Abstract: This application discloses a lens system comprising in order from an object side to an image side: an aperture stop; a first lens element, having a positive optical power; and a second lens element, having a negative optical power. By setting the shapes of the respective lens elements and the materials making up the respective lens elements so as to meet predetermined conditions in such a lens system, a lens system of a compact size which provides good optical performance is realized while securing telecentric characteristics.

Abstract: A zoom lens, including, in order from an object side to an image side (a) a first lens unit of negative optical power, (b) a second lens unit of positive optical power, and (c) a third lens unit of positive optical power, wherein a separation between the first lens unit and the second lens unit and a separation between the second lens unit and the third lens unit are varied to effect variation of magnification, and wherein, during the variation of magnification from a wide-angle end to a telephoto end with an infinitely distant object focused on, the third lens unit moves monotonically toward the image side or moves with a locus convex toward the image side.

Abstract: A zoom lens, including, in order from an object side to an image side (a) a first lens unit of negative optical power, (b) a second lens unit of positive optical power, and (c) a third lens unit of positive optical power, wherein a separation between the first lens unit and the second lens unit and a separation between the second lens unit and the third lens unit are varied to effect variation of magnification, and wherein, during the variation of magnification from a wide-angle end to a telephoto end with an infinitely distant object focused on, the third lens unit moves monotonically toward the image side or moves with a locus convex toward the image side.

Abstract: In a zoom lens comprising 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 in order from the object side to the image side, and performing zooming by changing the intervals between the lens units, the third lens unit is constituted by a first lens sub-unit and a second lens sub-unit in order from the object side to the image side, and an image formed by the zoom lens system is displaced by the movement of the second lens sub-unit so as to have a component in the direction perpendicular to the optical axis. Moreover, the first lens sub-unit and the second lens sub-unit constituting the third lens unit are set to positive refractive power, the first lens sub-unit is constituted by a positive lens and a negative lens and the second lens sub-unit is constituted by one lens component.

Abstract: A zoom lens, including, in order from an object side to an image side (a) a first lens unit of negative optical power, the first lens unit consisting of, in order from the object side to the image side, a negative lens and a positive lens, (b) a second lens unit of positive optical power, and (c) a third lens unit of positive optical power, wherein a separation between the first lens unit and the second lens unit and a separation between the second lens unit and the third lens unit are varied to effect variation of magnification, wherein, during the variation of magnification from a wide-angle end to a telephoto end with an infinitely distant object focused on, the third lens unit moves monotonically toward the image side or moves with a locus convex toward the image side.

Abstract: A zoom lens system capable of correcting a secondary spectrum is disclosed. The zoom lens system includes a first lens unit with a positive optical power, a second lens unit with a negative optical power, an aperture stop, and a rear lens component including at least one lens unit in an order from an object side to an image side. In the zoom lens system, during zooming from a wide angle end to a telephoto end, an interval between the first lens unit and the second lens unit increases, and an interval between the second lens unit and the aperture stop decreases. Then, a material satisfying the following conditions: ?d1n<35 ?gF1n<?0.0027?d1n+0.680 is used for the negative lens in the first lens unit. Herein, ?d1n represents an Abbe number, and ?gF1n represents a partial dispersion ratio.

Abstract: A zoom lens system with a new structure is disclosed which realizes high optical performance by appropriately setting the structure of each lens unit and using a material with anomalous dispersion in an appropriate lens unit. Specifically, according to several aspect herein disclosed, the zoom lens system includes, in order from an object side to an image side, lens units having a positive, a negative, and a positive optical powers in which the structure of each lens unit is specified or a third lens unit employs a lens element made of a material with anomalous dispersion.

Abstract: A zoom lens which suppresses variations of an exit pupil and is telecentric on the image side in the whole range of zooming comprises, from the object side toward the image side: a first negative in optical power, an aperture stop, a second lens unit positive in optical power and a third lens unit positive in optical power. In zooming from the wide angle end to telephoto end, the distance between the first lens unit and the aperture stop narrows, the between the aperture stop and the second lens unit narrows, and the between the second lens unit and the third lens unit widens; and the condition: 0<(Dw?Dt)/fw<1 is satisfied, where is the distance between aperture stop and the second lens unit at the wide angle end is Dw, at the telephoto end is Dt and the focal length at the wide angle end fw.

Abstract: In a zoom lens comprising 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 in order from the object side to the image side, and performing zooming by changing the intervals between the lens units, the third lens unit is constituted by a first lens sub-unit and a second lens sub-unit in order from the object side to the image side, and an image formed by the zoom lens system is displaced by the movement of the second lens sub-unit so as to have a component in the direction perpendicular to the optical axis. Moreover, the first lens sub-unit and the second lens sub-unit constituting the third lens unit are set to positive refractive power, the first lens sub-unit is constituted by a positive lens and a negative lens and the second lens sub-unit is constituted by one lens component.

Abstract: A zoom lens is constructed with, in order from an object side to an image side, a first lens unit of negative optical power, the first lens unit including a negative meniscus lens having a concave surface facing the image side and a positive meniscus lens having a convex surface facing the object side, a second lens unit of positive optical power, the second lens unit including a cemented lens of positive optical power as a whole disposed on the most image side of the second lens unit, and a lens having a concave surface facing the image side and adjoining a surface on the object side of the cemented lens, and a third lens unit of positive optical power, wherein a separation between the first lens unit and the second lens unit and a separation between the second lens unit and the third lens unit are varied to effect variation of magnification.

Abstract: A zoom lens is constructed with, in order from an object side to an image side, a first lens unit of negative optical power, the first lens unit including a negative meniscus lens having a concave surface facing the image side and a positive meniscus lens having a convex surface facing the object side, a second lens unit of positive optical power, the second lens unit including a cemented lens of positive optical power as a whole disposed on the most image side of the second lens unit, and a lens having a concave surface facing the image side and adjoining a surface on the object side of the cemented lens, and a third lens unit of positive optical power, wherein a separation between the first lens unit and the second lens unit and a separation between the second lens unit and the third lens unit are varied to effect variation of magnification.

Abstract: A zoom lens is constructed with, in order from an object side to an image side, a first lens unit of negative optical power, the first lens unit including a negative meniscus lens having a concave surface facing the image side and a positive meniscus lens having a convex surface facing the object side, a second lens unit of positive optical power, the second lens unit including a cemented lens of positive optical power as a whole disposed on the most image side of the second lens unit, and a lens having a concave surface facing the image side and adjoining a surface on the object side of the cemented lens, and a third lens unit of positive optical power, wherein a separation between the first lens unit and the second lens unit and a separation between the second lens unit and the third lens unit are varied to effect variation of magnification.

Abstract: In order to provide a zoom lens which has excellent optical performance with a compact configuration using a small number of constituent lenses, a zoom lens according to the present invention comprises a first lens unit having a negative optical power, a second lens unit having a positive optical power, and a third lens unit having a positive optical power, which are sequentially arranged from the object side, wherein the gap between the first and second lens units is decreased, the space between the second and third lens units is increased in zooming from the side angle end to the telephoto end, the third lens unit has a cemented lens formed by cementing a positive lens element to a negative lens element, and is moved along the optical axis for zooming, and letting NLi be the number of lensess constituting the ith lens unit, a condition, NL3<NL2?NL1 is satisfied.

Abstract: A zoom lens is constructed with, in order from an object side to an image side, a first lens unit of negative optical power, the first lens unit including a negative meniscus lens having a concave surface facing the image side and a positive meniscus lens having a convex surface facing the object side, a second lens unit of positive optical power, the second lens unit including a cemented lens of positive optical power as a whole disposed on the most image side of the second lens unit, and a lens having a concave surface facing the image side and adjoining a surface on the object side of the cemented lens, and a third lens unit of positive optical power, wherein a separation between the first lens unit and the second lens unit and a separation between the second lens unit and the third lens unit are varied to effect variation of magnification.

Abstract: This invention provides a zoom lens system with, in succession from the front to rear, a first lens unit of negative optical power, a second lens unit of positive optical power and a third lens unit of positive optical power. When zooming from a short focal length end to a long focal length end, the second lens unit moves forward, while the third lens unit moves along a locus that is located rearmostly at other zoom position than the short focal length end and that is convex toward the image side or a part of it. The first lens unit does not move. Further, the first lens unit has a negative lens with a concave rear surface, and a positive lens with a convex front surface. The second lens unit has a negative lens with a concave rear surface, and a positive lens disposed rearwardly of the negative lens.

Abstract: This application discloses a lens system comprising in order from an object side to an image side: an aperture stop; a first lens element, having a positive optical power; and a second lens element, having a negative optical power. By setting the shapes of the respective lens elements and the materials making up the respective lens elements so as to meet predetermined conditions in such a lens system, a lens system of a compact size which provides good optical performance is realized while securing telecentric characteristics.

Abstract: A reflecting-type optical system according to the invention includes an optical element composed of a transparent body having an entrance surface, an exit surface and at least three curved reflecting surfaces of internal reflection. A light beam coming from an object and entering at the entrance surface is reflected from at least one of the reflecting surfaces to form a primary image within the optical element and is, then, made to exit from the exit surface through the remaining reflecting surfaces to form an object image on a predetermined plane. In the optical system, 70% or more of the length of a reference axis in the optical element lies in one plane.

Abstract: A zoom lens system with a new structure is disclosed which realizes high optical performance by appropriately setting the structure of each lens unit and using a material with anomalous dispersion in an appropriate lens unit. Specifically, according to several aspect herein disclosed, the zoom lens system includes, in order from an object side to an image side, lens units having a positive, a negative, and a positive optical powers in which the structure of each lens unit is specified or a third lens unit employs a lens element made of a material with anomalous dispersion.

Abstract: The disclosed zoom lens includes a first lens unit having a negative optical power, a second lens unit having a positive optical power, and a third lens unit having a positive optical power in order from an object side to an image side. The zoom lens has a shorter interval between the first lens unit and the second lens unit and a longer interval between the second lens unit and the third lens unit on a telephoto end than an interval between the first lens unit and the second lens unit and an interval between the second lens unit and the third lens unit on a wide angle end, respectively.

Abstract: A zoom optical system comprises a plurality of optical elements. The plurality of optical elements include a first optical element having two refracting surfaces and a plurality of reflecting surfaces formed in a transparent body, being arranged such that a light beam enters an inside of the transparent body from one of the two refracting surfaces and, after being successively reflected from the plurality of reflecting surfaces, exits from the other of the two refracting surfaces, and/or a second optical element having a plurality of surface mirrors integrally formed and decentered relative to one another, being arranged such that an incident light beam exits therefrom after being successively reflected from reflecting surfaces of the plurality of surface mirrors, and a third optical element composed of a plurality of coaxial refracting surfaces.