Abstract: A zoom lens includes in order from an object side to an image side: a first lens unit having a positive refractive power not moving for zooming; at least three lens units moving during zooming; and a final lens unit having a positive refractive power, wherein an interval between adjacent lens units changes during zooming, a refractive index and an Abbe number of positive lenses arranged closest to the object side among positive lenses included in the first lens unit, a focal length of the first lens unit, a focal length of the zoom lens at a wide angle end, a focal length of the zoom lens at a telephoto end, and a back focus of the zoom lens at the wide angle end are appropriately set.

Abstract: A zoom lens includes, in order from object side, a positive first lens unit not moving for zooming, three or more intermediate lens units moving for zooming and a positive rear lens unit, in which each interval between adjacent lens units changes during zooming, an aperture stop is arranged in the rear lens unit, in a lens unit adjacent to the rear lens unit, or between the lens unit adjacent to the rear lens unit and the rear lens unit, the first lens unit includes, in order from the object side, negative subunit not moving for focusing, positive subunit moving for focusing, and positive subunit, a focal length of the first lens unit, a length on optical axis from most image-side surface to a rear principal point of the first lens unit, focal lengths of the zoom lens at wide angle end and at telephoto end are appropriately set.

Abstract: A zoom lens includes in order from an object side, a positive first unit, one or two second units including a negative lens unit closest to the image side, and monotonously moved to the image side for zooming to a telephoto end, one or two third units including a negative lens unit closest to the object side, and moved for zooming, and a positive fourth unit disposed closest to the image side, in which the first unit includes, in order from the object side, a negative subunit, a positive subunit moved for focusing, and a positive subunit, and a focal length of the first unit, a composite focal length at the telephoto end of the second unit, a maximum moving amount for zooming of the lens unit included in the second unit, and a maximum Abbe number of the negative lens included in the second unit are properly set.

Abstract: A zoom lens includes, from an object side a first lens unit (a positive refractive power) configured not to move for zooming, two or more intermediate lens units configured to move in zooming, and a rear lens unit (a positive refractive power), wherein an interval between each pair of adjacent lens units changes in zooming, the first lens unit includes, from the object side, a first lens subunit (a negative refractive power) configured not to move for focusing, a second lens subunit (a positive refractive power) configured to move for focusing, and a third lens subunit (a positive refractive power), the zoom lens satisfies specific inequalities concerning a focal length of the first lens unit, a length on an optical axis from a last surface to a rear principal point of the first lens unit, and a focal length of the zoom lens at a telephoto end.

Abstract: A zoom lens includes, in order from an object side, a positive first lens unit configured not to move for zooming, two or more intermediate lens units configured to move for zooming, and a positive rear lens unit. A distance between each pair of adjacent lens units changes for zooming. The first lens unit includes, in order from the object side, a negative first sub lens unit configured not to move for focusing, a positive second sub lens unit configured to move for focusing, and a positive third sub lens unit. Specific conditional expressions are satisfied with respect to a focal length and a thickness of the first lens unit, focal lengths of the zoom lens at a wide angle end and a telephoto end, a backfocus, and a focal length of the first sub lens unit.

Abstract: A zoom lens includes, 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 negative refractive power; and a third lens unit having a positive refractive power. The first lens unit does not move and the second lens unit and the third lens unit move in mutually different loci during zooming. Conditional expressions are satisfied as follows: 0.05<|f2/m2|<0.59, and 0.20<|f3/m3|<1.95, where f2 is a focal length of the second lens unit, f3 is a focal length of the third lens unit, m2 is a moving amount of the second lens unit during zooming from a wide-angle end to a telephoto end, and m3 is a moving amount of the third lens unit during zooming from the wide-angle end to the telephoto end.

Abstract: One or more eyepiece lenses, one or more observation apparatuses and one or more imaging apparatuses are discussed herein. In at least one embodiment, an eyepiece lens comprises, in order from an object side to an observation side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a negative refractive power, and a fifth lens having a positive refractive power, wherein a focal length of the fifth lens is shorter than a focal length of the third lens, and the focal length of the third lens is shorter than a focal length of the first lens.

Abstract: A zoom lens includes in order from an object side, a positive first unit, one or two second units including a negative lens unit closest to the image side, and monotonously moved to the image side for zooming to a telephoto end, one or two third units including a negative lens unit closest to the object side, and moved for zooming, and a positive fourth unit disposed closest to the image side, in which the first unit includes, in order from the object side, a negative subunit, a positive subunit moved for focusing, and a positive subunit, and a focal length of the first unit, a composite focal length at the telephoto end of the second unit, a maximum moving amount for zooming of the lens unit included in the second unit, and a maximum Abbe number of the negative lens included in the second unit are properly set.

Abstract: Provided is a zoom lens comprising, 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 negative refractive power, and a rear unit including at least one lens unit, in which the second lens unit is configured to move during zooming, an interval between each pair of adjacent lens units is changed during zooming, the rear unit has a positive refractive power over an entire zoom range, and the first lens unit includes a diffraction surface formed at a cemented surface of two optical elements cemented to each other. A focal length of the first lens unit, an amount of movement of the second lens unit during zooming from a wide angle end to a telephoto end and a back focus at the wide angle end are appropriately set.

Abstract: Provided is a small zoom lens having a high zoom ratio and easily designed to achieve favorable optical properties in an entire zooming range. A zoom lens includes, in order from object side to image side, a positive first unit, a negative second unit, an aperture stop, and a rear group including multiple units. Intervals between the adjacent units are changed during zooming. In the rear group, a positive lens unit is arranged on the most image side, and a negative lens unit is on the object side of the positive lens unit. The aperture stop not moving for zooming, but the second unit and the negative lens unit moving during zooming. Focal lengths of the second unit and the positive and negative lens units, and movement amounts of the second and negative lens units, respectively, during zooming from wide angle end to telephoto end are appropriately set.

Abstract: Provided is a zoom lens comprising, 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 negative refractive power, and a rear unit including at least one lens unit, in which the second lens unit is configured to move during zooming, an interval between each pair of adjacent lens units is changed during zooming, the rear unit has a positive refractive power over an entire zoom range, and the first lens unit includes a diffraction surface formed at a cemented surface of two optical elements cemented to each other. A focal length of the first lens unit, an amount of movement of the second lens unit during zooming from a wide angle end to a telephoto end and a back focus at the wide angle end are appropriately set.

Abstract: A zoom lens includes, 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 negative refractive power; and a third lens unit having a positive refractive power. The first lens unit does not move and the second lens unit and the third lens unit move in mutually different loci during zooming. Conditional expressions are satisfied as follows: 0.05<|f2/m2|<0.59, and 0.20<|f3/m3|<1.95, where f2 is a focal length of the second lens unit, f3 is a focal length of the third lens unit, m2 is a moving amount of the second lens unit during zooming from a wide-angle end to a telephoto end, and m3 is a moving amount of the third lens unit during zooming from the wide-angle end to the telephoto end.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, and a fourth lens unit having positive refractive power. During zooming from a wide-angle end to a telephoto end, the first lens unit does not move and at least the second lens unit and the fourth lens unit move. A distance between adjacent lens units varies during zooming. In the zoom lens, a lens configuration of the first lens unit, a lens configuration of the second lens unit, a focal length of each lens unit, a focal length of the zoom lens at a wide-angle end, and a lateral magnification of the second lens unit during focusing on an infinite-distance object at the telephoto end are appropriately set based on predetermined conditions.

Abstract: Provided is a small zoom lens having a high zoom ratio and easily designed to achieve favorable optical properties in an entire zooming range. A zoom lens includes, in order from object side to image side, a positive first unit, a negative second unit, an aperture stop, and a rear group including multiple units. Intervals between the adjacent units are changed during zooming. In the rear group, a positive lens unit is arranged on the most image side, and a negative lens unit is on the object side of the positive lens unit. The aperture stop not moving for zooming, but the second unit and the negative lens unit moving during zooming. Focal lengths of the second unit and the positive and negative lens units, and movement amounts of the second and negative lens units, respectively, during zooming from wide angle end to telephoto end are appropriately set.

Abstract: A zoom lens includes: a first lens unit having a negative refractive power; and a rear group having a positive refractive power, in which, when a focal length of the zoom lens is a shortest focal length, a maximum image height is lower than a half of a diagonal length of an image pickup region, and when a focal length of the zoom lens at which the maximum image height becomes a half of the diagonal length of the image pickup region is defined as an intermediate focal length, a focal length of the zoom lens at a longest focal length, a half angle of field of the zoom lens at the longest focal length, and other such factors are appropriately set so that the maximum image height is increased continuously from the shortest focal length to the intermediate focal length.

Abstract: A zoom lens includes: a first lens unit having a negative refractive power; and a rear group having a positive refractive power, in which, when a focal length of the zoom lens is a shortest focal length, a maximum image height is lower than a half of a diagonal length of an image pickup region, and when a focal length of the zoom lens at which the maximum image height becomes a half of the diagonal length of the image pickup region is defined as an intermediate focal length, a focal length of the zoom lens at a longest focal length, a half angle of field of the zoom lens at the longest focal length, and other such factors are appropriately set so that the maximum image height is increased continuously from the shortest focal length to the intermediate focal length.

Abstract: A 3D-image pickup optical system includes: a pair of optical systems each of which includes a magnification-varying lens unit, an aperture stop, a first lens unit and a first reflective member in a sequential order from an object side, the optical systems having optical axes offset from each other; a second lens unit that receives object light fluxes from the pair of optical systems; a second reflective member that guides the object light fluxes from the pair of optical systems to the second lens unit; and a switching unit that is disposed in an object side of the second reflective member, and alternately guides the pair of the object light fluxes respectively from the pair of optical systems to the second reflective member.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, a third lens unit having positive refractive power, and a fourth lens unit having positive refractive power. During zooming from a wide-angle end to a telephoto end, the first lens unit does not move and at least the second lens unit and the fourth lens unit move. A distance between adjacent lens units varies during zooming. In the zoom lens, a lens configuration of the first lens unit, a lens configuration of the second lens unit, a focal length of each lens unit, a focal length of the zoom lens at a wide-angle end, and a lateral magnification of the second lens unit during focusing on an infinite-distance object at the telephoto end are appropriately set based on predetermined conditions.

Abstract: A zoom lens includes, in order from an object side: a positive first lens unit that does not move for zooming and comprises a negative first sub-lens unit, a positive second sub-lens unit that moves during adjustment of a focal point, and a positive third sub-lens unit composed of at least one negative lens, and at least two positive lenses; a lens group including at least two lens units that move during zooming; an aperture stop; and a positive last lens unit that does not move for zooming. Focal lengths of the first lens unit, the first sub-lens unit, and the zoom lens at a wide angle end, imaging magnification of the last lens unit, average values of an Abbe constant for d-line of the at least one negative lens and of the at least two positive lenses are appropriately set.

Abstract: A lens apparatus includes, in order from an object side: a first lens unit; an aperture stop; and a positive second lens unit. The first lens unit includes, in order from the object side, a first negative lens, a second negative lens having at least one aspheric surface, and a positive lens. The second lens unit includes at least one negative lens and at least two positive lenses. The first and second negative lenses of the first lens unit are meniscus lenses having a surface convex toward the object side. The focal length of the optical system, the focal lengths of the first and second lens units, the mean values of Abbe constants of the positive lens and the negative lenses of the first lens unit, and the mean values of Abbe constants of the positive lenses and the negative lenses of the second lens unit are appropriately configured.