A system for adjusting an optical path length includes: a camera body; an image sensor coupled to the camera body; a first optical device coupled to the camera body; and a second optical device coupled to the camera body. At least one of the first and the second optical devices are movable relative to the camera body. The optical path length between the image sensor and the camera body opening is continuously adjusted by movement of the at least one of the first and the second optical devices relative to the image sensor. As the at least one of the first and the second optical devices move relative to the image sensor, the first optical device is in continuous contact with the second optical device.

A system for adjusting an optical path length includes: a camera body; an image sensor coupled to the camera body; a first optical device coupled to the camera body; and a second optical device coupled to the camera body. At least one of the first and the second optical devices are movable relative to the camera body. The optical path length between the image sensor and the camera body opening is continuously adjusted by movement of the at least one of the first and the second optical devices relative to the image sensor. As the at least one of the first and the second optical devices move relative to the image sensor, the first optical device is in continuous contact with the second optical device.

A rear attachment lens according to the aspect of the embodiments is configured to vary a focal length of a system by being attached to an image side of a master lens. The rear attachment lens includes a positive lens arranged closest to the image side in which a lens surface on the image side of the positive lens has a shape convex toward the image side. A focal length of the rear attachment lens, a magnification of the rear attachment lens when attached to the master lens, and a distance from the lens surface on the image side of the positive lens to a rear principal point position of the rear attachment lens when attached to the master lens are appropriately set.

A rear attachment lens according to the aspect of the embodiments is configured to vary a focal length of a system by being attached to an image side of a master lens. The rear attachment lens includes a positive lens arranged closest to the image side in which a lens surface on the image side of the positive lens has a shape convex toward the image side. A focal length of the rear attachment lens, a magnification of the rear attachment lens when attached to the master lens, and a distance from the lens surface on the image side of the positive lens to a rear principal point position of the rear attachment lens when attached to the master lens are appropriately set.

A system for adjusting an optical path length includes a camera body having a camera body opening, an image sensor coupled to the camera body, and an optical device movably coupled to the camera body. The movable coupling of the optical device to the camera body includes a first coupling position of the optical device relative to the camera body and a second coupling position of the optical device relative to the camera body. In the first coupling position, the optical device is located at a position that intersects a path between the image sensor and the camera body opening. In the second coupling position of the optical device, the optical device is located at a position that does not intersect the path between the image sensor and the camera body opening.

A system for adjusting an optical path length includes a camera body having a camera body opening, an image sensor coupled to the camera body, and an optical device movably coupled to the camera body. The movable coupling of the optical device to the camera body includes a first coupling position of the optical device relative to the camera body and a second coupling position of the optical device relative to the camera body. In the first coupling position, the optical device is located at a position that intersects a path between the image sensor and the camera body opening. In the second coupling position of the optical device, the optical device is located at a position that does not intersect the path between the image sensor and the camera body opening.

The anamorphic objective lens systems (100LS) and methods for forming a set of anamorphic objective lens assemblies (100(i)) having different focal lengths (FLY) and that utilize a front anamorphic section (20) and a set of two or more non-anamorphic sections (50(i)). The non-anamorphic sections are optically matched to the front anamorphic section and their front ends (52) are configured to be easily attached to and detached from the back end (24) of the front anamorphic section to create the anamorphic objective lens assemblies having the different focal lengths. Because the anamorphic objective lens system uses only a single front anamorphic section and multiple non-anamorphic attachments, the cost of having multiple anamorphic objective lens assemblies is substantially reduced as compared to using individual anamorphic objective lenses for each of the desired focal lengths.

A zoom lens includes, in order from an object side to an image side: a focus lens unit configured to be moved for focusing on an optical axis; a zoom lens unit configured to be moved for zooming on the optical axis; and a relay lens unit, in which an interval between each pair of adjacent lens units is changed for zooming, and the zoom lens includes an aperture stop arranged between the zoom lens unit and the relay lens unit or within the relay lens unit, the relay lens unit includes an extender lens unit insertable into and removable from an optical path of the relay lens unit, in which the extender lens unit includes a negative lens Lm which is an m-th lens from the object side in the extender lens unit and having a refractive index and an Abbe number that satisfy predetermined conditions.

An image pickup apparatus includes: a mount to which an interchangeable lens is mountable; an image sensor; an optical system having a refractive power and imaging an object point located on an image side of a most-object-side surface of the optical system onto the image sensor; and an optical filter arranged between the optical system and the image sensor, and a distance on an optical axis from a flange surface of the mount to the object point located on the image side of the most-object-side surface, a distance on the optical axis from the flange surface of the mount to the image pickup element, and a lateral magnification of the optical system when the interchangeable lens is mounted to the image pickup apparatus and the object point located on the image side of the most-object-side surface, is imaged onto the image pickup element, are appropriately set.

An image pickup apparatus includes: a mount to which an interchangeable lens is mountable; an image sensor; an optical system having a refractive power and imaging an object point located on an image side of a most-object-side surface of the optical system onto the image sensor; and an optical filter arranged between the optical system and the image sensor, and a distance on an optical axis from a flange surface of the mount to the object point located on the image side of the most-object-side surface, a distance on the optical axis from the flange surface of the mount to the image pickup element, and a lateral magnification of the optical system when the interchangeable lens is mounted to the image pickup apparatus and the object point located on the image side of the most-object-side surface, is imaged onto the image pickup element, are appropriately set.