interlayer, a cap region including an oxide of the anchor metal included in the anchor region is provided between the silver-containing metal layer and the dielectric layer, a crystal grain size obtained by X-ray diffraction measurement in the silver-containing metal layer is less than 6.8 nm, and the anchor metal has a surface energy less than a surface energy of silver and greater than a surface energy of a layer of the interlayer closest to the silver-containing metal layer.

A lens barrel which is miniaturized without complicating control over a drive unit which moves a plurality of optical members in a direction of an optical axis. A cam member is cam-engaged with each of a first optical member and a second optical member which move in the direction of the optical axis. The cam member is rotated about an axis parallel to the optical axis by a cam action of the cam member and the first optical member, which is driven to move in the direction of the optical axis by a linear actuator. Rotation of the cam member causes the second optical member to move in the direction of the optical axis due to a cam action of the second optical member and the cam member. The axis is arranged at an opposite position to the linear actuator with the optical axis as a center.

A method and apparatus for capturing an image of at least one object appearing in a field of view (FOV). A housing has an image sensor and a base lens assembly fixedly mounted relative thereto. A moveable lens assembly is movably mounted relative to the housing. The moveable lens, the base lens assembly, and the image sensor are aligned such that light received within the FOV passes through the moveable lens and the base lens assembly and impinges onto the image sensor. The light received from the FOV forms an original image prior to entering the movable lens and the base assembly. Light from the FOV impinging onto the sensor forms an impinging image.

A lens barrel in which tilt adjustment can be made depending on the position of a lens unit in the optical axis direction. This lens barrel includes: at least three guide bars provided so as to extend along the optical axis direction; a driving unit that respectively drives the at least three guide bars in the optical axis direction; a lens frame holding unit that holds an image-capturing lens, the lens frame holding unit being attached to at least three guide bars and being driven in the optical axis direction by the at least three guide bars; and a control unit that controls said at least three linear actuators so as to adjust the respective drive amounts in the optical axis direction of the at least three guide bars and to tilt the lens frame holding unit from a direction orthogonal to the optical axis.

A lens barrel in which tilt adjustment can be made depending on the position of a lens unit in the optical axis direction. This lens barrel includes: at least three guide bars provided so as to extend along the optical axis direction; a driving unit that respectively drives the at least three guide bars in the optical axis direction; a lens frame holding unit that holds an image-capturing lens, the lens frame holding unit being attached to at least three guide bars and being driven in the optical axis direction by the at least three guide bars; and a control unit that controls said at least three linear actuators so as to adjust the respective drive amounts in the optical axis direction of the at least three guide bars and to tilt the lens frame holding unit from a direction orthogonal to the optical axis.